Nuclear Energy

  • Nuclear energy comes from the splitting of uranium atoms in a reactor to produce heat to convert water into steam which is used by a turbine generator to generate electricity.
  • It comes from the conversion of mass energy in the nuclei of atoms into heat energy of the material containing the nuclei which undergoing a nuclear reaction.

Nuclear Energy || Definition, Facts, Uses & Advantages

  • The magnitude of this energy conversion is about 108 times which is greater than that for chemical reactions.
  • It is the world’s largest sources of emission free energy.
  • Enrico Fermi who invented nuclear energy.

Definition of Nuclear Energy

  • The energy released during a nuclear reaction due to the nucleus of an atom is called nuclear energy.
  • It is also known as atomic energy because it can be considered to be coming from the atoms.

Types of Nuclear Reaction

  • It can be obtained by two types of nuclear reactions:-

1. Nuclear Fission

2. Nuclear Fusion

1. Nuclear Fission

  • The word  ‘fission’ means to ‘ split up ‘ into two or more parts.
  • The process in which the heavy nucleus of a radioactive atom splits up into smaller nuclei when bombarded with low energy neutrons, is called nuclear fission.
  • It produced tremendous amount of energy.
  • Nuclear fission is carried out by bombarding the heavy nuclei with low energy neutrons which are additionally called slow moving neutrons.

Nuclear Energy || Definition, Facts, Uses & Advantages

  • For e.g. uranium-235 atoms are bombarded with slow moving neutrons, the heavy uranium nucleus breaks up to deliver two medium weight molecules, Barium-139 and Krypton 94, with the discharge of 3 neutrons. This fission reaction can be represented in the form of a nuclear equation as:-

Nuclear Energy || Definition, Facts, Uses & Advantages

  • In the fissioning of uranium, some mass of uranium disappears and a tremendous amount of energy is produced.
  • The fission of 1 atom of uranium-235 produces 10 million times more energy than the energy produced by the burning of 1 atom of carbon from coal.
  • This happens due to the conversion of mass into energy.

Control Nuclear Fission Reaction

  • Reaction of nuclear fission is controlled by rods made of boron.
  • Boron has a property that it can absorb neutrons.
  • So, when a nuclear fission reaction is carried out in the presence of boron rods.
  • The excess neutrons created during successive fissions of uranium- 235 atoms are absorbed by boron rods and hence not available to cause further fission.
  • Because of this a controlled fission reaction of uranium- 235 takes place liberating heat energy at a slow, steady and manageable rate which can be used for generating electricity at a nuclear power plant.

Difference Between Controlled & Uncontrolled Nuclear Reaction

S. NO. Controlled Nuclear Reaction Uncontrolled Nuclear Reaction
1. In a controlled fission reaction for every one neutron absorbed, only one neutron is available for further fission. In an uncontrolled nuclear chain reaction, three neutrons are produced for each neutron absorbed. Each released neutron further produces three more neutrons and thus the chain reaction continues until explosion takes place.
2. The controlled fission reaction proceeds at a steady rate. The energy released can be utilized for useful purposes.  The uncontrolled fission reaction becomes explosive and the released energy cannot be used for useful purposes.

Einstein’s Mass Energy Relation

  • It states that mass and energy are equivalent, and are related by the equation:-

E = mc²

  where,

    E = Amount of energy

    m = Mass Destroyed

     c = Speed of light in vacuum

  • Since the speed of light is very, very large, so an extremely large amount of energy is produced even if small mass gets destroyed.
  • The destruction of mass happens in nuclear reactions with the liberation of tremendous amount of energy.
  • The mass – energy equation, if we put the mass in kilograms ( kg ), and the speed of light in metres per second ( m/s ), then the energy will come in joules ( J ).
  • For e.g. if a mass of 1 kg of any matter could be destroyed in a nuclear reaction, then the amount of energy produced would be given by Einstein’s equation as:-

E = mc²

E = 1 × ( 3 × 108

E = 9 × 1016 J

  Thus, 1 kg mass produces a huge amount of energy of 9 × 1016 J.

2. Nuclear Fusion

  • The process of nuclear fusion was discovered in 1930s.
  • The word ‘ fusion ‘ means ‘ to join ‘ & ‘ to combine ‘.
  • The process in which two nuclei of lighter elements combine to form a heavy nucleus, is called nuclear fusion.

Nuclear Energy || Definition, Facts, Uses & Advantages

 

  • The energy produced in a fusion reaction is much higher than that produced in a nuclear fission reaction.
  • It takes place only at a very high temperature, about 4 – 15 million degrees. That is why nuclear fusion is also called thermonuclear reaction.

Typical Fusion reactions are:-

  • Fusion reaction between two deuteron nuclei forming helium – 3 and a neutron.

Nuclear Energy || Definition, Facts, Uses & Advantages

or

  • Fusion reaction between two deuteron nuclei forming Triton and a proton.

Nuclear Energy || Definition, Facts, Uses & Advantages

or

where,

t= Triton, a nucleus containing one proton and two neutrons

d= deuteron, a nucleus containing one proton and one neutron

  • Fusion reaction between two high speed colliding protons, leading to the formation of a neutron, a positron and a neutrino is also a nuclear fusion reaction. A large amount of energy is also released.

Nuclear Energy || Definition, Facts, Uses & Advantages

  • In this reaction, one of the protons is converted into a neutron and a positron ( e+ ).

Differences Between Nuclear Fission & Nuclear fusion

S.NO. Nuclear Fission Nuclear Fusion
1. In nuclear fission, a heavy nucleus breaks down into two or more lighter ones. In nuclear fusion, two lighter nuclei combine to form a heavier nucleus.
2. Nuclear fission can take place at all temperatures. Nuclear fusion takes place only at a very high temperature.
3. It needs a certain minimum amount of fuel. There is no minimum limit to the amount of fuel.
4. Products of nuclear fission are generally radioactive. Products of nuclear fusion are generally not radioactive.

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Nuclear Energy Facts

  • It produced 809 billion kilowatt hours of electricity in 2019.
  • It provides 55% of America’s clean energy.
  • This is most reliable energy source in America.
  • It helps to power 29 states of U.S.
  • This fuel is extremely dense.

Nuclear Energy Pros And Cons

S. NO. Pros Cons
1. It produces immense power from tiny amounts of fuel. Nuclear waste gives off dangerous radiation power much over 1,000 years.
2. Nuclear fuels will last for longer than fossil fuels such as coal, oil, and natural gas burned in other power plants. Safety staring the waste is a huge problem.
3. Nuclear power plants produce clean energy that adds little to air and water pollution. All of the nuclear waste made in the United states over the last 40 years could cover a football field, 15 feet deep.
4. Burning of fossil-fuel burning plants produce much pollution including acid rain. Nuclear energy has several huge drawbacks. High level waste that produces strong radioactivity remains dangerous for hundreds-even thousands of years.
5.  Nuclear energy workers wear special suits and respirators that become contaminated with low levels of radiation. No nuclear waste storage area is totally safe for workers. Also the waste sites must be safely guarded to prevent intruders.
6. For every kilogram of nuclear energy produced, it is the same as using 1,000 pounds of coal. Finally, as current storage areas fill up, we should manufacture new, safe sites for future nuclear wastes.

Nuclear Energy Hazards

  • The damaging and harmful effects associated with nuclear reactions are called nuclear hazards.
  • Most substances engaged with the generation of nuclear energy are radioactive.
  • These substances emit harmful radiation. These are called nuclear radiations.
  • Nuclear radiations have very harmful effects on human bodies and vegetation.
  • The harmful effects of the nuclear radiation on human body are of two types:-

1. Somatic effects

2. Genetic effects

1. Somatic effects

  • The somatic effects involve damage to the body cells leading to the diseases such as cancer.

2. Genetic effects

  • The genetic effects involve damage to the genes of the affected person.
  • These effects are very serious and may be passed on to the next generation.

Safety Measures of Nuclear Energy 

  • The nuclear reactor should be located at a place far away from high population areas.
  • The nuclear reactor should be provided with a thick coating of radiation absorbing material and enclosed in a thick concrete shield to prevent any radiation leakage.
  • The building and the entire structure for the nuclear reactor should be earthquake-proof.
  • We should start using non- conventional sources of energy.

Uses of Nuclear Energy

  • It is used in the field of electric power generation.
  • They are mostly used in the field of medicine.
  • It is also used in the field of food & agriculture.
  • It is used in industrial applications as well as consumer products.
  • They are mostly used in the field of scientific research and space.

Advantages of Nuclear Energy

  • It delivers a large amount of useful energy from a very small amount of a nuclear fuel.
  • When the atomic fuel is stacked into the reactor, the atomic force plant can continue delivering power for a few years at a stretch. There is no requirement for placing in atomic fuel over and over.
  • It doesn’t produce gases like carbon dioxide which contributes to greenhouse effect or sulphur dioxide which causes acid rain.

Disadvantages of Nuclear Energy

  • The waste products of nuclear reactions are radioactive which keep on emitting harmful nuclear radiations for thousands of years. So, it is very difficult to store or dispose off nuclear wastes safely.
  • Improper nuclear waste storage or disposal can contaminate the earth.
  • There is the risk of accidents in nuclear reactors. Such accidents lead to the leakage of radioactive materials which can cause serious damage to the plants, animals and the nature.
  • The high cost of installation of nuclear power plants and the limited availability of uranium fuel make the enormous scope utilization of nuclear energy prohibitive.

Let’s Know More

1. What is a nuclear reaction ?

Ans:- The reaction in which composition of the reacting nuclei changes to form nuclei of the lighter elements with a simultaneous release of a large amount of energy is called a nuclear reaction.

2. Differences between chemical and nuclear reaction.

Ans:-

S.NO. Chemical Reaction Nuclear Reaction
1. In chemical reactions, new compounds are formed but the basic elements remain the same. In nuclear reaction, new elements are formed due to the splitting or fusion of the nuclei.
2. In chemical reaction, only the electronic configurations change. In nuclear reactions, composition of the nuclei changes.
3. The energy is released of the order of 100-200 kJ. It releases very large amount of energy i.e approx. 1 million joules.
4. Chemical reaction can be reversed. Nuclear reactions are irreversible.
5. The rate of a chemical reaction is affected by change in temperature and pressure. There are no effect on the rate of a nuclear reaction when pressure / temperature are changed.

3. What are the components of a nuclear energy power plant?

Ans:- A nuclear energy power plant consists of the following components:-

Nuclear Energy || Definition, Facts, Uses & Advantages

A. Nuclear reactor – Here, a controlled nuclear fission of a fissionable fuel such 235 92U is carried out.

B. Heat exchanger – The reactor is connected to a heat exchanger. Here, the heat produced in the reactor is transferred to water by circulating a coolant is pumped back to the reactor.

C. Steam turbine – The steam generated in the heat exchanger is used to run the steam turbine. The spent steam is sent back as hot water to the heat exchanger.

D. Electric generator ( Dynamo ) – The shaft of the steam turbine is connected to an electric generator. Electricity so produced is sent for transmission.

4. Why can’t nuclear fusion be carried out in a nuclear reactor ?

Ans:- Nuclear fusion reaction takes place at extremely high temperature. Such a higher temperature can’t be obtained for a reasonable length of time in a laboratory. Moreover, technically, there is no suitable material available which would be able to withstand such a high temperature. As a result, it is not possible to have a nuclear reactor based on the principle of nuclear fusion.

5. What are nuclear radiations?

Ans:- The rays and the particles emitted due to natural radioactivity and during nuclear fission are collectively called nuclear radiations.

  •   Most common nuclear radiations are

A. Alpha ( α ) particles

B. Beta ( β ) particles

C. Gamma ( γ ) particles

D. X – rays

E. High energy neutrons

6. How is nuclear energy waste generated ?

Ans:- Nuclear energy waste is generated in the following manner:-

A. From nuclear reactors

B. During mining of the radioactive materials

C. At nuclear fuel processing complexes

D. At laboratories and hospitals which use radioactive isotopes for research or medical purposes.

7. What is Hydrogen Bomb?

Ans:- Thermonuclear reactions are used for producing a weapon of mass destruction called Hydrogen Bomb.

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Soil

  • Soil is the layer of broken rock particles and decaying organic matter on the surface of earth, which is essential for the growth of living organisms.

Rock particles + Humus → Soil

  • It is the most important renewable natural resource.
  • It is a life – support medium, providing sustenance to plants and animals.
  • All living beings depend directly or indirectly on soil for food.

Soil || Definition, Types, Importance & Advantages

  • The best soil is usually found in river valleys where silt gets renewed automatically by annual flooding.
  • This makes the soil of the river valleys extremely fertile.
  • The Nile Valley in Egypt, the Mississippi Valleys in the USA and the Yangtze – Kiang Valley in China are some examples of fertile river valleys.

Definition of Soil

  • The uppermost layer of the earth’s crust is called soil.
  • It is soft and porous.
  • Its thickness ranges from a few millimetres to 3-4 metres.

Soil Formation

  • The formation of soil takes place by a process known as weathering.
  • Weathering is the process in which big rocks breakdown into smaller pieces by weathering agents like water, storm, etc.
  • Weathering is a very slow and gradual process during which the parent rock material breaks down into fine particles.
  • During the formation of soil particles, the smaller particles undergo decomposition by a number of processes such as reduction, oxidation, hydrolysis and carbonation.
  • The formation of soil is influenced by a number of factors like climate, parent rock material, vegetation and time.

