Sun is universal source of all types of energy and has enormous amount of energy in it. It gives energy in the form of electromagnetic radiations continuously. But few portion of these radiation can pass through the atmospheric layer of earth and reach on earth. This small extent of energy leads to a huge role in everyday life. India receives energy from the sun is approximately 5 × 1015watt. The power of radiations which falls on area of 1 m2is up to 7 kilowatt. This energy is in large amount. If we do not use this energy then it will be wasted.Thissolar energy has some properties.
- Sun gives us energy in the form of electromagnetic radiations.
- It is free of cost, we do not pay for it.
- There are different radiationsof different wavelengths which forms the electromagnetic spectrum.
- The energy emitting from sun never ending.
If we will use non-renewable energy sources continuously then that sources might be lost. So we have to use the solar energy. We do not use this energy directly so we make some devices which convert this energy in usable form. These devices are
- Solar cooker.
- Solar cell
LPG gas is widely used for household purpose. we discussed about conventional energy sources, these sources are limited in nature.Therefore solar cooker is a supplementary for saving LPG gas.To understand the working of solar cell we perform a small activity.
- Take two identical glasses.
- Paint the first glass by white and second by black.
- Fill water in both glasses at equal level.
- Put them in sunlight for an hour.
- After 1 hour touch the glasses one by one.
Which glass is overheated? Definitely black glass is overheated.Why did this happen? Black colour absorbs all the frequencies of Sunlight and energy is depend on frequency of light. Due to this black glass overheated. White glass reflect all frequencies of light so it absorb comparatively minimum energy from sunlight. (Note that perfectly black body absorb all the energy but perfectly black body does not exit.) Therefore white glass does not heat up like black glass. The working mechanism of solar cooker is similar to above activity. The solar cooker is painted black inside it to absorb maximum energy. We can also use convex lens in solar cooker.As we know that convex lens is converging lens.It converges sunlight and focus it on the surface of solar cooker therefore it absorb more sunlight. Construction of school our cooker is as
Light energy can be convert into electrical energy, this phenomenon is explained by famous physicist named Albert Einstein. He performed an experiment named photoelectric effect and explain that light can be convertinto electrical energy. solar cell is based on this principle. As we know that energy is most important for human. The source of energy is power station which it is based on fossil fuel. Transporting cost and power loss of electric current is also higher. Due to this, there are so many villages in which electricity does not reach till. We can solve this problem with the help of solar cell. Single solar cell can produce voltage nearly about 1 volt and we get power upto 0.7 watt from this voltage.The combination of such cell are form solar cell panel. This solar cell panel produces sufficient energy to use. This solar panel are fixed on ground or open space where sufficient sunlight will expose on it. We can fix it on terrace of building. A semiconducting material silicon is used for manufacturing of solar cell.
Advantages of Solar cell:
- Solar cell is fix at one place. There is no any moving part in it, therefore maintenance cost is negligible.
- It can be set up at remote areas also. So it solve the problems of electricity in that area.
Uses of solar cell:
Solar cell are used in
- Radio transmission system.
- TV relays stations.
- Traffic signals.
- Street lights
- Calculators and other toys.
- Artificial satellites.
- Space stations.
- Domestic use.
Answer the following questions
- State the principal of solar cell.
- Why do we prefer solar energy than any other?
- What are the uses of solar cell?
- State disadvantages of sonar cell.
- How much voltagewill be produced from one cell?