The energy flux of sunlight reaching the surface of Earth is `1.388 xx10^(3)Wm^(-2)` . How many photons per square meter are incident on Earth per second? Assume the wavelength of photon at an average of 550 nm.

Explanation

Given : intensity `= ("Power")/("area") = 1.388xx 10^(3) Wm^(2)`
i.e., `E/(tA) = 1.388 xx 10^(3) , A = 1m^(2)`
i.e., `(nhc)/(t lambda A ) = 1.388 xx 10^(3)`
`therefore n/(At) = (1.388xx10^(3)xx 550 xx10^(-9))/ (6.625 xx 10 ^(34) xx 3 xx 10^(8))`
` = 38.41 xx 10^(20)`
`= 3.841 xx 10^(21)` Photons/`m^(2)`/s