Class 10 science Solutions English Medium

Non-Conventional/Alternative Sources of Energy

Causes to look at alternative sources of energy: 

(i) The demand of energy increasing day by day, but these all demands cannot be completed by conventional sources of energy. 

(ii) Conventional sources are limited in nature. 

(iii) Conventional sources like fossil fuels are very low that can be finished in future. 

(iv) The Most of the conventional sources of energy is non-renewable. 

1. Solar Energy: 

The energy obtained from sun is known as solar energy. 

Uses of solar energy: 

There are two technologies in which solar energy is used.

(A) Solar Cooker 

(B) Solar Panel

(A) Solar Cooker:

Solar cooker is a device which is used to cook food by using solar energy. 

Principle of solar energy: 

There are two principles on which solar cooker works. 

(i)    Black colour absorbs more heat than other.

(ii)   Use of glass plate which produces green-house effect inside the cooker. 

Structure and function of Solar cooker: 

Solar cooker just like a box and its internal surfaces are coloured with black colour. Solar cookers are covered with a glass plate. Which traps heats to go out from box and shows green house effect. A black surface absorbs more heat as compared to a white or a reflecting surface under identical conditions. Solar cookers and solar water heaters use this property in their working. Some solar cookers achieve a higher temperature by using mirrors to focus the rays of the Sun. 

(B) Solar Panel : 

​A large number of solar cells are, combined in an arrangement called solar cell panel that can deliver enough electricity for practical use.

Solar Cells: Solar cells are devices which are made of silicon and they convert solar energy to electrical energy. 

• Solar cells are made up of silicon. 
• Silver is used to interconnect the solar cells to each other to form solar panel. 
• Domestic use of solar cells is limited due to its high cost.
• A typical cell develops a voltage of 0.5 –1 V and can produce about 0.7 W of electricity when exposed to the Sun.

Three uses of solar cells.

(i) Artificial satellites and space probes like Mars orbiters use solar cells as the main source of energy.

(ii) Radio or wireless transmission systems or TV relay stations in remote locations use solar cell panels.

(iii) Traffic signals, calculators and many toys are fitted with solar cells.

Advantage of solar cells: 

(i) They have no moving parts, require little maintenance.

(ii) They work quite satisfactorily without the use of any focussing device.

(iii) They can be set up in remote area where laying of a power transmission line
is more expensive and not commercially viable.

(iv) It is alternative source of energy. 

(v) It does not produce pollutions and does not harm environment.         

Limitation of solar cells: 

(i) These devices are useful only at certain times during the day.

(ii) They do not perform good work during rainy days. 

(iii) There is limited production of electricity by solar cells. 

(iv) They have high cost and low efficiency.