Verified Solution • 2025–26 Session
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Q5.23: NCERT Physics - Part 1 WORK, ENERGY AND POWER 5.23 Solution: A family uses 8 kW of power. (a) Direct solar energy is…
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.
Step-by-Step Verified Solution
**Answer:** (a) Area = 200 m_ (b) Much larger than a typical house roof.
**Step-by-Step Explanation:**
(a) Useful power per m_ = 0.20 _ 200 = 40 W/m_.
Area needed = 8000/40 = 200 m_.
(b) A typical house roof is about 50-100 m_, so this area is much larger.
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