Process of Weathering

  • Factors ( agents ) responsible for weathering of rocks are :-

1. Temperature Changes

2. Living Organisms

3. Frost

4. Water

5. Wind

1. Temperature Changes

  • Rocks heat up and expand during day, owing to sunlight but they contract when the temperature falls during night.
  • This successive expansion and contraction weakens rocks causing them to weather.

2. Living Organisms

  • Weathering by living organisms is called biological weathering.
  • Certain life forms like the lichens can grow on the surface of rocks.
  • The lichens produce acids which corrode the rocky surface, and produce fine particles.
  • Then, in these fine particles other organisms like microbes, algae, insects and worms produce some chemicals that add up to the process of weathering.

3. Frost

  • Rain water may become trapped in small crevices of the parent rock.
  • In winter, this water freezes to ice.

Soil || Definition, Types, Importance & Advantages

  • The ice expands producing a lateral pressure, causing the crevices in the rocks to open up and causing weathering.

4. Water

Soil || Definition, Types, Importance & Advantages

 

  • Continual movement of rain and river water, in liquid form, causes breaking down of rock particles into finer particles through their abrasive effect.

5. Wind

Soil || Definition, Types, Importance & Advantages

  • The broken pieces of rocks are carried away by winds.
  • Winds make these pieces of rocks collide with the ground and with each other.
  • This result in the conversion of small pieces of rocks into tiny particles.

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Soil Profile

  • The different layers of soil arranged in a vertical section of soil is called soil profile
  • In the soil profile, we dig a trench vertically down at a particular place, along the sides of trench than we can see several layers, or horizons.
  • They are named as follows:-

Soil || Definition, Types, Importance & Advantages

1. Topsoil ( A – horizon )

2. Subsoil ( B – horizon )

3. Parent rock ( C – horizon )

1. Topsoil ( A – horizon )

  • It is the uppermost layer of soil.
  • It is also known as topsoil.

Features of A – horizon

  • It is the darkest in colour.
  • It is rich in humus. Humus is formed by the death and decay of plants and animals. Humus means more organic matter.
  • This is very fertile due to humus.
  • Its layer is soft, porous and holds enough water.
  • The roots of plants are present. In case of tall trees, the roots may go further down to the second horizon.
  • Living organisms like earthworms, insects, bacteria and fungi are present in this layer.

2. Subsoil ( B – horizon )

  • It is situated below the topsoil.

Features of B – horizon

  • It is lighter in colour than the upper layer.
  • It is harder and more compact than the A – horizon.
  • This layer is rich in soluble minerals and iron oxides.
  • Remains of plants and animals are not found in this layer.
  • Roots of tall plants generally reach this level.
  • Very little organic matter is found.

3. Parent rock ( C – horizon )

  • It is the lowest of all the three layers and is found below B- horizon.
  • It is composed of small pieces of rocks with crevices.
  • This layer also collects rainwater.
  • Beneath the C – horizon is the bed rock itself.
  • The bed rock cannot be easily dug up.

Composition of Soil

  • Soil is composed of various types of constituents. It consists 45 % minerals, 25 % water, 25 % air and 5 % organic matter with an average soil sample.
  • The main constituents of soil are:-

1. Organic material

2. Inorganic material

1. Organic material

  • The organic material is decaying living matter like plants or animals.
  • They consists following components:-

A. Humus

B. Living organisms

A. Humus

  • Humus is formed by the decomposition of dead plants and animals.
  • Microorganisms present in the soil help in the decomposition of plant and animal remains.
  • All this decomposed matter mixes with the soil.

Soil || Definition, Types, Importance & Advantages

  • This matter is very rich in nutrients required by plants.
  • That’s why, the presence of humus is largely responsible for the fertility of soil.
  • Humus is also responsible for a good texture of soil.
  • Organisms living in the soil feed on humus.

B. Living organisms

  • Microorganisms like bacteria and fungi live in the soil.
  • They help in decaying of organic matter and thus contribute to the formation of humus.
  • Some bacteria also play an important role in nitrogen fixation.

2. Inorganic material 

  • The inorganic materials are the rocks which have been broken down into smaller pieces.
  • It consists following components:-

A. Minerals

B. Air and Water

A. Minerals

  • Minerals like calcium, phosphorous, potassium, magnesium, iron, etc are present in rocks from which the soil is formed.
  • In different rocks different kinds of minerals are found.

B. Air and Water

  • Soil contains air trapped within it.
  • This air helps roots and soil organisms to respire.
  • Rainwater and the water used in irrigation seeps through soil.
  • This water is absorbed by roots and transported through the steams to be used by plants for their vital functions.

Soil Colour

  • The different soil components impart a characteristic colour to the soil as a whole.
  • Soils exhibit a variety of colours, ranging from white, grey, yellow and red to black.
  • Dark coloured soils are richer in organic matter than the light- coloured soils.
  • Red coloured soils contain more of oxides of iron.
  • Laterite soils are also red coloured.
  • Thus, the colour of the soils give you an idea about the chemicals it contains.
  • The soil colour, however, also differs depending on the geographic location of the soil.
  • For instance, red and yellow colours of the soils increase from the cool regions to the equator.

Types of Soil

  • Soil of different places has different composition and different properties.
  • This difference is due to the difference in the particle size of the soils of different places.
  • Soil particles may be of following types according to their size:-

1. Clayey Soils

2. Sandy Soils

3. Loamy Soils

4. Silt Soils

5. Gravel Soils

1. Clayey Soils

  • The amount of clay particles is more in this type of soil.
  • As these are the smallest particles, they from a very compactly packed soil with little air spaces.
  • But its water – holding capacity is very high.

Soil || Definition, Types, Importance & Advantages

  • Humus is present in a small amount in this soils.
  • It is smooth to touch and heavy because of water held by it.
  • It is light grey in colour.
  • This is used by potters to make earthen pots, vessels and statues.

2. Sandy Soils

  • In it, large amount of sand particles are present.
  • There particles are big. So, they are not very tightly packed and have large air spaces between them.
  • Air can be held in this type of soils. But the same property makes it unable to hold much water.

Soil || Definition, Types, Importance & Advantages

  • So, its water retention capacity is very low as water drains away through it.
  • It is rough to touch.
  • It is light brown in colour.

3. Loamy Soils

  • It is a mixture of sand, silt and clay along with the adequate amount of humus.
  • It is the most suitable for growing plants.

Soil || Definition, Types, Importance & Advantages

  • The sand present in it provides air -holding capacity while clay provides water retention capacity.
  • It is neither too rough nor too smooth to touch.
  • It is dark brown in colour.

4. Silt Soils

Soil || Definition, Types, Importance & Advantages

  • It is very small and broken pieces of rock.
  • It is larger than clay, but smaller than sand.
  • They are in the form of powdery when dry.

5. Gravel Soils

Soil || Definition, Types, Importance & Advantages

  • It is rock that is of a specific particle size range.
  • It is any loose rock that is larger than 2 mm in its smallest dimension and no more than 64 mm.

Classification of Soils

  • On the basis of mode or place of soil formation, it is classified into three types:-

1. Residual Soils

2. Transported Soils

3. Mountainous Soils

1. Residual Soils

  • It is those in which the whole process of soil formation, i.e., weathering and development of its profile occur at the same place.
  • Red, black, laterite soil are examples of it.

2. Transported Soils

  • It is carried to some other place by gravity, flowing water or wind.
  • For e.g. alluvial and desert soil.

3. Mountainous Soils

  • They are usually found in depressions and valley basins or on slightly inclined mountain slopes.
  • On the basics of chemical nature, soils may be acidic, alkaline or neutral.
  • Most fertile agricultural fields are neutral in nature.
  • Extreme acidic or alkaline soils do not support plant growth.

Types of Soils in India

  • India has a variety of relief, climate and parent rock structures.
  • Due to these varied features, India has a rich variety of soils.
  • The Indian soil structure can be divided into the following categories;-

Soil || Definition, Types, Importance & Advantages

1. Alluvial Soil

2. Black Soil

3. Red Soil

4. Laterite Soil

5. Desert Soil

6. Mountain Soil

1. Alluvial Soil

  • This is formed in the river valleys and the deltas.
  • Deltas are also called coastal plains.

Soil || Definition, Types, Importance & Advantages

  • It consists of round and smooth particles and is stratified.
  • It is loamy and rich in organic matter.
  • This is the best types of soil for growing crops like wheat and rice.

2. Black Soil

Soil || Definition, Types, Importance & Advantages

 

  • It is mainly found in the north – western part of the Deccan Plateau.
  • It is compact and fine – grained in texture and remain moist for a long time.
  • This one rich in iron content and is an ideal for growing cotton and sugarcane.

3. Red Soil

  • It is found in abundance eastern and southern parts of peninsular India.
  • Its colour is red due to the presence of iron oxide and rich in potash.

Soil || Definition, Types, Importance & Advantages

  • This one porous and unable to hold much water.
  • It is not very fertile but it can be enriched by adding chemical fertilisers.
  • It is fit for growing oilseeds and millets.

4. Laterite Soil

  • It found in regions with heavy rain obtain like parts of Tamil Nadu, Orissa, Andhra and Assam.
  • It appears reddish due to the presence of hydrated oxides of aluminium and iron with quartz grains.

Soil || Definition, Types, Importance & Advantages

  • They are poor in nutrients and needs to be enriched with chemical fertilisers.
  • This one good for plantation of tea, coffee and coconut.

5. Desert Soil

  • It is found in region of Rajasthan and some parts of Gujarat.
  • It is coarse, sandy and porous.

Soil || Definition, Types, Importance & Advantages

  • They can’t retain water therefore, it requires a constant supply of water.
  • It lacks humus content, hence is not very fertile.

6. Mountain Soil

  • It is found in the Himalayan region.
  • Its quality varies with varying heights.
  • Most mountain soils are thin but can be cultivated with the use of fertilisers.

Soil || Definition, Types, Importance & Advantages

  • These are particularly suited for growing orchids.
  • Peat soil is a type of mountainous soil which is rich in humus.

Importance of Soil

  • It is valuable to man for food production.
  • It is also a basic part of wildlife habitats and recreational resources.
  • Various soil organisms like earthworms, bacteria, insects and mammals use this as a natural habitat.
  • Plants obtain water and minerals through this land resource.
  • Plant sources of many medicinal drugs exist here.
  • Wood, fibre, fruits, rubber, oils, dyes and various other economic products which the man uses, all dependent on this land.
  • The very existence of mankind is greatly influenced by this land resource.
  • That’s why it is importance.

Properties of Soil

  • An ideal soil should have the following properties:-
  • Good water – holding capacity
  • Adequate air spaces
  • Good texture obtained by mixing different sized particles.
  • Good amount of humus.

Soil Erosion

  • Soil erosion is the removal of top soil.
  • This is brought about by wind and water or rain.
  • There are several factors which allow water and wind to cause soil erosion. Some of these factors are:-

1. Deforestation

2. Over grazing

3. Poor Farming Methods

4. Forest Fires

1. Deforestation

  • Removal of vegetation that is removal or cutting of trees allows water to runoff the soil.
  • The water carries it particles into the rivers, which get chocked with silt. The net result is floods.

Soil || Definition, Types, Importance & Advantages

  • Since deforestation makes the land barren, wind erosion too takes place.
  • The root system of the plants binds the soil together as well as acts as a channel for water to percolate down, thereby, preventing erosion.

2. Over grazing

  • Over grazing by large animal populations has also destroyed vegetation and resulted in barren lands.

Soil || Definition, Types, Importance & Advantages

  • The barren lands do not hold water any more.
  • In addition, barren lands are liable to erosion by strong winds.

3. Poor Farming Methods

  • Ploughing loosens the soil and destroys its natural structure.
  • Failure to replace humus after successive crops reduces the water holding capacity.

Soil || Definition, Types, Importance & Advantages

  • The soil thus  dries and is blown away by winds.
  • On sloping ground, such soil may be eroded by water.
  • Continuous cropping of land by only one type of crop also adds to loss of fertility.

4. Forest Fires

Soil || Definition, Types, Importance & Advantages

  • Forest fires, too lead to soil erosion.
  • After fire, the soil is exposed to two main factors causing erosion, namely wind and water.

Prevention of Soil Erosion

  • The prevention of soil erosion can be brought about by controlling the factors which cause soil erosion.
  • The methods are as follows:-

1. Deforestation should be stopped.

  • Rather, trees should be planted.
  • Afforestation should be undertaken not only in areas previously cut, but additional areas should be brought under plantation.

2. To reduce the effect of strong winds in the fields, the boundaries of the fields should be planted with trees in two to three rows.

3. To maintain the soil in its natural condition, it is advisable to grow different crops.

4. Proper drainage and irrigation arrangements should be made in the fields.

5. On the sloping areas in hills, strip cropping should be practised, thereby reducing the steepness of the slopes and checking soil erosion.

Uses of Soil

  • It is the medium for plant growth.
  • It is used for recycling of nutrients and wastes.
  • This is used for water supply and purification.
  • Habitat for soil organisms.
  • It is used in the field of engineering.

Let’s Know More

1. Define Loams.

Ans:- A soil containing a mixture of sand, silt and clay is called a loams.

  • It is the best soil for plant growth.

2. What is Percolation rate of soil?

Ans:- The property of soil by which it allows water to seep through it is known as percolation and the amount of water that percolates through soil in a minute is called the rate of percolation.

