Question

The momentum of a photon of frequency $5\times {10}^{17}{s}^{-1}$ is nearly :

• A. $1.1\times {10}^{-24}kgm{s}^{-1}$
• B. $3.33\times {10}^{-43}kgm{s}^{-1}$
• C. $2.27\times {10}^{-40}kgm{s}^{-1}$
• D. $2.27\times {10}^{-38}kgm{s}^{-1}$

Answer 1

The correct option is A $1.1\times {10}^{-24}kgm{s}^{-1}$

Wavelength $\lambda =h/mv$ where h= planck's constant, m= mass, v= velocity.

Again $\lambda =c/f$ where f = frequency.

Here velocity = v = c

So, momentum = $h\times f/c=(6.626\times {10}^{-34}\times 5\times {10}^{17})/3\times {10}^8$

$=1.1\times {10}^{-24}kgm{s}^{-1}$.

The correct option is A