A beam of white light is incident normally on a plane surface absorbing `(70%)` of the light and reflecting the rest. If the incident beam carries 10 W of power , find the force exerted by it on the surface .

Answer

`(1.3xx30)/(3xx10^(8))=1.3xx10^(-7)`

Explanation

change in momentum
`DeltaP=0.7(h)/(lambda)+2xx0.3xx(h)/(lambda)`
`=1.3(P)/(c )=1.3xx(30)/(3xx10^(8))=1.3xx10^(-7)N`.