A parallel beam of uniform, monochromatic light of wavelength 6600 Å has an intensity of `900 Wm^(-2)`. The number of photons in `1 mm^3` of this radiation are `1xx 10^(X)` then find out value of X.

Explanation

Energy incident in `1 m^(2)` in 1 sec.
E=900 J
`(hc)/(lambda) nxx1xx3xx10^(8) =900`
`n=10^(13)` photons`//m^(3)`
`n=10^(4)` photons/`mm^(3)`