Energy

Nothing can move or work without energy. We need energy for our survival. The amount of work we do every day depends on our energy level. We get energy from the food we take. Plants need energy for growth. Engine also needs energy for its functioning. Some engines use electricity and some need fuel for energy. Energy is stored in fuel.

What do we mean by energy? The energy of a body means its ability to work. So the body which is able to work has energy in it and the body that does not have energy in it cannot work.

When we say a body has energy in it we mean the body can apply force on other and can work. Again the amount of work done on a body is equal to the energy we use.

The energy of a body refers to its ability to work. Here work means the transformation of energy from one form to another. It means that the total amount of work that a body can do is its energy. The amount of work a body can do is the measure of its energy. So, the amount of work done is the amount of energy used.

Therefore, Work done = Energy used

Energy has no direction. So it is a scalar quantity.

The unit of energy and work is the same and it is joule (J).

Different forms of energy

We need different type’s energy for doing different kinds of work. For example we need heat to boil water. We get light energy from an electric bulb. There is sound energy in the music we hear. We need muscular energy to shift or to lift any object. Electrical energy is necessary to operate an electrical device. We get chemical energy by chemical reaction in the electric cell. A piece of paper flies due to energy of air. Nuclear energy is released when the atoms are accumulated or broken.

The universe is in motion as there is energy. If no energy existed the universe would be motionless. As there is light energy we can see and hear because of sound energy. We can move for mechanical energy. Fan rotates and factory runs with the help of electric energy. Energy exists in the universe in different forms.

Generally we observe the following forms of energy. Such as, mechanical energy, heat energy, sound energy, light energy, magnetic energy, electrical energy, chemical energy, nuclear energy and solar energy.

Sources of Energy

The modern mechanized civilization cannot proceed a moment without energy. Work is available at the expense of energy. Uninterrupted energy supply is essential for the survival of all living creatures. The demand of energy is increasing day by day with the development of life style. For this increasing demand of energy man is looking for newer sources of energy. We need to have clear idea about the sources of energy to save the living beings and to continue the supply of energy. We know that the sun is the only source of all energy. Moreover, the nuclear energy in the nucleus and the energy from the hot melted substances are considered to be the sources of energy. All the existing energy of the world is directly or indirectly comes from the sun or are produced using the radiation of the sun.

Chemical Energy/Fuel Energy

Man in the ancient time was dependent wholly on the energy of their muscles. Afterwards, they learnt to tame the wild animals and use their energy in different work. They used to carry their goods and cultivate land with the help of animals. The initial stage of civilization was to produce heat energy from burning wood and leaves and mechanical energy from current of water and flow of wind. The economic development of human being begins from the use of machine energy. Industrial revolution and invention of steam engine reduced men’s dependence on muscle energy of human and animals. Man kept operating different machines with the help of steam energy. Fuel is necessary to produce this steam energy. So we consider different kinds of fuels to be the sources of energy.

The most common sources of energy are coal, mineral oil and natural gas. Coal, mineral oil and natural gas from underground are used as fuel directly or by refining them slightly.

Coal

Coal is best known to us as one of the sources of energy. It is an organic substance. Once upon a time there were numerous plants and trees. Due to different natural calamities and natural consequences the leaves of the trees and their stems were buried underneath the earth and began to coagulate. As a result of chemical changes, the leaves of the trees and stems were transformed into coal. Combustion of coal gives us heat directly. This is a well-known fuel. Many essential substances can be produced from coal apart from using it as a fuel. Some of the coal products are coal gas, tar, benzene, ammonia, toluene etc. Coal is used to cook food and to drive the steam engines. In modern age, the main use of coal is in thermal power plants. The main fuel in a thermal power station is coal.

The main problem of a coal fueled power station is that it emits sulphur smog which causes acid rain. Though this acid is very weak, it kills the fishes of pond, cannel and lake, destroys forest and damages the sculptures of stone.

