A parallel beam of monochromatic light of wavelength 663 nm is incident on a totally reflecting plane mirror. The angle of incidence is `60^@` and the number of photons striking the mirror per second is `1.0 xx 10^19`. Calculate the force exerted by the light beam on the mirror.

Explanation

Here , ` lambda = 663 xx 10^(-9) m` ,
`theta = 60^@ , n = 1 xx 10^(19)`
`lambda = h / p = 6.63 xx 10^(-24) / 663 xx10^(-9) = 10^(-27)`
Force exerted o the well
`= n xx 9 xx mV cos theta - (- mn cos theta ) 2 n m V cos theta `
`= 2 xx 1 xx 10^(19) xx 10^(-27) xx 1 / 2`
` 1 xx 10^(-8) N.