3. What is Strip – cropping?

Ans:- Strip – cropping means the planting of crops in rows or strips to check flow of water.

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Geothermal Energy

  • Geothermal Energy is a form of renewable energy and independent of sun, having the source of natural heat inside the earth.
  • The term Geothermal comes from two Greek words ‘ GEO ‘ and ‘ THERM ‘.
  • The Greek word ‘ GEO ‘means to the earth while ‘ THERM ‘ meant heat release from the earth.

Geothermal Energy | Definition, Environmental Impact, Advantage

  • It is the energy which obtained from the earth from the hot rocks present inside the earth.
  • It is produced because of the fission of radioactive materials in the earth’s core and some places inside the earth become very hot. Hence, they are called hot spots.

Definition of Geothermal Energy

  • The enormous amount of energy available inside the earth in the form of heat is known as Geothermal energy.

Sources of Geothermal Energy

  • Following are the sources of it:-

1. Hydrothermal resource

2. Vapour dominated resource

3. Hot dry rock resource

4. Geopressure resource

5. Magma resource

1. Hydrothermal resource

  • These are the deposits of hot water and steam at lesser depths and these can be extracted by means of production well.
  • High temperature water and steam is used for the generation of electricity, otherwise it is used for space heating.

Geothermal Energy | Definition, Environmental Impact, Advantage

  • This may be seen that only a part of the rock is permeable constituting the geo-fluid reservoir, so the field is able to produce commercially a viable resource.
  • It simply classified into two parts:

A. Hot Water Fields

B. Wet Steam Fields

A. Hot Water Fields

  • At these locations hot water below 100°C emit out as hot spring and the geothermal aquifers being covered by confining layers to keep the hot water under pressure.
  • For e.g. Sahestra dhara near Dehradun, Sacred kund at Badrinath in Uttarakhand, Pro river valley, etc.

B. Wet Steam Fields

  • The pressurized water is at more than 100°C and contains small quantities of steam and vapour in the geothermal reservoir.
  • Sites where the steam escapes through cracks in the surface are called fumaroles.
  • An impermeable cap-rock prevents the fluid from escaping into atmosphere and drilling is carried out to bring the fluid to the surface.
  • The fluid is used to produce steam and boiling water in predominant phase.
  • For e.g. Low Azufre, Deing, etc.

2. Vapour dominated resource

  • It produces dry saturated steam of pressure above atmospheric pressure and at high temperature about 350°C.
  • Water and steam coexist, but steam is in dominant phase and regulates pressure in the reservoir.
  • Steam obtained from such a geothermal field directly drives a turbine.
  • For e.g. Kamojang, Malsukawa, The Geysers California. etc.

3. Hot dry rock resource

  • This is a geological formation with high temperature rocks at 650°C, heated by conductive heat flow from magma but contains no water.
  • To trap its energy the impermeable rock is fractured and water is injected to create an artificial reservoir.
  • Water circulates and hot fluids return to the surface through the other drilled well as steam and hot water, which are used to generate electricity.

4. Geopressure resource

  • It contains moderate temperature brines containing dissolved methane and these are trapped under high pressure in a deep sedimentary formation sealed between impermeable layers of shale and clay at depths.

Geothermal Energy | Definition, Environmental Impact, Advantage

  • When trapped by boring wells, three sources of energy are available:-

A. Thermal

B. Mechanical as pressure

C. Chemical as methane

5. Magma resource

  • It is a molten rock at temperature ranging from 900°C to 1600°C. This hot viscous liquid comes out from active volcanic vents and solidifies.

Geothermal Energy | Definition, Environmental Impact, Advantage

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Types of Geothermal Energy Power Plants

  • Following are the types of geothermal energy power plants:-

1. Vapour Dominated Power Plant

2. Liquid Dominated Power Plant

1. Vapour Dominated Power Plant

  • In a vapour dominated power plant, steam is extracted from geothermal wells, passed through a separator to remove particulate contents and flows directly to a steam turbine.
  • Steam then operates the turbine coupled with the generator is at a temperature of about 245°C and pressure 7 bar which are less than those in conventional steam cycle plants.
  • Thus, the efficiency of geothermal plants is low, i.e., about 20 %.

Geothermal Energy | Definition, Environmental Impact, Advantage

  • Exhaust steam from the turbine passes through a condenser and the water so formed circulates through the cooling tower.
  • It improves the efficiency of the turbine and controls environmental pollution associated with the direct release of steam into the atmosphere.
  • Waste water from the cooling tower sump is reinjected into the geothermal well to ensure continuous supply.

2. Liquid Dominated Power Plant

  • These plants are also called wet steam plants because they give wet steam i.e., a mixture of hot water and steam under high pressure.
  • There are two types of liquid dominated power plants:-

i. Flashed Steam System

ii. Binary Cycle System

i. Flashed Steam System

  • It is preferred for high temperature mixture of geothermal brine and steam, with low dissolved impurities.
  • Geothermal fluid passes through a flash chamber where a large part of the fluid is converted to steam.

Geothermal Energy | Definition, Environmental Impact, Advantage

  • Dry saturated steam passes through the turbine coupled with the generator to generate electric power.
  • Hot salt water from the flash chamber and the turbine discharge from the condenser are reinjected into the ground and reinjection of the spent brine ensures a continuous supply of geothermal fluid from the well.

ii. Binary Cycle System

  • A binary cycle is utilized where geothermal fluid is hot water with temperature less than 100°C.
  • This plant operates with a low boiling point working fluid in a thermodynamic closed Rankine cycle.

Geothermal Energy | Definition, Environmental Impact, Advantage

  • Hot brine from underground reservoir circulates through a heat exchanger and is pumped back to the ground.
  • In heat exchanger, hot brine transfers its heat to the organic fluid thus converting it to a superheated vapour that is used in a standard closed Rankine cycle.

Environmental Impact of Geothermal Energy

  • Geothermal energy is not completely pollution free energy.
  • The main adverse environmental effects are air pollution, thermal pollution, surface disturbance, physical effects caused by fluid withdrawal.
  • At geothermal site, the air pollution is the major problem because of emission of poisonous gases such as hydrogen sulphide ( H2S ), ammonia, methane, Carbon dioxide ( CO2 ) etc.
  • The extraction of energy from hot dry rocks or molten magma, it is necessary to force water down boreholes as a working fluid and return it to surface to use in turbine.
  • If the underground reservoir is highly permeable, there is no way to know how much water is returned to the surface.
  • A large volume of flash steam getting away into the atmosphere could cause dense fog to occur.
  • At geothermal site, some harmful substances may escape into the air.
  • These may contain radioactive materials also thus systematic monitoring is advisable.
  • Geothermal water contains dissolved solids.
  • The amount of dissolved solids is in the range of 300-1500 ppm of which silica amounts to 25-50 %.
  • The possible solution is reinjection or disposal into sea through ducts and channels and also the use of evaporator ponds.

Types of Geothermal Fields

  • There are three common types of geothermal fields:-

1. Hot Water Fields

2. Wet Steam Fields

3. Dry Steam Field

1. Hot Water Fields

  • Hot water field, containing a water reservoir at temperature ranging 50- 100 °C.
  • Such fields without much steam content can be useful for house heating and agricultural purposes the temperature gradient in this field is less.

Geothermal Energy | Definition, Environmental Impact, Advantage

  • The reservoir contains water in the liquid phase below the boiling point of water under pressure.
  • On the surface, there are often thermal springs whose temperature is near the boiling point of water. These fields occur at depth less than 2 km.
  • The geyser plant of USA is the largest plant in the world today.

2. Wet Steam Fields

  • The wet steam fields contain pressurized water in reservoir at temperature higher than 100°C.
  • When hot water at high pressure is brought to the surface, its pressure is sufficiently reduced and some water will get flashed into steam and remaining in the form of boiling water.
  • The resulting mixture is a mixture of water and steam. Such fields are suitable for power generation.

Geothermal Energy | Definition, Environmental Impact, Advantage

  • When the well is drilled at such locations, the pressurized water rises into well because of less pressure above the well.
  • The vapour is used directly for producing power while the hot water gets separated in the separator and is used for thermal applications.
  • The percentage of steam generated depends upon the available geothermal fields and more than 90 % of hydrothermal reservoirs exploited on industrial scales.

3. Dry Steam Field

  • These fields are similar to wet, steam fields but heat transfer from the depth is much higher.
  • These reservoirs produce superheated steam at pressure above atmosphere.
  • The permeability of these fields is lower than wet fields.

Geothermal Energy | Definition, Environmental Impact, Advantage

  • When the well is drilled up to the reservoir and extraction of fluid starts, a depressed zone is formed at the bottom of the well, that enhances the boiling of water surrounding the rocks.
  • The steam flows through the dry bottom area and starts expanding and gets cool. But the heat added by surrounding rocks at high temperature keeps the steam at superheated state.
  • The degree of superheating may reach up to 100°C.

Comparison Between Geothermal Power Plant & Thermal Power Plant

S.NO. Geothermal Power Plant Thermal Power Plant
1. It uses inexhaustible source of energy. It uses exhaustible source of energy.
2. It is more environment friendly. It is less environment friendly.
3. These power plants in some dangerous cases can cause earthquakes. There is no much problem.
4. It is mainly used for power generations process. It can be used for various industrial processes.
5. Setup cost is high. Setup cost is low.
6. By products of those plant are not used. By products of these plant can be used.
7. These plants are less flexible. These plants are more flexible.
8. Specified area are required. No such restriction.

Geothermal Energy Scenario in India

  • There are around 340 known thermal areas in India, each represented by hot or warm springs.
  • Many more areas are being discovered and reported, in the 12 well defined geothermal energy provinces.
  • The total stored heat potential of the 93 systems considered is 36.87 × 1018 calories, which is equivalent to the combustion energy of 5160 million tones of coal or 25440 million barrels of oil. 38 of these frameworks are of high temperature type whose heat energy could be considered for electrical power generation.
  • Their estimated cumulative potential for power generation is of the order of about 500 MW for 100 years or 1650 MW for a 30 years period of utilization.
  • Of the remaining thermal areas, 49 are of intermediate temperature and 6 are of low temperature geothermal energy resources type which could best be used for non- electrical applications.
  • Their cumulative stored heat potential is 19.37 x 108 calories out of which only 1.135 x 108 calories could be beneficially put to practical utilization.
  • Since most of the non – transportation energy needs could be met at temperature below 150 – 200 °C and if the potentials of all 93 systems are considered for non – electrical applications the cumulative beneficial heat will be of the order of 2.185 x 108 calories.
  • If this heat is to be supplied from electrical power, 10,000 MW of electricity could be required for 30 years period. Thus these springs have a potential to substitute about 10,000 MW of electricity could be required for 30 years period.
  • This is roughly 10 % of the total anticipated power production in India by the turn of the century.
  • Several pilot projects were undertaken by Geological Survey of India in collaboration with other agencies such as N. A. L. Bangalore, IIT Delhi in the geothermal energy area of North – West Himalayan province, which have conclusively proved the vast potentialities for exploitation.
  • A pilot project for ” space heating ” at Puga, in Ladakh in 1975 at an altitude of 4500 m, involved construction of a shed and using steam at 125 °C , at 2.5 kg/ cm² from a nearby geothermal energy well for heating the space, with the help of an aluminium finned, copper, tube radiator converter.
  • A difference of 25 °C was achieved with respect to the ambient temperature.
  • Another project named ” Green house pilot project ” at Chumathang, in 1974, was commissioned.
  • It utilizes hot water from a nearby geothermal energy well to heat the soil and environment of a green house separately.
  • Heating of soil was done by laying zig – zag pipes below the complete area of soil and allowing geothermal energy fluid to pass through them.
  • This project proved that 41 varieties of plant including flowers, creepers, vegetables, and trees can be grown even at the peak of winter using geothermal energy and constructing green house, whereas normally no germination is possible for 10 months in a year in this area.
  • This project was undertaken by Geological Survey of India in collaboration with ” Field Research Laboratory “ at Leh.
  • A third pilot project ” cold storage plant “ has been recently commissioned at Manikaran by the joint collaboration of Geological Survey of India, IIT Delhi, and Himachal  Pradesh Government.
  • This plant avails the hot water at 90 °C from a nearby geothermal energy well and cold water at 10 °C from the Parbati river, flowing nearby, and is capable of removing 400,000 kcal/hr of heat to obtain a permanent cold storage temperature of 5 °C.
  • This can only possible if successful help the local farmers to store nearly 15,000 tonnes of fruits and potatoes after the harvest and enable them to sell them throughout the year at a uniform price.
  • A 5 kw pilot power plant is under fabrication at National Aeronautical Laboratory, Bangalore.
  • This plant will run on geothermal energy which will be recovered from the hot springs at Manikaran in Himachal Pradesh. This will utilize a binary cycle process using R – 113 as the working fluid.
  • All these studies have confirmed the suitability of the resources for utilization for various purposes. Plants are being made to undertake further research and development studies in the area of geothermal energy.

Applications of Geothermal Energy

  • Generation of electric power.
  • Industrial process heat.
  • Space heating for buildings.
  • Production of salt from sea.
  • Extraction manufacturing.
  • Textile industry.
  • Sewage heat treatment.
  • Geothermal water is utilized for greenhouse cultivation using discharge water from a geothermal energy drill hole.

