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The sun gives light at the rate of 1400W...

The sun gives light at the rate of `1400Wm^(-2)` of area perpendicular to the direction of light. Assume `lamda(sunlight)=6000A`. Calculate
A.the number of photons per second arriving at `1 m^2` area at earth.
B. the number of photons emitted from the sun per second assuming the average radius of the Earth's orbit is `1.49xx10^(11)` m.

Text Solution

Verified by Experts

(a) Energy of a photon `E = (hc)/(lambda) = (12400)/(6000) = 2.06 eV = 3.3 xx 10^(-19) J`
Photon fulx `= (IA)/(E) = (1400 xx 1)/(3.3 xx 10^(-19)) = 4.22 xx 10^(21) "photons"//"sec"`.
(b) Number of photons emitted per second `n = (P)/(E) = (IA)/(E) = (1400 xx 4pi xx (1.49 xx 10^(11))^(2))/(3.3 xx 10^(-19)) = 1.18 xx 10^(45)`
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