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A family uses 8kW of power. (a) Direct solar energy is incident on the horizontal surface at an average rate of 200 W per square metre. If `20%` of this energy can be converted to useful electrical energy, how large an area is needed to supply 8kW? (a) Compare this area to that of the roof of a typical house. |
Answer» Let the area be A square metre. `:.` Total power `=200A`. Useful electrical energy produced `//` sec `=(20)/(100)(200A)=40A=8000(2wat t)` Therefore, `A=(8000)/(40)=200sq. m` This area is comparable to the roof of a large house of 250sq. metre. |
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