Advantages of Geothermal Energy

  • Feasibility of modular approach represents a lot of opportunities for improvement of relatively quick, cost effective geothermal energy projects.
  • The emission of CO2 and SO2 by geothermal energy plants is far less compared with conventional fossil fuel based power plants.
  • It is almost pollution free.
  • It is an inexhaustible source of energy.
  • More dependable source of power generation than other renewable energy sources.

Disadvantages of Geothermal Energy

  • Geothermal fluids often contain significant quantities of gases such as CO2, CH4, N2, NH3 and H2S. The H2S as well as dissolved chemicals can sometimes be acidic. Due to this, corrosion, erosion and chemical deposition may be issues which require attention at the design stage and during operation of the geothermal energy system.
  • Noise pollution because of drilling.
  • Well casings and pipelines can endure erosion and / or scale affidavit, and turbines, especially blades, can suffer damage leading to higher maintenance costs and reduced power output.
  • Plants are located at far distance from location of application. This causes more losses in power as well as thermal losses or pressure drops in pipe, while transferring hot fluids for direct use.
  • The underground water depletion may occur at low rainfall areas if water is not reinjected back.

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Light

  • Light enables us to see things around us.
  • This is a form of energy that we can detect with our eyes.
  • It falls on objects, bounces off from their surfaces and reaches our eyes.
  • It is the light that causes the sensation of vision in us.

Light || Definition, Nature, Reflection & Properties

  • For example, the sun gives out light, therefore we can see the sun.
  • It takes about 8.3 minutes to reach the earth from the sun.
  • Thomas Alva Edison was the first person who invented electric light bulb.

Definition of Light

  • Light is a form of energy which enables us to see objects which emit or reflect light.
  • We get it from various sources, e.g. sun, electric lamp, candle, and oil lamp, etc.

Characteristics of Light

  • It is an electromagnetic wave.
  • It is a transverse wave, and does not need any medium to travel.
  • They can travel through vacuum.
  • Its speed through vacuum is 3 x 108 m/s.
  • There velocity changes when it travels from one medium to another. While frequency remain same in all medium.
  • It can pass through transparent materials, such as glass or air.
  • They travel in a straight line.
  • It gets reflected back from polished surfaces, such as mirrors, polished metal surfaces, etc.
  • It undergoes refraction when it travels from one transparent medium to another.

Rectilinear Propagation of Light

  • There are a number of everyday phenomena which suggest that light travels in straight lines:-
  • Formation of day and night suggests.
  • Formation of shadows suggests.
  • When a beam of sunlight enters a dark room through a ventilator, we can see the light.
  • When the head light of a car is switched on, there rays appear to travel in straight lines.
  • The burning candle flame, it appears as if it is giving out a few beams of light.
  • Beams of light coming from the projection room in the cinema hall.
  • The ray coming from small laser torches used as pointers.
  • Above all the given examples are suggest that light travels in a straight line.
  • Rectilinear propagation of light refers to the property of light travelling in a straight line.
  • Also read on touching the link:-

Solar Cell in details

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Heat Treatment

Heat Transfer

Energy

Heat

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Nature of Light

  • There are two theories about the nature of light:-

1. Wave theory 

2. Particle theory 

1. Wave theory

  • According to wave theory, light consists of electromagnetic waves which do not require a material medium for their propagation.
  • The wavelength of visible light waves is very small i.e only about ( 4× 10-7  to 8 × 10-7  )m.
  • The speed of light wave is very high.
  • And it tells about the phenomena of diffraction ( bending of light around the corners of tiny objects), interference and polarization of light.

2. Particle theory

  • According to the particle theory, light is composed of particles which travel in a straight line at very high speed.
  • It tells about the phenomena of reflection and refraction of light, and casting of shadows of objects. 

Conclusion

  • In the past hundred years of physics experiment have demonstrated that light has a dual nature, it exhibits the properties of both waves and particles.
  • The modern theory of light called “Quantum Theory of Light”. It combines both the wave and particle models of light.

Ray and Beam of Light

  • A straight line drawn in the direction of propagation of light is known a ray of light.
  • A ray is described by a straight line with an arrow- head pointing in the direction of propagation of light.
  • A bundle of the adjacent light rays is called a beam of light.
  • A beam of light can be 
  • Parallel beam 
  • Convergent beam
  • Divergent beam of light.
  • The beam of light in which all the rays are parallel to each other is called parallel beam of light.

Divergent_Beam_of_Light

  • The beam of light in which the rays of light starting from a point source move out in different directions is called a divergent beam of light.

Convergent_Beam_of_Light

  • The beam of light in which the rays of light starting from a large source of light get closer to each other is called convergent ray of light.

Reflection of Light

  • When a ray of light falls on a polished smooth surface, such as a mirror, it return back into the same medium.
  • Hence, the bouncing back of light after striking the surface of an object is called reflection of light.
  • Different materials reflect light to different extent.
  • Silver is one of the best reflectors of light.
  • We see our images in a mirror due to reflection of light.

Light || Definition, Nature, Reflection & Properties

  • The ray of light which falls on a cleaned surface is called the incident ray of light.
  • The ray of light which gets reflected from a polished surface is called the reflected ray of light.
  • The normal is a line at right angle to the reflecting surface, such as, a plane mirror, at the point of incidence.
  • The angle made by the incident ray with the normal is known the angle of incidence( <i ).
  • The angle made by the reflected ray with the normal is called the angle of reflection( <r ).

Kinds of reflection

  • Depending on the nature of the reflecting surface, there could be two kinds of reflections:-

1. Regular reflection

2. Irregular reflection

1. Regular reflection

Regular_Reflection

  • The reflection of light from a mirror- like smooth reflecting surface so that the reflected rays are parallel to each other is called regular reflection.
  • It is also known as specular reflection.

2. Irregular reflection

Irregular_Reflection

  • The reflection of light from a rough, irregular surface randomly in various directions is called irregular reflection.
  • It is not parallel to each other.
  • It is also called diffused reflection.

Laws of Reflection of Light

  • The reflection of light from a plane surface or from a spherical surface takes place according to the two laws, which are known as the laws of reflection.

1. First law of reflection

2. Second law of reflection 

Light || Definition, Nature, Reflection & Properties

1. First law of reflection

  • The angle made by the incident ray with the normal at the point is equal to the angle made by the reflected ray with the normal, i.e.

Angle of incidence = Angle of reflection

<i = <r

2. Second law of reflection

  • The incident ray, the reflected ray and the normal at the point of incidence, all lie in the same plane.

Images formed by reflection

  • The images formed by the reflection, it may be real or virtual.

1. Real image

  • When the rays of light starting from a well illuminated object are reflected from a smooth polished surface in such a way that they meet at some other point or on a screen, then image so formed is called real image.
  • A concave mirror gives a real image if the object is placed at or beyond focus.

Following are the characteristics of a real image:-

  • It can always be taken on screen.
  • It is always inverted as compared to the object.
  • It may be of the same size/bigger/smaller than the object.

2. Virtual image

  • When the rays of light starting from a well illuminated object are reflected from a smooth polished surface in such a way that they appear to meet at some other point, but cannot meet on a screen, then the image so formed is called virtual image.
  • The image formed in a looking glass is always virtual.

Following are the characteristics of a virtual image:-

  • It cannot be taken on a screen.
  • It is always erect as compared to the object.
  • It may be of the same size/bigger/smaller than the object.

Refraction of Light

Refraction_of_Light

  • We know that light travels in straight line through any medium of uniform density.
  • However, when a ray of light travels from one transparent medium to another, it suffers a change in its direction.
  • For e.g, air to glass, etc.
  • The change in direction of a ray of light when it passes from one medium to another, is called refraction of light.
  • Its speed through glass is 2 x 108 m/s.

or

  • The bending of a ray of light when it passes from one medium to another, is called refraction of light.
  • The direction in which the ray of light bends when it travels from one medium to another depends upon the optical density of the two media.

Bending_of_Ray_Due_to_Refraction

  • When a ray of light goes from an optically rarer medium to an optically denser medium, it bends towards the normal. i.e.

Angle of refraction( <r ) < Angle of incidence ( <i )

  • When a ray of light goes from an optically denser medium to an optically rarer medium, it bends away from the normal. i.e.

Angle of refraction ( <r ) > Angle of incidence (<i )

  • Air is optically less denser than water or glass. Therefore
  • A ray of light travelling from air into glass bends towards the normal.
  • A ray of light travelling from glass into air bends away from the normal.

Laws of Refraction of Light

  • There are two laws of refraction:-

1. First law of refraction

2. Second law of refraction

Laws_of_Refraction

1. First law of refraction

  • It tells about the ratio of sine of the angle of incidence to the sine of the angle of refraction for a particular pair of media is constant.
  • Hence, if the angle of incidence is i, and that of refraction is r, then

sine of the angle of incidence/ sine of the angle of refraction = sin i/ sin r = constant

  • The value of this constant depends upon temperature and the wavelength of light used in the measurement.
  • It is also known as Snell’s law.

2. Second law of refraction

  • It tells that the ray, the refracted ray and the normal at the point of incidence, all lie in the same plane.

Cause of Refraction of light

  • The speed of light depends on the nature of the medium in which it travels.
  • When it travels from a rarer medium to a denser medium, its speed decreases.
  • Whereas speed of light increases when it travels from a denser to a rarer medium.
  • It is due to this change in the speed of light that the ray of light bends as it goes from one medium to another.
  • Thus, the change of speed of light as it travels from one medium to another is the cause of refraction.

Effects of Refraction of Light

  • A stick held obliquely and partly immersed in water, it appears to be bent at the water surface.
  • An object submerged under water appears to be raised.
  • A pool of water is appeared to be less deep than it actually is.
  • When a thick glass slab is placed over some printed matter, the letters seem raised when viewed from the top.
  • A lemon is kept in water in a glass tumbler appears to be bigger than its actual size, when viewed from the sides.
  • The stars appear to sparkle on a clear night.

Let’s known more

1. Define luminous objects.

Ans:- The objects which emit light themselves are called luminous objects.

  • Luminous objects may be natural or man-made.

2. Define non-luminous objects.

Ans:- Those objects which do not emit light themselves but only reflect ( or scatter ) the light which falls on them, are called non-luminous objects.

  • Even the moon is a non-luminous objects. We can see the moon because it reflects the sunlight falling on its surface towards us.

3. What is transparent medium?

Ans:- A medium in which ray can travel freely over large distances is called a transparent medium. For e.g. water, glycerine etc.

4. What is opaque?

Ans:- A medium in which ray cannot travel is called opaque. For e.g. wood, metals, bricks, etc.

5. Define medium.

Ans:- The material through which ray travels is called medium.

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Heat

  • The term Heat is a common noun.
  • In English it is heat or warmth.
  • In French chaleur, German warme, Latin calor etc.
  • Heat is a form of Energy which can be felt but cannot seen.
  • It causes the feeling of hotness or coldness.

Heat || Definition, Sources, Characteristics and Applications

  • It always moves from a warmer place to a cooler place.
  • These pass from a body at higher temperature to a body at lower temperature.
  • Heat presents only at the boundary while the change takes place inside the system.
  • It affects the movement of the molecules or particles in matter.
  • The first scientist James Prescott Joule who discover that heat is a type of energy.

Definition of Heat

  • Heat is a form of energy that flows from a hot body to a cold body.
  • It is represented by the symbol Q.
  • Its SI unit is joule. And another common unit is the calorie ( cal ).
  • 1 cal = 4.184 J

Sign Convention

  • If warmth flows from the system to surroundings, the quantity is said to be positive and if it flows from surroundings to system it is said to be negative.

In the other words,

  • Heat received by system = +Q
  • Heat rejected by system  = −Q

Sources of Heat

  • The following are the main sources of warmth:-

1. Sun

2. Fuels

3. Friction

4. Explosions

5. Electric Heater

6. Volcanic eruption

1. Sun

Heat || Definition, Sources, Characteristics & Applications

  • The sun is the ultimate source of heat for all the living beings on the earth.
  • Plants use the energy of the sun to prepare their food.
  • Human beings are able to survive by the warmth of the sun.

2. Fuels

Heat || Definition, Sources, Characteristics & Applications

  • It produce energy when they burn.
  • In the fuels wood, coal, kerosene, petrol, and cocking gas are some of the commonly used.
  • The warmth is produced by burning fuels is also used to derived the engines as well as to run the cars and to generate electricity.

3. Friction

Heat || Definition, Sources, Characteristics & Applications

  • It is a kind of force that produces warmth.
  • When we rub our palms, they become warm.
  • A matchstick catches fires, when struck, due to friction.

4. Explosions

Heat || Definition, Sources, Characteristics & Applications

  • This is phenomenon resulting from sudden release of energy which is dissipated by a blast wave, by translocation of the objects in the space or by warmth generation.
  • It may be supersonic.
  • It is not as fast as the speed of sound.
  • They classify into three types:-

1. Atomic

2. Chemical

3. Mechanical

5. Electric Heater

Heat || Definition, Sources, Characteristics & Applications

  • In cold weather, the electric heater provides warmth.
  • We use geysers or water heaters to warmth the water.
  • A filament is present in all these appliances.
  • Electricity heats up the filament which emits warmth.

