A parallel beam of monochromatic light of wavelength 663 nm is incident on a totally reflection plane mirror. The angle of incidence is `60^@` and the number of photons striking the mirror per second is `1.0xx10^19`. Calculate the force exerted by the light beam on the mirror.

Answer

A

Explanation

Force = Rate of change of momentum
`=2 [N] [(h)/(lambda)]. cos 60^@`
N = number of photons striking per second
`(h)/(lambda) = momentum of one photn.