What is Energy?
The capacity of doing works is called energy. Since, Energy is the capacity for doing work. Therefore, joule, erg and it poundal are also unit of energy.
In addition to the above units of energy, Kilowatt hours (used for electrical energy) and electron volt (usually used in atomic physics) are also unit o energy.
Energy is constant in the Universe. It can simply be transformed from one form to another.
1 ev = 1.6 x 10^-19 Joules
Sources of Energy —
There are two important sources of energy. They are
- Conventional and
- Non-Conventional sources of energy
Conventional Sources of Energy : The sources of energy which will end in future are called conventional sources of energy.
e.g. Coal, Fire wood, cow dung, waste materials, petroleum, oil and gas etc.
Energy can also be produced by burning purified food grains, skin of such plants as sugar are and vegetables such as potato and other decomposed vegetation.
Non-Conventional Sources of Energy : The sources of energy which will not end ever are called non-conventional sources of energy.
e.g. atomic energy, solar energy, wind energy, bio-gas, hydro-electric power etc.
Importance of Energy —
Energy plays an important role in the production of everything made by man and nature.
Man has used the energy present in its own body and in the bodies of the pet animals and from external resources, in making buildings, roads, bridges, factories, furniture, etc.
The origin of man in nature, their sustenance and reproduction etc. depend on energy.
For the working of machines, fuels such as coal, petroleum and natural gas are needed which undergo combustion with the release of energy.
The energy released keeps the machines working. More is the energy released, better is the fuel.
Human body also requires some energy to keep it running or working. Food serves as sources of energy to the body. This is why food is regarded as fuel for the body.
Energy is required for doing anything. Green plants need the solar energy to prepare its food.
Every creature depends for its nourishment and energy on the food prepared by the plants which contain static energy.
Thus, The existence of every species depends on the solar energy. Therefore, for the existence of every creatures, objects and energy both are required.
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