6. Volcanic eruption

Volcanic Eruption

  • It produces internal heats from natural radioactivity.
  • It happens when hot materials are thrown out of a volcano.
  • Also read on touching the link:-

Solar Cell in details

Networking in details

Green Concrete in details

About related to machine click on the link

Lathe machine

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Heat Treatment

Energy

 Characteristics of Heat

  • It has no shape, no mass, no colour, no odour, no volume and no weight.
  • It is an invisible from of energy.
  • The presence of warmth is left only through its effect on matter.
  • It might be transferred from one body to another.
  • They flow in all directions.
  • It might be transformed into other forms of energy. For example, they can be changed to light energy, on heating iron, it becomes red hot and emits light.
  • They can also be converted into mechanical energy. For example, steam can move an engine.
  • Conversely, other forms of energy can be transformed into warmth energy.
  • For example, on burning a candle, the chemical energy is transformed into warmth and light energy.
  • When we switch on an electric bulb, the electrical energy gets transformed into warmth and light energy.

Flow of Heat

Heat    

HOT object         COLD object

Flow

  • Suppose we keep two bodies in contact with each other.
  • The flow of warmth from one body to another takes places.
  • It is from hot object to a cold object.
  • For example, mixing sugar in hot milk makes the spoon warm.
  • When we touch the object, warmth flows from one body to the other.
  • We feel cool when we touch the ice cubes. It is because our hand is hotter than the ice.
  • On touching the ice cubes, warmth flows from our hand to the ice and we feel cold.
  • Suppose we touch the water taken from a geyser, we feel hot.
  • It is because the water taken from the geyser is hotter as compared to our normal body temperature.
  • On touching this hot water, warmth flows from the water to our hand. As a result, we feel hot.
  • When a hot body comes in contact with a cold body, it is observed after some time the hot body loses some of its warmth and the cold body also becomes less cold.
  • This is because of the transfer of warmth in both objects.

Transfer of Heat

Heat_Transfer

1. Conduction

2. Convection

3. Radiation

1. Conduction

  • It is a process of transferring warmth from the hot end to the cold end from particle-to-particle of the medium.
  • Thus, a medium is needed for the transfer of warmth by conduction.
  • It mainly occurs in solids.
  • The conductions that must be fulfilled so that the flow/transfer of warmth takes place by the conduction process:-
  • A difference of warmth exists between two bodies or two ends of the same body.
  • The two bodies at different points are in direct contact with each other.

2. Convection

  • It is the process of transfer of warmth by the actual movement of the particles of the medium.
  • Liquids and gases are mainly heated by convection as they are insulators of heat.
  • Solids cannot be heated by convection as their particles are very tightly packed.
  • Hence, they are unable to move.
  • For examples, when you light a candle, the air above it gets heated and moves upwards.

3. Radiation

  • It is a process of warmth transfer in which warmth passes directly from one body to other without affecting the medium.
  • This means that no medium is needed for warmth transfer in the process of radiation.
  • In vacuum, warmth transfer occurs only by the process of radiation.
  • For example, we feel warm when we are in the sun.

Heat and Temperature

  • Warmth and Temperature are two different concepts.
  • Warmth causes temperature. Thus, there exists a cause effect relation between them.
  • It is the cause and temperature is the effect.
  • For example, when the body is heated, its temperature increases.

Differences Between Heat and Temperature

S. NO. Heat Temperature
1. This is a form of energy. It is the quantity that determines the degree of hotness or coldness of a body.
2. It is responsible for temperature. There can be no temperature without warmth.  Temperature is one of the effects of heat.
3. It raises the temperature of the body. It does not determine the direction of flow warmth. It determines the direction of flow of warmth, i.e., from a body at a higher temperature to a body at a lower temperature.
4. The direction of transfer of warmth does not depend on the quantity of warmth. The direction of transfer of warmth depends on the temperature.
5. It is measured in joule or calorie. It is measured in degree Celsius( °C ) or degree Fahrenheit ( °F ).

Application of Heat

  • It is used in a bell in the circuit rings to warm of a fire.
  • For cold application it is most often used for sport injury.
  • It is also used in the field of indications like comfort and relief, Ache and pain, etc.
  • To determine the client ability to tolerate therapy.

Let’s known more

1. Define Thermal Equilibrium.

Ans:- When two bodies are in contact with each other and no warmth flows through them, they are said to be in the state of thermal equilibrium.

  • The exchange of warmth between them is zero.

2. What is insulators of warmth?

Ans:- Those substance which do not allow warmth to pass through them easily. They are called insulators of warmth.

  • For examples, wood, plastic, mud, cork, cotton, wool, etc.

3. What is conductors of warmth?

Ans:- Those substance which allow warmth to pass through them easily. They are called conductors of warmth.

  • For examples, copper, silver, iron, mercury, etc.

4. Define Black surfaces.

Ans:- It absorb more radiation than white and shiny surfaces.

External Link 

Energy

  • Energy, it is the word which comes from the Greek language.
  • This is an ancient Greek word romanized from energeia operation.
  • It was possibly appears in 4th century BC in the first time the work of Aristotle.
  • Thomas Young was the first person who use the term “Energy” in modern sense in 1807.

Energy || Definition, Types, Sources, Forms, Examples & Uses

  • The source of energy is the Sun for most of life on the earth.
  • The Sun derives its energy in the form of Nuclear fusion in its core.
  • Energy is required for every living organism on the earth, without this human can not work without a single step.
  • It is a scalar quantity.
  • It has only magnitude but no direction.

Definition of Energy

  • The ability to do work is called energy.
  • Example- Cut a log of wood into small pieces, a moving cricket ball,etc,.
  • There SI unit is joule which is denoted by J.
  • Joule is the smaller unit.
  • Kilo -joule is the bigger unit of Joule.

            1 kilojoule =1000 J

                      1 kJ = 1000 J

  • Joule is named on a British physicist James Prescott Joule.

Law of conservation of energy

  • This states that it can be neither created nor be destroyed.
  • According to the 1st law of thermodynamic, this states that a closed system’s energy is constant unless it is transferred in or out by work or heat, and that no energy is lost in transfer.

Also read on touching the link:-

Solar Cell in details

Networking in details

Green Concrete in details

About related to machine click on the link

Lathe machine

Capstan Lathe

Heat Transfer

Heat Treatment

 Types of Energy

On the basics of mechanical energy, it is of two types:-

1. Kinetic Energy( KE )

2. Potential Energy( PE )

1. Kinetic Energy( KE )

Kinetic_Energy

  • The energy of a body due to its motion is term as KE.
  • It means that a moving object can do work on another object when it strikes.
  • For example- A moving cricket ball possesses KE, moving water, etc.
  • The KE of a moving body measures from the amount of work it can do before coming to rest.

Formula

                      KE = ½× mv²

Here,

          m = mass of the body

           v = velocity of the body

From this formula, it clear that:-

i. The KE of a body is directly proportional to the mass of the body.

ii. The KE of a body is directly proportional to the square of the velocity of the body.

2. Potential Energy( PE )

Potential_Energy

  • The energy of a body due to its position or change in shape is known as PE.
  • Scottish engineer and William Rankine was 1st the physicist who introduce the term PE in 19th century.
  • PE associates with the forces that act on a body in a way that the total work done by these forces on the body depends only on the initial and final positions of the body in space.
  • For example – A flying bird, a flying aeroplane, etc.

Formula

                       PE = mgh

Here,

           m = mass of the body

            g = acceleration due to gravity

            h = height of the body above a reference point, say the surface of the earth

Source of Energy

  • There are different sources of it : –

Sources_of_Energy

1. Oil 

2. Coal

3. Uranium

4. Biomass

5. Fossil Fuels

6. Wood Fuel

7. Natural Gas

8. Wind Power

9. Solar Power

10. Tidal Power

11. Wave Power

12. Geothermal

13. Marine Current etc.

Types of Sources of Energy

  • On the basics of sources, it can be divided into two types :-

1. Non – Renewable Sources

2. Renewable Sources

1. Non – Renewable Sources

  • These are the sources of energy which are exhaustible i.e., cannot be replaced if once they are used.
  • It is also know as conventional sources.
  • This sources are dug out from the earth.
  • They are present in a limited amount in the earth.
  • For example – Oil, Fossil Fuels, Coal, Petroleum, Natural gas, Nuclear Fuels, etc,.

2. Renewable Sources

  • These are the sources of energy which are inexhaustible i.e., can be used to produce it again and again.
  • It is also know as Non – conventional sources.
  • These sources can be used again and again.
  • For examples:- Sun, Water, Animal dung, Agro- waste, Wood, Bio- gas, etc,.

A good source of energy would be one

  • Which has high calorific value.
  • Which is cheap and easily available.
  • Be easy to store and transport.
  • Eco -friendly.
  • Less combustible.
  • Which does not cause environmental pollution.

Forms of Energy

 

  • They exist in many forms. The main forms of it are:-

Forms_of_Energy

1. Kinetic Forms       

2. Potential Forms

3. Chemical Forms

4. Electrical Forms

5. Thermal (Heat) Forms

6. Light Forms

7. Sound Forms

8. Nuclear Forms

 

1. Kinetic Forms( KE )

  • The energy of a body due to its motion is term as KE.
  • For example:- a moving cricket ball, shooting a rubber band, etc,.

2. Potential Forms( PE )

  • The energy of a body due to its position or change in shape is known as PE.
  • For example- Drawing a Bow, A Bird sitting at a height, etc,.

3. Chemical Forms

  • It releases through a chemical reaction.
  • Examples- gas stoves, water heaters, etc,.

4. Electrical Forms

  • This is caused by moving electric charges called electrons.
  • It is also a form of KE.
  • Example- Solar, Fossil Fuels, etc,.

5. Thermal (Heat) Forms

  • It is a form of energy transfer.
  • It generates from the vibration of atoms and molecules within substances.
  • They also know as Heat Energy.

6. Light Forms

  • It is a form of electromagnetic radiation.
  • It consists of photons, which are produced when an object’s atoms heat up.
  • Light travels in the form of wave and it is the only form of vitality visible to the human eye.

7. Sound Forms

  • It is the form of vitality that can be heard by humans.
  • Sound is a mechanical waves and it produced when a force makes an object or substance vibrate.
  • For Example- air and water, etc,.

8. Nuclear Forms

  • It comes from the splitting of uranium atoms. This process is term as Fission.
  • It creates heat to produce steam.
  • Example- Nuclear Medicine, etc,.

Uses of Energy

  • For lightning.
  • To run the machines.
  • In the field of transport.
  • Its also used in the medical field.
  • It used in the field for making food.
  • For agricultural work and industrial activities.

Advantages and Dis advantages of Energy

S.NO. Advantages  Dis advantages
1.  It is free. Must be able to withstand.
2.  It is renewable. Expensive build.
3.  They don’t expensive to operate and maintain. Its hard to produce same amount.
4. There are no greenhouse gases. Its harvesting is not appropriate for large scale.

Let’s Know more

1. Define Calorific Value.

Ans:- The amount of heat generated by burning a unit mass of the fuel completely is know as its calorific value.

2. Define Fossil Fuel.

Ans:- A natural fuel formed deep under the earth from the pre- historic remains of living organisms is called a Fossil Fuel.

External Link

 

Solar Cell

  • Solar Cell is an energy conversion device which are used to convert sunlight to electricity by the use of the photovoltaic effect.
  • This is also known as photovoltaic cell ( PV Cell ).
  • The term Solar Cell designates to capture energy from sunlight, where PV cell is referred to an unspecified light source.
  • The first practical solar cell was produced in 1954 using Selenium (Se).
  • This solar cell could convert only 1% solar energy into electricity.

Solar Cell || Definition, Working, Types, Applications & Advantages

  • Present day solar cells have efficiency as high as 25%.
  • Now a days, Solar cells are usually produced from semiconductors, such as Silicon and Gallium.
  • A single Solar cell produces very small current at a small potential difference.
  • So, for practical use, a large number of such solar cells are connected together.
  • A combination of a large number of solar cells is called a solar cell panel.
  • Albert Einstein is known as the father of solar cells.

Solar Cell Definition

  • A device which converts the sunlight directly into electricity is called a solar cell.
  • Solar Cells are often coated with transparent thin film of silicon monoxide (SiO) to minimise the reflective losses from the surface.

Solar cells panel

  • A solar cell panel can provide stronger currents under high potential difference.
  • They use for producing electricity for use in space stations and artificial satellites.

Solar Cell || Definition, Working, Types, Applications & Advantages

  • They are very useful in remote and isolated locations.
  • Solar cell panels are being used to produce electricity for:-

i. Street light in rural areas.

ii. Operating radio and TV sets.

iii. Lighthouses and offshore drilling rig operations.

iv. Operating water pumps for domestic and agricultural purpose.

Also read on touching the link:-

Networking in details

Green Concrete in details

About related to machine click on the link

Lathe machine

Capstan Lathe

Heat Transfer

Solar Cell Materials

  • The Solar cells is made of different material and silicon and silicon uses for nearly 90% applications.
  • The choice of material depends on the band energy gap, efficiency and cost.
  • The maximum efficiency of solar cells is achieved with the band gap energy of 1.12 eV -2.3 eV.
  • The various materials like 

1. Aluminum Silicon, Si ( 1.12eV )

2. Aluminum Antimonide, AlSb ( 1.27eV )

3. Cadmium Telluride, CdTe ( 1.5eV)

4. Zink Telluride, ZnTe ( 2.1eV )

5. Cadmium Sulphide, CdS ( 2.42eV ) etc. are the materials suitable for solar cells.

  • The smaller the energy gap, the large number of photon of solar spectrum will be useful to produce the required energy for electrons to jump the forbidden band gap.

