Work, Power and Energy
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Question : 23
Total: 30
A family uses 8 kW of power.
(a) Direct solar energy is incident on the horizontal surface at an average rate of 200 W per square meter. If 20% of this energy can be converted to useful electrical energy, how large an area is needed to supply 8 kW?
(b) Compare this area to that of the roof of a typical house.
(a) Direct solar energy is incident on the horizontal surface at an average rate of 200 W per square meter. If 20% of this energy can be converted to useful electrical energy, how large an area is needed to supply 8 kW?
(b) Compare this area to that of the roof of a typical house.
Solution:
Let the area be A square metre.
∴ Total power = 200 A.
Useful electrical energy produced/second
=
( 200 A ) = 40 A = 8000 ( watt )
Therefore,A =
= 200 s q . m
This area is comparable to the roof of a large house of 250 sq. metre.
∴ Total power = 200 A.
Useful electrical energy produced/second
Therefore,
This area is comparable to the roof of a large house of 250 sq. metre.
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