At the given point of time, the earth receives energy from sun at `4 cal cm^(-2) mi n^(-1)` .Determine the number of photons received on the surface of the Earth per `cm^(2)` per minute. (Given `:` Mean wavelength of sun light `= 5500 Å` )

Explanation

`{:("Number of photons received on the surface of the earth,",,E = "4 calorie"),("from E =" n h upsilon,,=4 xx 4.184 J),(n = (Elambda)/(hc),,lambda = 5500 Å):}`
`= (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 xx 10^(16)`
`= 4.648 xx 10^(19)`
`n = 4.65 xx 10^(19)`