A family uses 8 kW of power. (a) Direct ...

Work, Power and Energy

Question : 23 of 30

Marks: +1, -0

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.

Solution:

Let the area be A square metre.

∴ Total power = 200 A.

Useful electrical energy produced/second

= \frac{20}{100}(200 A)=40 A=8000(\text{watt})

Therefore,

A= \frac{8000}{40}=200 \text{sq.m}

This area is comparable to the roof of a large house of 250 sq. metre.

Go to Question:

Prev Question

Next Question