Working of Solar Cell

Working_of_Solar_Cell

  • Solar cell is an electric cell that converts sun’s electromagnetic energy into usable electrical energy.
  • It is a semiconductor device and sensitive to photovoltaic effect.
  • Solar cells normally consists of single crystal silicon P-n junction.
  • When photons of light energy from the sun fall on semiconductor junction, the electron-hole pairs are created.
  • Holes pass to the P– region and electrons pass to the N– region.
  • The displacement of free charge creates an electric current when the load is connect across the terminals.
  • This is the basic principle on which the solar cells work and generates power.

Note:

  • Semiconductors are materials, which become electrically conductive when supplied with heat or light, but which operate as insulators at low temperatures.

Construction of Solar Cells

  • In a solar cell, the pinnacle layer is present which includes an anti -reflective cover glass.
  • This glass guards the semiconductor materials against the sunlight.
  • In a solar cell, small grid patterns with slight metallic strips are available under the glass.
  • So, that the top layer of cell can be formed by using the glass, metallic strips & anti- reflective coat.
  • The most important part of this cell is the middle layer where solar energy can form through the effect of photovoltaic.

Construction_of_Solar_Cell

  • They consist of two semiconductor layer which are made up of P- type and N– type materials.
  • The base layer of the cell consists of two parts.
  • A rear metallic electrode is beneath the P– type semiconductor and it works with the metallic grid to generate an electric current in the pinnacle layer.
  • A reflective layer is the last layer in the cell which use to decrease the loss of light within the system.

Types of Solar Cells

  • According to types of crystal, the solar cells are of three types:-

1. Mono crystalline silicon cells ( band gap 1.12 eV )

2. Polycrstalline silicon cells ( band gap 1.12 eV )

3. Amorphous silicon cells ( band gap 1.75 eV )

1. Mono crystalline silicon cells ( band gap 1.12 eV )

  • In Mono crystalline silicon cells, silicon is dope with boron to produce P- type semiconductor.
  • Mono crystalline rods are extracted from silicon and then sawed into thin plates or wafers.

Monocrystalline_Silicon_Cell

  • The upper layer of the wafers dope with phosphorous to produce N- type semiconductor. Then it becomes P-n junction.
  • Maximum efficiency is 24%.

2. Polycrstalline silicon cells ( band gap 1.12 eV )

  • In polycrystalline cells, liquid silicon pour into blocks that are sawed into plates.
  • During solidification of the material, crystal structures of varying sizes are form.
  • The size of crystallites mainly depends upon the cooling condition.

Polycrystalline_Silicon_Cell

  • If the molten silicon is cool very slowly, the crystallites of larger size are gain.
  • The silicon solar cells made from polycrystalline silicon are low cost but low efficiency.

3. Amorphous silicon cells ( band gap 1.75 eV )

  • It is the non- crystalline form of silicon used for solar cells and thin- film transistors.
  • Its layer thickness is less than 1µ, so production costs are lower due to the low material costs.

Amorphous_Silicon_Cell

  • The efficiency of amorphous cells is much lower than that of the other cells.
  • Maximum efficiency is 13%.

Solar Cell Properties

  • Open circuit voltage (Voc)
  • Short circuit current (Isc)
  • Maximum power
  • Efficiency

Factor affecting Solar Cell Performance

  • Light intensity ( type of light)
  • Light wave length (color of light)
  • Angle of incident light
  • Surface condition of solar cells (cleanness)
  • Temperature on solar cells 

Efficiency of Solar Cell

  • The amount of power available from a PV device is determine by

– Its type and area of the material

 The intensity of the sunlight

  The wavelength of the sunlight

  • The efficiency of single crystalline solar cells is 25%.
  • The efficiency of Poly -crystalline silicon cell is less than 20%.
  • Amorphous silicon solar cells is less than 10%.
  • Cells are connect in series to form a panel to provide larger voltages and increased current.

Application of Solar Cells

  • Its mostly use in the field of toys, watches, etc.
  • They also use in the field of electric fence.
  • Its also use in the field of Remote lighting systems area.
  • This may be use in the field of portable power supplies
  • They mostly use in the field of satellites.
  • They also use in the field of water treatment & pumping.
  • Its may be use in the field of emergency power.

Advantages of Solar Cell

  • It is a renewable source of energy.
  • Its free of charge.
  • It doesn’t cause pollution.
  • They can be use in remote areas.
  • The system has long life of 10- 15 years or more.
  • The energy cost is very low because the sources are available freely.
  • More Solar energy in summer.

Dis advantages of Solar Cell

  • It needs lots of space.
  • High initial cost.
  • No Solar power at night & cloudy days.
  • Less Solar energy in winter.
  • DC equipment are expensive.

Let’s Known More

1. What is a solar heater?

Ans:- A solar heater is a device which is use for heating water by utilising the heat energy of the sunlight.

2. What is the Solar heating device?

Ans:- A device which is use for collecting heat radiation of the sunlight in a small region is term as a solar heating device.

3. Name any two components of solar radiation that are not visible to us.

Ans:- The two components of solar radiation that are not visible to us are:

  i. Infrared radiation

  ii. Ultraviolet radiation

4. What is Solar energy?

Ans:- The light and heat energies of the sunlight are collectively term as a Solar energy.

5. What are the traditional applications of solar energy?

Ans:- i. For drying clothes

          ii. For making salt from sea

          iii. For reducing the moisture content of food grains

          iv. For sun- drying of vegetables, fruits, fish, etc.

6. What is Solar cell panel?

Ans:- A combination of a large number of solar cells is term as a Solar cell panel.

7. What are Semiconductors?

Ans:- Semiconductors are the materials which ordinary do not allow electricity to flow through them.

  • It’s mean that it is not good conductor of electricity.

8. What are the application of solar thermal energy?

Ans:- i. Its use in the field of powering earth satellite.

          ii. They also use in the field of solar water heating.

         iii. Its also use in the field of electric power generation.

         iv. Its may use in the field of solar distillation.

         v. They may use in the field of solar domestic cocking.

9. Define Concentrating Collector.

Ans:- It is a device to collect solar energy with the high intensity of solar radiation on the absorbing surface with the help of reflector or refractor.

External link

 

Networking

  • Networking is referred as connecting computers electronically for the purpose of sharing information such as files, applications, etc.
  • Basically, network consists of hardware component like computer, hubs, switches, routers and other devices which form the network infrastructure.

Networking || Definition, Types, Advantages, Disadvantages & Applications

  • These are the devices that play an important role in data transfer from one place to another using different technology like radio waves and wires.
  • A network may be linked through cables, telephone lines, radio, satellites, or infrared light beams.
  • It interact with others to exchange information and develop professional or social contacts. 

Definition of Networking

  • A network consists of two or more computer that are linked in order to share resources, exchange files, or allow electronic communication.

or

  • Network means connect the people across the globe and share their idea’s and thought’s.

Components of Networking

  • Following are the components of Network :-

1. Network Card

2. Networking Cable

3. Hubs and Switches

4. Modem

1. Network Card

  • A network card is used to physically attach a computer to a network, so that can participate in network communication.
  • In network card Ethernet Network Card is the most commonly used.

2. Networking Cable

  • A Networking cables are networking hardware’s use to connect one network to other network devices and to connect two or more computers to share scanners, printers etc.

3. Hubs and Switches

  • Hub is a networking device that allows one to connect multiple computers to a single network.
  • They may be based on Ethernet, Firewire, or USB connections.
  • switch is a control unit which turns the flow of electricity on or off in a circuit.
  • They may also be use to route information patterns in streaming electronic data sent over networks.
  • A Hub/Switch performs the following functions :-
  • Acts as a central points of connection for all the computers on a network. Every computer plugs into the hub/switch.
  • To arrange the points in such a way, so that if a PC transmits data, the data is sent over the other computer through its network card.
  • Basically, the hub/switch is a box with a set of RJ-45 ports. Each computer on a network is connect to the hub/switch via Ethernet cable.

4. Modem

  • A modem enables you to connect your PC to the available internet connection over the existing telephone lines.
  • It converts the digital signals of a PC into analog signals to enable their transmission via phone lines.

Types of Networks

  • There are various types of networks which are as follows :-

1. Personal Area Network ( PAN)

2. Local Area Network ( LAN )

3. Metropolitan Area Network ( MAN )

4. Wide Area Network ( WAN )

1. Personal Area Network ( PAN)

Networking || Definition, Types, Advantages, Disadvantages & Applications

Image: PAN

  • PAN is a PC network that’s mainly created for an individual person.
  • This is used for communication among devices, like laptops, mobile phones, PDA or smartphones.
  • PAN generally covers a range of less than 10 meters ( about 30 feet ).
  • They may be wired or wireless.

2. Local Area Network ( LAN )

Networking || Definition, Types, Advantages, Disadvantages & Applications

Image: LAN

  • In LAN, two or more computers and peripheral devices are connected within a small area, like room, office building or a campus.
  • In Local Area Network, computer terminals are physically connected with wires.
  • The data transmission speed is slow as compared to Wide Area Network.
  • Since LAN is operated in a small area, it can be controlled and administered by a single person or an organisation.

3. Metropolitan Area Network ( MAN )

Networking || Definition, Types, Advantages, Disadvantages & Applications

Image: MAN

  • MAN is large network than LAN.
  • It spreads across a city.
  • Since it covers a city, which is called metropolitan.
  • The most common example of Metropolitan Area Network type network is the cable television, branches of a local bank in a city, etc.

4. Wide Area Network ( WAN )

Networking || Definition, Types, Advantages, Disadvantages & Applications

Image: WAN

  • In WAN network connects two or more computers located at distant places.
  • They link to communicate facilities, like telecommunication or satellite signals for example telecom system, ATM facility, etc.
  • The main characteristic of Wide Area Network is that it requires a public telecommunication media to transfer data.

Networking Architecture

  • Network architecture is overall design of a computer network that describes how a computer network is configured and what strategies are being used.
  • Network architecture mainly are of two types, which are as follows :-

1. Client- Server Network

2. Peer to Peer Network

1. Client- Server Network

Networking || Definition, Types, Advantages, Disadvantages & Applications

Image: Client- Server Network

  • This is a network, where several computers called Clients or workstations are connected to the main computer called the server.
  • A Server is a computer which provides services to clients and controls access to hardware, software, and other resources.
  • Clients are the computers, that request services, like data retrieval, storage, etc., from the server.

2. Peer to Peer Network

Network Networking || Definition, Types, Advantages, Disadvantages & Applications

Image: Peer to Peer Network

  • This is a network where a few computers having equal capacity and capabilities are connected together to use the resources available on the network.
  • In this network, there is no central server instead each computer can act as a server as well as a client.

Network Topologies

  • Network Topology refers to the layout in which various components of a network, like nodes, links, peripherals, etc, are connected and communicate with each other.
  • Topology can be either physical or logical.
  • Physical Topology is the physical format of nodes, workstations and cables in the network.
  • Whereas Logical topology is the way information flows between different components.
  • Network Topologies are classify into the following basic types :-

1. Point- to- Point

2. Bus Topology

3. Star Topology

4. Ring Topology

5. Tree Topology

6. Mesh Topology

1. Point- to- Point

Networking || Definition, Types, Advantages, Disadvantages & Applications

  • This is the simplest form of network structure in which two nodes are directly connected to each other.
  • This type of network is more suitable for small areas where computers are in close proximity.
  • This technology provides a faster and reliable connection.

2. Bus Topology

Networking || Definition, Types, Advantages, Disadvantages & Applications

  • This topology uses a single communication line or one main cable to which all nodes are directly connected.
  • The main cable acts as a backbone for the networks.
  • In this type of structure one of the computers in the network acts as the computer server, that provides data to all the clients.
  • This topology uses in small networks where cable requirement is relatively small.

Di advantages

  • If the main cable fails, the entire network becomes unusable.
  • For this reason, this type of topology is not using for large networks.

3. Star Topology

Star_Topology

  • In this topology, each device connects to a central computer using a point- to- point connection. The Central server acts as a Hub.
  • This is very popular because the startup cost is low.

Advantages

  • If any one connection in the network fails, the other connections remain intact.

Di advantages

  • If the central hub fails, the entire networks go down.

4. Ring Topology

Ring_Topology

  • In this topology, all the nodes in the network connects in a circular manner.
  • Each nodes connect to exactly two other nodes, forming a single continuous pathway for signals.
  • Both LAN & WAN setups are use in Ring topology.

Di advantages

  • If one workstation goes down, the entire networks got affect.

5. Tree Topology

Tree_Topology

  • This is one of the most common network setups that consists of a group of star- figured workstations connected to a linear bus backbone cable.
  • In this topology, one star network connects to the other star networks.
  • In a tree network, a cable failure in one of the star network will isolate only the workstation that links to the central computer of that star network.
  • Whereas, all the other workstations will continue to function normally.
  • If central computer goes down, the entire workstations connect to it will suffer either degrade performance or complete failure, but rest of the network will continue to function normally.
  • In the Tree topology, expansion of network is possible and easy but maintenance becomes difficult.

