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Question
At the given point of time, the earth receives energy from the sun at 4 cal cm–2 min–1. Determine the number of photons received on the surface of the Earth per cm2 per minute. (Given: Mean wavelength of sunlight = 5500 Å)
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Solution
E = 4 calorie = 4 × 4.184 J
λ = 5500 Å
Number of photons received on the surface of the earth, from E = nhv
n = `("E"λ)/"hc"`
= `(4 xx 4.184 xx 5500 xx 10^-10)/(6.6 xx 10^-34 xx 3 xx 10^8)`
= `(9.2048 xx 10^-10)/(19.8 xx 10^-26)`
= 4648 × 1016
= 4.648 × 1019
n = 4.65 × 1019
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