Question

The radiation force experienced by a body exposed to radiation of intensity $I_0$, assuming the surface of the body to be perfectly absorbing is

• A. $\frac{Rh{I}_0}{2c}$
• B. $\frac{\pi Rh{I}_0}{c}$
• C. $\frac{Rh{I}_0}{c}$
• D. $\frac{\pi R^2{I}_0}{c}$

Answer 1

The correct option is C $\frac{Rh{I}_0}{c}$

The effective area on which light incident,

$A=\frac{2Rh}{2}=Rh$

Since, surface is perfectly absorbing, so the force exerted by the rays will be,

$F=\frac{IA}{c}=\frac{I_0\left(Rh\right)}{c}=\frac{Rh{I}_0}{c}$

Hence, option $\left(\text{D}\right)$ is correct.