A sphere of radius 1.00 cm is placed in the path of a parallel beam of light of large aperture. The intensity of the light is 0.50 W `cm^-2`. If the sphere completely absorbs the radiation falling on it, find the force exerted by the light beam on the sphere.

Explanation

If a perfectly reflecting solid sphere of radius 'r' is kept in the path of a parallel beam of light of large aperture if intensity is l ,
` Force = pi r^(2)l/ c `
`l = 0.5 W / m^(2)`
`r = 1cm, c = 3 xx 10^(8) m / s `
`Force = pi xx (1) xx 0.5 / 3 xx10^(8) `
`= 3.14 xx 0.5 / 3 xx 10^(8)`
` 0.523 xx 10^(-8)`
` = 5.2 xx 10^(-9) N.