Solar energy
Light energy and heat energy from the sun are known as solar energy.
Sun has been radiating energy from the past 5 billion years and will continue to do so at the same rate for another 5 billion years or more.
We must find ways to harness the energy with maximum efficiency, although only a small fraction of the solar energy reaches the earth’s surface
Solar cooker
Solar cookers and water heaters use solar energy to operate.
Black surfaces absorb more energy than other surfaces and solar cookers use this property by coating their insides black.
They use reflecting surfaces like mirrors to focus the sun’s rays.
The device is covered with a glass plate thereby establishing the greenhouse effect by trapping heat inside the cooker.
Solar cell
A device that converts solar energy into electricity is known as a solar cell.
A typical solar cell produces a voltage of 0.5 1 V and 0.7 W of electrical power. A large number of such cells can combine to form a solar panel which can generate power large enough for practical uses.
Advantages:
(i) no moving parts
(ii) require little maintenance
(iii) can be set up in remote areas
without the hassle and expenses of transmission lines.
Disadvantages:
(i) Requires a special grade silicon which is not easily available
(ii) Usage of silver for interconnections makes it expensive.
Uses: traffic signals, calculators, artificial satellites and space probes.
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