6. Mesh Topology

Mesh_Topology

  • In this topology, each node connects to every other node in the network.
  • In Mesh topology, every node not only sends its own signals but also relays data from other nodes.
  • This type of topology can handle a large volume of traffic.
  • In case, if one of the component fails, there is always an alternative present so that the data transfer doesn’t get affected.
  • Even expansion and modifications can be done in this topology without affecting other nodes.
  • Overall cost of this network is extremely high as compared to other network topologies.

Networking Security

  • Network Security means protecting data and resources from any unauthorised access.
  • It is the most important aspect in computer networking.
  • These are the following points that may happen in any organisation :-
  • Some employees may try to change the data concerning their leave records, salaries, performance appraisals, etc.
  • Accidental deletion of important data.
  • Former employees or some other people may try to harm the company’s data.
  • People outside the company can try to access confidential data.
  • There are Two general levels of network security :-

1. Login security

2. Right security

1. Login security

  • You give a unique login name and password.

2. Right security

  • Based upon your user name, you give rights, like Read- Only Access or Read- Write Access at all.
  • A combination of rights may also be granted to the same user for different sets of data.

Advantages of Networking

  • For efficient use of storage media.
  • For preserving information.
  • To reduction in hardware costs.
  • Efficiency
  • For redundancy
  • Quickest document delivery

Dis advantages of Networking

  • A PC on a network is vulnerable to hackers.
  • There is a chance of hacking, particularly with wide area networks.
  • Viruses can spread to other computers throughout a PC network.
  • If the file server breaks down the files on the file server become difficult to reach.

Applications of Networking

  • For sharing.
  • Printer sharing.
  • To Communication and collaboration.
  • To remote access.
  • For data protection.

About related to machine click on the link

Lathe machine

Capstan Lathe

Heat Transfer

 

Let’s Know More

  • Conferencing
  • When two users have simultaneous conversation via internet, it’s call Conferencing.
  • Video Conferencing
  • In Video Conference participants in different locations are able to communicate with each other in sound and vision.
  • Bluetooth
  • It is a wireless technology use for interconnect mobile phones, computers, printers using short- range of wireless connection.
  • Protocols
  • Protocols are the certain sets of rules that determine how data should be transfer over the screen and so on.
  • Wireless
  • It means of communication that uses low power ratio between devices.
  • Wi-fi
  • Wi-fi stands for Wireless Fidelity.
  • It represents wireless local area network.
  • WAP
  • WAP stands for wireless access point.
  • This is a device that connects wireless communication devices to form a wireless network.

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INTRODUCTION:

In the Mechanical Engineering field Lathe plays an important role in Manufacturing. In this article, I am going to discuss the Lathe machine in detail.

  • Lathe machine refers to a machine tool which used to remove unwanted metals from the work piece to give desired shape and size.
  • Lathe machine is one of the most important machine tools which is used in the metalworking industry.
  • It operates on the principle of a rotating work piece and a fixed cutting tool.
  • The cutting tool is feed into the work piece which rotates about its own axis causing the workpiece to form the desired shape.
  • It is also known as ” the mother/father of the entire tool family”.
  • It was invented by  DAVID WILKINSON ( 05 Jan. 1771 – 03 Feb. 1852).

Main Parts of Lathe MachineDefinition of Lathe Machine

  • The machine tool that ‘s used to remove unwanted metals from the work piece to give the desired shape and size so called ” Lathe machine “.
  •  Lathe machine is also known as “ Center Lathe ” because of two centers between which the job can be held and rotated.

Functions of lathe Machine

  • The main function of Lathe is to remove excess material in the form of chips by rotating the work piece against a stationary cutting tool.
  • This is accomplished by holding the work securely and rigidly on the machine and then turning it against cutting tool which will remove metal from the work.
  • To cut the material properly the tool should be harder than the material of the work piece, should be rigidly held on the machine and should be fed or progress in a definite way relative to the work.

Main Parts of lathe Machine

  • In a lathe machine every individual part performs an important task.
  • Some important parts of a lathe machine are as follows:

Line diagram of main parts of lathe machine

Line Diagram: Main Parts of Lathe Machine

1. Bed

2. Head Stock

3. Main Spindle

4. Tail Stock

5. Lead Screw

6. Live Center

7. Dead Center

8. Carriage

   i. Saddle

  ii. Apron

  iii. Tool Post         

  iv. Cross slide

  v. Compound Rest

  vi. Compound Slide

9. Feed Mechanism

 i. Belt Feed Mechanism

 ii. Gear Feed Mechanism

 

1. Bed

  • The Bed forms the base of a machine.
  • It is mounted on the legs of the lathe machine, which are bolted to the floor.
  • It is made up of cast iron and its top surface is machined accurately and precisely.

2. Head Stock

  • Head stock is an important part of a lathe machine, which is mounted permanently on the inner guide – ways at the left hand side of the bed.
  • It consists of a main spindle, a chuck fitted at spindle nose, back gear drive and all gear drive.

3. Main Spindle

  • A main spindle is a hollow cylindrical shaft.
  • It’s face has a standard moarse taper.
  • It is used for holding the live centre or collet.
  • The spindle rotates on two large bearings housed on the head stock casting.
  • The front end of the spindle is threaded, those are used for holding the chuck, face plate, driving plate and catch plate.
  • It is know as a spindle nose.

4. Tail Stock

  • A tail stock is located on the inner guide – ways at the right side of the bed opposite to the head stock.
  • The body of the tail stock is bored and house the tail stock spindle.
  • The spindle moves front and back inside the hole.
  • It has a taper hole to receive the dead centre or shunk of tools such as drill or reamer.
  • It’s body made up of cast iron.

5. Lead Screw

  • It is used to transmit power to carriage through gear and clutch arrangement in the carriage apron.

6. Live Center

  • A Live Center is mounting on bearings and rotates with the work.
  • Live centers are using to hold or support a work-piece.

7. Dead Center

  • A dead center may be use to support the work piece at either the fixed or rotating end of the machine.
  • Dead centers are typically fully harden to prevent damage to the important mating surfaces of the taper and to preserve the 60° angle of the nose.

8. Carriage

  • A carriage is located between the head stock and tail stock on the lathe bed guide – ways.
  • It can be moved along the bed either towards or away from the head stock.
  • It has several parts to support, move and control the cutting tool.

Carriage

Image: Carriage

i. Saddle

  • It is H – shaped casting.
  • The saddle connects the pair of bed guide – ways as a bridge.

Saddle

 

  • It fits over the bed and slides along the bed between head stock and tail stock.
  • The saddle can be moved by providing hand feed or automatic feed.

ii. Apron

  • The front portion of a carriage call as apron. It consists of all control keys.

Apron

 

  • The handle operates the carriage. It has a housing, which has a set of gears and split nut.
  • Automatic feed and threading control are on the apron.

iii. Tool Post

  • It is located on the top of the compound slide. It is used to hold the tools rigidly.
  • Tools are selected according to the type of operation and mounted on the tool post and adjusted to a convenient working position.
  • There are different types of tool post, which are as follows.

a. Single Way / Screw Tool Post

b. Four Way Tool Post

c. Quick Change Tool Post

d. British Type Tool Post

iv. Cross slide

  • It is situated on the saddle and slides on the dovetail guide – ways at right angles to the bed guide – ways.

Cross_Slide

 

  • It carries compound rest, compound slide and tool post.
  • Cross slide hand wheel is rotated to move it at right angle to the lathe machine axis.
  • The cross slide hand wheel is graduate on its rim to enable to give known amount of feed as accurate as 0.05 mm.

v. Compound Rest 

  • It is a part which connects to cross slide and compound slide.
  • It is mounted on the cross slide by tongue and groove joint.

Compound_Rest

 

  • The compound rest can be swiveled to the required angle while turning tapers.
  • A top slide known as compound slide is attached to the compound rest by dovetail joint.

vi. Compound Slide 

  • Compound slide is a T -shaped rounded slot, which is fixed with cross slide upper surface by two bolts, which is related to a micrometer sleeve and screw handle with the outer edge of screw.
  • Taper turning can be possible by setting the compound slide at half of a required angle.
  • This slide is only used for less long job taper turning.
  • The automatic feed is not possible in compound slide. 

9. Feed Mechanism

  • There are several mechanisms to make the carriage and cross slide move automatically to change the direction of their movement.
  • Some important feed mechanisms are as follows:

i. Belt Feed Mechanism

Belt_Feed_Mechanism

 

  • Belt feed mechanism is widely use in oldest lathe machines.
  • In this, a cone stepped pulley is used for providing the different types of speed.
  • To change the speed, a lever is used for sliding the belt at one pulley to another.
  • Belt feed mechanism has a disadvantage of the belt slipping in pulley changing process.

ii. Gear Feed Mechanism

Gear_feed_mechanism

 

  • In the gear feed mechanism, the power is transmitted from spindle to feed rod or lead screw by power gear train.
  • Gear 1 is situated at the back side of the spindle and the tumbler bracket consists of the gears 2, 3, 4 and 5.
  • A lever operate the bracket. This bracket is pivoted about the axis of the stud gear.
  • This position of the bracket can be arrange in three different stages namely:

a. Neutral Position

b. Forward Position

c. Reverse Position

Working Principle of lathe machine

 Principle

  • A lathe is a machine tool which use to removes unwanted materials from a work piece in the form of chips with the help of a tool that travels across the work piece and can be fed deep in work.

Principle Diagram of Lathe machine

 

  • When the tool is moved parallel to the work-piece then the cylindrical surface is formed.

Working Principle 1

 

  • If the tool is moved inclined to the axis then it produces a tapered surface and so calls as taper turning.

Working Principle of Lathe 2

Working

  • It holds the work between two supports so call as centers.
  • Face plate or Chuck are using for holding the work.
  • Face plate or Chuck are mounted on the machine spindle.
  • The cutting tool is holding with the help of Tool post.
  • The movement of the job is rotating about the spindle axis.
  • Against the revolving work, the tool is feed.
  • The tool  moves either parallel or inclination to the work axis.

Operations of Lathe Machine

Operation of Lathe machine

  Image : Operation of Lathe Machine

1. Turning

 i. Tapers and Taper Turning

 ii. Straight turning

 iii. Profiling

 iv. External grooving, etc

2. Facing

3. Drilling

4. Boring

  i. Counter Boring

  ii. Taper Boring

5. Reaming

6. Knurling

7. Chamfering

8. Filling

9. Parting

10. Threading

11. Grooving

12. Forming

13. Polishing

 

1. Turning

Turning Operation

  • Turning is the operation of reducing the diameter of a work piece to produce a cone -shaped or a cylindrical surface as shown in fig. above.
  • A simple single point cutting tools are use for turning operations.
  • Turning can be different types like

      i. Tapers and Taper Turning

      ii. Straight turning

      iii. Profiling

      iv. External grooving, etc 

i. Tapers and Taper Turning 

  • A taper may be define as a uniform increase or decrease in diameter of a piece of work measured along its length.
  • In a lathe, taper turning means to produce a conical surface by gradual reduction in diameter from a cylindrical work piece.

ii. Straight turning

  • The Straight turning produces a cylindrical surface by removing excess metal from the work piece.

iii. Profiling

  •  In profiling, the cut can be vary with regard to cutting depth, feed and speed.

iv. External grooving

  • In external turning operations machines the outer diameter of the work piece.   
2. Facing

Facing

  • Facing is an operation of reducing the length of a work piece to produce a flat surface square with the axis.
  • A regular turning tool may also be using for facing a large work piece.
3. Drilling

Drilling

 

  • Drilling is an operation of producing a cylindrical hole in a work piece by the rotating cutting edge of a cutter known as the drill.
4. Boring

Boring

 

  • Boring is the operation of enlarge a hole or cylindrical cavity to produce circular internal grooves.
  • Holes may be bore straight and tapered.

i. Counter Boring

  • Counter Boring is the operation of enlarging a hole through a certain distance from one end instead of enlarging the whole drilled surface.

ii. Taper Boring

  • Taper Boring is similar to the external taper turning operation and is accomplished by rotating the work on chuck or a face plate, and feeding the tool at an angle to the axis of rotation of the work piece.
5. Reaming

Reaming Operation

  • Reaming is the operation of finishing and sizing a hole which has been previously drilled or bored.
  • The tool use so call as the reamer, which has multiple cutting edges.
6. Knurling

Knurling

 

  • Knurling is the process of embossing a diamond shaped pattern on the surface of a work piece.
  • The purpose of knurling is to provide an effective gripping surface on a work piece to prevent it from slipping when operated by hand.
7. Chamfering

Chamfering

 

  • Chamfering is the operation of beveling the extreme end of a work piece.
  • This is done to remove the burrs, to protect the end of the work piece from being damaged and to have a better look.
8. Filling
  • Filling is the finishing operation performed after turning.
  • This is done in a lathe to remove burrs, sharp corners, and feed marks on a work piece and also to bring it to the size by removing very small amount of metal.
  • The operation consists of passing a flat single cut file over the work piece which revolves at high speed.
9. Parting

Parting

  • Parting is the operation of cutting a work piece after it has been machining to the desired size and shape.
  • This process involves rotating the work piece on a chuck or face plate at half the speed that of turning and feeding by a narrow parting – off tool perpendicular to the axis by rotating the cross -slide screw by hand.
10. Threading

Threading

 

  • Threading is a operations to produce a helical groove on a cylindrical or conical surface by feeding the tool longitudinally when the job is revolved between centres or by a chuck.
  • Threads can be produced either on internal or external surface of a cylindrical bar.
11. Grooving
  • Grooving is the process of reducing the diameter of a work piece over a very narrow surface.
  • It is often done at the end of a thread or adjacent to a shoulder to leave a small margin.
  • Grooving Operations are:

Grooving_Operation

 

      a. Square Groove

      b. Round Groove

      c. Bevelled Groove

12. Forming

Forming

 

  • Forming is the process of turning a convex, concave or of any irregular shape.
13. Polishing
  • It is basically a surface finishing operation to improve the surface quality of the work piece.
  • Polishing with successively finer grades of emery cloth after filling results in very smooth, bright surface.