Mineral Oil

Petroleum or mineral oil is one of the principal sources of energy. It is widely used as a fuel in the present world. It is being used right from a rural cottage to the most modern transport system. Petrol, pitch that is used to pave roads, kerosene and chemical fertilizers are all petroleum products. There is nothing like petrol to be used as fuel. On the other hand, many kinds of artificial fabrics can be developed from petroleum. These are terry line, polyester, cashmilon etc. Moreover, various types of cosmetics are produced from petroleum. But it is basically used as a fuel. Petroleum products are used to produce electric and mechanical energy. Petroleum is a Latin word. It is a combination of two minor words: Petro and Olium. In Latin language ‘petro’ means stone and ‘olium’ means oil. So, petroleum means oil of stones i.e. oil stored inside stones. In tertiary age i.e. almost five to six crores of years ago the trees and the animals fell buried in the different layers of sedimentary rock on the bottom of the sea. Due to different chemical changes these were transformed into mineral oil. Most of the solid regions of the present world were a part of the bottom region of the sea in prehistoric age.

Natural Gas

Natural gas is a well-known source of energy. Use of natural gas is very high in all advanced countries. It is also used in different industries as fuel. It is also used in fertilizer factories. Heat energy is produced by the combustion of gas and electric energy is produced from heat energy in a thermal power station.

Natural gas is obtained from underneath the earth. Digging very deep well the gas may be taken out from underneath the earth. Tremendous temperature and pressure inside the earth is the root cause of the creation of the gas. Natural gas is also available in petroleum well. The principal element in a natural gas is the methane gas. These are called fossil energy.

The three sources of energy discussed above are reducing very fast due to the men’s increasing demand of energy. The physical condition of the world is such that these sources-coal, mineral oil, natural gas cannot be recreated, these are called nonrenewable energy. So men are looking for alternate sources of energy of which solar energy, energy from water flow, energy from tide and ebb, geothermal energy, wind energy, biomass etc. are the main sources. These sources are directly or indirectly dependent on the sun. As long as earth receives sunlight the energy supply from these sources is possible. These are called renewable sources.

Solar Energy

The energy that we obtain from the sun is called Solar Energy. It is known to all that the sun is the source of all energy. The origin of all forms of energy is from the solar energy in one way or the other. For an example, the fossil fuel such as coal, mineral, oil, and natural gas is actually a store of solar energy for a long time.

From ancient times man is using sunlight directly to dry things. At present man is adopting various means to use the solar energy round the clock. Ignition can be done by concentrating sun’s rays- with the help of a convex lens. Solar cooker consists of a metallic bowl on which the solar rays are reflected. The cooker can be used in cooking purposes.

Take a concave mirror with a focal length of 15cm or 20cm. Hold the mirror facing the sun. Take a piece of paper and concentrate the sunlight with the help of the mirror on it. Hold the mirror till the paper ignites.

The solar rays are used to keep the dwelling houses warm in cold countries. Solar energy is used for drying purposes of crops, fish, vegetables etc. Dried fish can be preserved for many days. More examples of solar energy are- solar water heater, solar cooker etc.

Solar cell has been made by using modern technology. The characteristics of a solar cell are that the cell produces electricity instantly while solar rays fall upon it. There are various uses of solar cell.

1.       This cell is used to supply electricity in artificial satellites. For this reason the artificial satellites move along their orbits for a long time.

2.       Solar energy is being used to operate different electronic devices like pocket calculator, pocket radio and electronic watch.

3.       Currently electrical energy is produced from solar energy in the rural area, houses or offices to meet up the need of electricity.

The advantage of solar energy is that it does not pollute the environment. There is almost no possibility of danger in using this energy. There is also no possibility of sudden exhaustion of solar energy. This is why it is likely to be used as a prospective fuel instead of fossil fuel.

Hydroelectricity (Transformation of mechanical energy)

Water is one of the renewable sources of energy. Energy can be produced by means of water current and tide and ebb. There are different forms of energy in the water current such as, kinetic and potential energy. Electricity produced by means of water current is known as hydroelectricity. Different countries of the world make use of potential energy for producing electricity in hydroelectric projects. The method of producing hydroelectricity using the water current is simple. The current of water is used to rotate a turbine. A co-ordination of mechanical and magnetic energy is possible from the rotation of turbines.

Electricity produced by mechanical energy created by water current in co-ordination of magnetic energy is called hydroelectricity.

Hydroelectricity

Man is trying to use the energy of tide and ebb of river or ocean for a long time. The operation of different machines using the energy of tide and ebb has been invented a long time ago.

In France electric energy production projects are being successfully implemented using the energy of tide and ebb. Other countries of the world are also trying to set up tidal energy projects to produce electricity.

Wind Energy

Wind flows due to the difference of temperature in the earth surface. Kinetic energy due to the air flow can be transferred into electric energy. The machine that transforms energy is called Windmill. People in the ancient time used to lift water from well, sail ship using the wind blow. Still today people sail in the boat using air energy. Nowadays electric energy is produced using windmill with the help of technology.

