Question

A plane light wave of intensity I = 0.20 W/cm² falls on a plane mirror surface with reflection coefficient ρ = 0.8. The angle of incidence is 45°. In terms of the corpuscular theory find the magnitude of the normal pressure exerted by light on that surface.

Answer 1

Suppose the mirror has a surface area A. 

The incident bean then has a cross section of A cos θ and the incident energy is I A cos θ  ; Then the momentum transfered per second ( = Force ) is from the last problem