Question

If the wavelength of a radiation is of the order of ${10}^{-15}\text{m}$, then the momentum associated with the photon has an order of -

• A. ${10}^{-19}\text{kg-m/s}$
• B. ${10}^{19}\text{kg-m/s}$
• C. ${10}^{-18}\text{kg-m/s}$
• D. ${10}^{18}\text{kg-m/s}$

Answer 1

The correct option is C ${10}^{-18}\text{kg-m/s}$

The momentum associated with a photon is given by,

$p=\frac{h}{\lambda }$

Order of Planck constant is ${10}^{-33}\text{J-s}$

Given order of wavelength is ${10}^{-15}\text{m}$

So, order of momentum will be,

$\frac{{10}^{-33}}{{10}^{-15}}={10}^{-18}\text{kg-m/s}$

Hence, option $\left(C\right)$ is the correct answer.