The rays of the sun are focused on a piece of ice through a lens of diameter 5 cm , as a result of which 10 g ice melts in 10 minutes. The amount of heat received from the sun per unit area per minute is

Question

The rays of the sun are focused on a piece of ice through a lens of diameter 5 cm , as a result of which 10 g ice melts in 10 minutes. The amount of heat received from the sun per unit area per minute is, 4 c a l c m - 2 m i n - 1, 40 c a l c m - 2 m i n - 1, 4 J cm - 2 m i n - 1, 400 c a l c m - 2 m i n - 1

MARKS App · Accepted Answer

Mass of ice melted/ min = 10 10 = 1 g Quantity of heat used = 1 × 80 cal Area of lens = π r 2 = 3.14 2.5 2 = 19.625 c m 2 ∴ Amount of heat received per minute per cm 2 from sun = 80 19.625 = 4 c a l c m - 2 m i n - 1

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