Light of intensity is incident on a perfectly absorbing metal surface of area
making an angle of $60^{\circ}$ with the normal. If the force exerted by the photons on the surface is
(in Newton), then the value of
is :
5
2
1
3
We will be calculating everything per unit time.
The effective area for the light on the surface is
Energy falling on the surface = intensity Effective area
Momentum carried by the light per sec
So,