Types of lathe machine

    Lathe machines are classified according to their construction and design. Some of them are:

1. Bench lathe

2. Speed lathe

3. Engine lathe or center lathe

4. Tool room lathe

5. Capstan and turret lathe

6. Special purpose lathe

7. Automatic lathe

  1. Bench lathe

  • Bench lathe is a small lathe usually mounted on a bench.
  • This is using for small and precision work.

   2. Speed lathe

  • Speed lathe is the simplest of all types of lathe in construction and operation.
  • It consists of a bed , a head stock, a tail stock and a tool – post mounted on an adjustable slide.
  • The spindle speed is about 4000 rpm.
  • They  named  because of very High Speed of head stock spindle.

   3. Engine lathe ( center lathe )

  • The term ” engine ” is associated with the lathe which is early driven by steam engines.
  • An engine lathe is also know as a reproductive machine because of its production capabilities.
  • Engine lathes are an excellent tool, which aids in the creation of many modern tools.

Advantages

  • It is using for mass production of products.
  • It is using for manufacturing cylindrical shapes like steels and plastics.

Disadvantages 

  •  It is very difficult to program in machine language.
  • corruption, poor service, and racial issues.

 

  4. Tool room LATHE

  • Tool room lathe is similar to an engine lathe.
  • This lathe is mainly using for precision work on tools, Dies, Gauges and in macing work where accuracy is necessary.
  • It is used for making precision components in the tool room.

5. Capstan and turret lathe https://mechanicalnotes.com/capstan-and-turret-lathe-introduction-working-advantage-difference/

  a. Capstan Lathe

Capstan Lathe Machine

 

  • They having features of the basic lathe and have short slide tail stock.
  • A Capstan machine is a processing machine uses for making the same parts again and again.

Advantages

  • The production rate is high.

Disadvantages

  • The heavier work-piece cannot machine by  capstan lathe.

b. Turret Lathe

  • The turret lathe is a form of metalworking lathe.
  • It is used for repetitive production of duplicate parts.
  • In a turret lathe, a longitudinally feed able, hexagon turret replaces the tail stock.

Advantages

  • Turret lathe is using to machine the long and heavy workpieces.
  • They having hexagonal tool post or head.
  • There is no need of changing  the tool.

Disadvantages

  • They have manual indexes.

6. Special purpose lathe

  • Special Purpose lathe are using for special purposes and for jobs which cannot be accommodated or conveniently machined on a standard lathe.

  7. Automatic lathe

  • In the automatic lathe, the various operations are automating like the change of the work piece.
  • The working cycle is fully automatic that is repeated to produce duplicate parts without participation of operator.

Advantages 

  • During machine operation operator is free to operate another machine.
  • More economy in floor space.

Disadvantages

  • Lots of consideration are taking on fixing the setup.

Lathe Accessories 

  • Lathe accessories are generally dividing into two categories :-

1.Work Holding device and 

2. Cutting Tool Holding device

   1. Work Holding device 

  • The work holding devices are the device that is using to hold and rotate the work pieces along with the spindle.
  •  The different work holding devices are using, according to the shape, length, diameter and weight of the work piece and the location of turning on the work. They are as follows :-

A. Chucks

  • A chuck is a specialized types of clamp used to hold the work piece.
  • Chuck is mounted on the spindle which rotates within the head stock.

Three Jaw Chuck

  Types of chucks :

  1.  Three Jaw Chuck
  2.  Four  Jaw chuck
  3.  Collect Chuck
  4.  Spindle Chuck
  5.  Magnetic Chuck
  6.  Combination Chuck
  7.  Air Operated Chuck

B. Face Plate

Face Plate

 

  • Face plate is a circular disc and thread to fit to the nose of the lathe spindle.
  • They having radial plain and ‘T’ – slots for holding the work by bolts and clamps.

C. Mandrels

Mandrel

  • Mandrel is a device which uses for holding a hollow work piece.
  • Mandrel is mounting between centers and work revolves with it .

D. Centers

Live Center

 

  • A lathe center is a tool that has ground to a point to accurately position a work piece.
  • There are two centers :-

    a. Live center

  • A live center is a center which fits into the head stock spindle and revolves with the work.
  • A live center is constructed so that the 60 degree center runs in its own bearing.

      b. Dead center

  • Dead center is the center which uses a tail stock spindle and doesn’t revolve.

     c. Half center

  •  Half center is the center which is often used in the tail stock  for facing up to or for Turning close to the end of the work .
  •  It cuts away almost to its point .

 E. Driving Plate or Catch Plate

Driving Plate

 

  • Catch plate is plane disc which is made up of cast iron or steel.
  • They having a central

F. Carriage

Carriage

  • Carriage is a device that Clamps around the work piece .
  • They allow the rotary motion of the machines spindle to transmit  the work piece.
  • There are two types of carriage :-

a. Straight Tail Carriage

  • This is using for driven the work by means of the pin provided in the driving plate .

b. Bent Tail Carriage

  • It fits into the slot of the catch plate to drive the work .

c. Angle Vise

Angle Vise lathe machine

  • Angle vise is an angular adjustment on base to allow operator to drill holes at an angle without tilting table .

2. Cutting Tool Holding device

  • The cutting tool holding device is a device which is using to hold the cutting tools .
  • The different cutting tool holding devices are as follows:-

A. Tool Post

Tool Post lathe machine

  • Tool Post is a device which holds the cutting tool on a lathe and some other machine.

B. Collect

Collect

  • Collect is a device which is using to hold a cutting tool in the spindle of a milling machine.

C.  Drill Chucks

Drill Chuck lathe machine

  • It is the most common devices which are using for holding straight-shank cutting tools.
  • There are two common types:-

a.  Key Type

  • It has loosened or tightened by key.

b.  Keys Less Types

  • It has loosened or tightened by hand without the key.

D. Drill Sleeves

Drill Sleeve lathe machine

  • Drill sleeves are used to adapt smaller Morse taper shank tools to larger machine spindles.

E.  Drill Socket

Drill Socket lathe machine

 

  • Drill socket is used to hold twist drills with shanks.
  • They have used often an extension socket.

F. Straight Tool Holders

Straight Tool Holder lathe machine

  • Straight is using for taken cuts in either direction and for general machining operations.

Specifications of Lathe Machine:

 1. a. Center distance

      b. Height of center

      c. Type of bed

2. a. Swing in gap

      b. Gap in front of face place

      c. Swing over cross slide

      d. Swing over bed

3. a. Spindle bore

      b. Spindle speed range

      c. Spindle nose

      d.Taper nose

4. a. Longitudinal feeds

      b. Cross  feed

      c. Lead screw pitch

      d. Metric thread pitches

5. a. Top slide travel

      b. Cross slide travel

      c. Tool section

6.  a. Taper in sleeve bore

      b. Tail stock  sleeve travel

7.  Motor horsepower in RPM ( Revolution per minute ).

8.  Shipping dimension 

Some keys points

1. Feed

  • The rate at which the cutting tool crosses the work piece in the direction perpendicular to the work piece axis so calls as feed.

2. Depth of cut

  • It is the perpendicular distance measured from the machined surface to the UN – cut surface of the work piece.

3. Cutting Speed

  • The speed at which the metal is removing from the work piece with the help of tool so call as cutting speed.

 Formula

Cutting Speed = πdn / 1000 

4. Grinding

  • Grinding is the operation of removing metal in the form of minute chips by feeding the work against a rotating abrasive wheel so call as Grinding wheel.

Heat Transfer

  • The term heat is taken as synonymous to warm vitality.
  • This utilization has its birthplace in the recorded understanding of warmth as a liquid ( caloric ) that can be moved by different causes, and that is additionally regular in the language of laymen and regular daily existence.
  • Heat transfer consistently moves  from a region of high temperature to another region of lower temperature.
  • It changes the inside vitality of the two frameworks required by the principal law of thermodynamics.
  • The trading of dynamic vitality of particles through the limit between two frameworks which are at various temperatures from one another or from their environment.
  • The second law of thermodynamics characterizes the idea of thermodynamic entropy, by quantifiable warmth move.
  • Thermal equilibrium is reached when all involves bodies and the surroundings reach the same temperature.

Definition of Heat Transfer

  • It is defined as the transmission of energy from one region to another region to temperature difference.

or

  • The flow of heat from one body to another or from one part of the body to another is called Transfer of Heat.

Also Read by touching the link:

Heat Treatment: Definition in Details.

Fluid: Definitions in Details

Methods of Heat Transfer

  • There are three methods of heat transfer namely :-

1. Conduction

2. Convection

3. Radiation

Heat Transfer || Definition, Modes, Conduction, Convection & Radiation

1. Conduction

  • Conduction is the flow of heat in a substance due to the exchange of energy between molecules having more energy and less energy.
  • In Conduction, energy exchange takes place by the kinematics motion or direct impact of molecules.
  • Pure conduction is found only in solids.

Conduction_in_Solids

Mechanism 

  • Lattic vibration ( 70 % ).
  • Due to the free electron ( 30 % ).

Fourier’s Law of Heat Conduction

  • It states that the rate of heat conduction through plain layer to the solid body is proportion to the temperature difference across the layer & heat transfer area inversely proportional to the thickness of layer. 

             Q = – KA × ( dt / dx )

            K = Thermal conductivity

        A = Area Square meter

      ( dt / dx ) = Temperature Gradient

Thermal conductivity

  • Thermal conductivity is the ability of the material to conduct heat.
  • Its unit is W / m K or °C.

Representative values of some thermal conductivity material

  • For Solid
Metal K ( W / m K ) State
Siliver 429 20°C
Copper 401 20°C
Pure Cu 380 20°C
Brass 110 20°C
Steel 54 20°C
Stainless Steel 16 20°C
Non-metal
Asbestos 0.23 20°C
Plastic 0.58 20°C
Wood 0.17 20°C
  • For Liquid
Liquid K ( W / m K ) State
Water 0.60 20°C
Light Oil 0.14 20°C
  • For Gases
Gases K ( W / m K ) State
Dry air 0.026 20°C
Steam 0.025 20°C

 

2. Convection

  • The transfer of energy from one region to another due to the macroscopic bulk motion in a fluid, aeeded onto the energy transfer by conduction is called heat transfer by convection.
  • It is possible only in the pressure of fluid medium.

Convection_in_Liquid

  • Liquids and gases are mainly heated by convection as they are insulators of heat.
  • Solids cannot be heated by convection as their particles are very tightly packed. Hence, they are unable to move.
  • For examples, when you light a candle, the air above it gets heated and moves upwards.
  • Similarly, we can see smoke from burning objects like incense stick, paper, etc move up. The particles are heated and moves upwards.

Characteristics of Convection

  • For heating using the convection process, a material medium is necessary.
  • It is not necessary that the particles of the medium should be compact.
  • That is why liquids and gases can transmit heat through convection, but not solid.
  • For transmission of heat through convection, actual movement of particles of that medium is essential.

Applications of Convection

  • It causes land and sea breeze in coastal areas.
  • In coastal areas, breeze blows from the sea towards the land during the day. It is called sea breeze.
  • At night, breeze blows from the land towards the sea. It is called land breeze.
  • The reason for this is as follows:-

Heat Transfer || Definition, Methods, Formula & Application

  • During the day, the land surface heats up faster than the sea.
  • Air above the land becomes warm and rises up.
  • The cool air from the sea blows towards the land to take its place. This is called sea breeze.

Land_Breeze_At_Night

  • At night, the land cools much faster than the sea.
  • Thus, the sea is warmer than the land.
  • The air above the sea is warm and rises up.
  • A current of air blows from the colder land to warmer sea to take its place. This is called land breeze. 

Newton’s Law of Cooling or Convection Law

  • It states that the rate of heat flux transfer from surface to fluid is directly proportional to the difference in temperature.

             q = hA ( Ts – T∞ )

Ts = Temperature of fluid

T∞ = Temperature of the surface

3. Radiation

  • The heat transfer from one body to another without any transmitting medium is known as Radiation.
  • It is an electromagnetic wave phenomenon.
  • For examples, we feel warm when we are in the sun, we feel warm when we sit near a fire.
  • Black and dull surfaces absorb more heat radiations as compared to white and shiny surfaces.

Properties of Radiation / Characteristics

  • It doesn’t require any medium.
  • Rate of emission increase with temperature level.
  • It travel with the speed of light.

Applications of Radiation

  • The bottom part of some cooking utensils is painted black so that it can absorb more heat and the food gets cooked rapidly.
  • Room heaters are provided shiny surface reflects and absorbs very little heat.

Fundamental Law of Heat Transfer

  • There are two law of heat transfer :

1. Fundamental law

i. Law of conversation of mass

ii. Newton Law of motion

iii. Law of Thermodynamics

2. Subsidiary law

i. Fourier Law of Heat Conduction

ii. Newton’s Law of Cooling

iv. Law of Radiation

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