Geo Thermal Energy

The heat in the earth can be used as the source of energy. The heat in the deep of earth is so high that it can melt pieces of rocks. This melted rock is called Magma. This Magma sometimes rises up and remains stored just below the surface of the ground due to geological changes. These types of places are known as hot spot. When the water under the ground comes in contact with the hot spot it turns into steam which remains stored in the ground. This steam could be let out passing a pipe through a hole on the hot spot with the help of high pressure. Electricity can be produced rotating a turbine with the help of this steam. There is such kind of power station in New Zealand.

Biomass Energy

A small fraction of solar energy is transformed into chemical energy by the green plants in the process of photosynthesis and remains stored as biomass in different parts of the trees. Biomass refers to all those organic materials that can transform into energy. Man along with other animals takes biomass as food and keeps their activities of life active by transforming biomass into energy. Biomass can be considered as a multiple source of energy. The organic substances that can be used as the source of energy are – plants and trees, dry wood, waste of wood, crops, husk of rice, herbs, waste of birds and animals, garbage etc. Biomass is mainly composed of Carbon and Hydrogen. One of the renewable sources of energy is biomass.

Biogas can be produced easily from biomass. We can use this gas as the alternate to natural gas and use for cooking even for the production of electricity. The production of bio-gas is very simple. If we keep cow dung and water in 1:2 ratios in a closed pot for dumping, bio-gas will be produced. This gas comes out through a tube. This gas is used for cooking. For the cooking and lighting bulbs for a family of 4/5 persons the requirement of gas can be supplied from the cow dung of only 2/3 cows.

Nuclear energy

Electricity can be produced by using the energy produced in nuclear reaction. The nuclear reaction from which the obtained energy is used to produce electricity is called nuclear fission. Here, uranium is made to react with a neutron of particular amount of energy. This reaction takes place in a nuclear reactor.

In nuclear reaction usually matter that is mass is transformed into energy. But in nuclear reaction only a small fraction of energy of the total mass is transformed into energy. If mass is transformed and E amount of energy is obtained, then,

E = mc²

Here m is the mass transformed into energy.

c is the speed of light that is equal to 3 x 10⁸ ms^-1.

From experiment it is known that in a fission reaction, that is, if a neutron of definite energy strikes a uranium nucleus, then almost

200 Mev = 200 x 10⁶ ev = 200 x 10⁶ x 1.6 x 10^-19 J = 3.2 x 10^-11 J energy is released.

Since nuclear fission is a chain reaction, hence in a moment crores of reactions take place and huge amount of energy is released.

Calculate: If a substance of 1kg mass is converted completely into energy, then how many kilowatt energy will be produced? 1 kilowatt-hour (1 kWh) = 3.6 x 10⁶ J

The energy obtained from this reaction can be transferred to another container as the internal energy of carbon dioxide, by pumping continuously at high pressure in a controlled way. This heated gas moves around a special steam boiler and heats the steam inside which can rotate a turbine and produce electricity. The amount of energy obtained from a ton of uranium by a nuclear reaction will be equal to the amount of energy obtained from burning ten lac tons of coal.

But there are some problems of nuclear power plants. The waste of nuclear fuel is extremely radioactive and so it has to be preserved for thousands of years to make it safe. Moreover, in a nuclear reactor high temperature and pressure is produced. So it has to be made of such a material that can tolerate the high temperature and pressure. Any nuclear accident is very dangerous which we can realize from the accidents of Chernobyl in Soviet Union (at present Ukraine) and Fukushima in Japan. In nuclear power production less greenhouse gas is released in the environment.

The Social Effects and Advantages of Renewable Energy

Uses of renewable energy have a far-reaching effect on our social life. In comparison with the demand of our country the storage of coal, petroleum and natural gas is very poor. So, we have to import mineral oil and coal from abroad to meet up the demand of energy by spending a lot of valuable foreign currency. But utilizing the renewable energy sources that we have in our country especially if we can encourage the people to produce and use bio-gas, we will be able to change the infrastructure of rural area. We can focus our attention to electricity production using windmill. If we can make the use of solar energy available through research, we will be able to meet up all our demands of energy from this unlimited source.

The main advantage of using of renewable energy is that there is no possibility of diminishing of energy. Moreover it will be possible to protect our country from environment pollution.

End

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