Question

A parallel beam of light is incident normally on a plane surface absorbing 40% of the light and reflecting the rest . If the incident beam carries 10W of power , find the force exerted by it on the surface .

Answer 1

Solution. We have the following formula:
F=P/c (1+ρ),
where c – speed of light, ρ – coefficient of reflection, so
F=10W/(3∙〖10〗^8 m/s) (1+0.6)=5,3∙〖10〗^(-8) N.
Answer: 5,3∙〖10〗^(-8) N.