Question

Momentum of $\gamma$ -ray photon of energy 3 keV in km/s will be

• A. $1.6\times {10}^{-19}kgm{s}^{-}1$
  
• B. $1.6\times {10}^{21}kgm{s}^{-}1$
  
• C. $1.6\times {10}^{-24}kgm{s}^{-}1$
  
• D. $1.6\times {10}^{-27}kgm{s}^{-}1$
  

Answer 1

The correct option is A $1.6\times {10}^{-19}kgm{s}^{-}1$

$\begin{array}{c}Momentumofphoton=\frac{h}{\lambda }\\ Energyofphoton=\frac{hc}{\lambda }\\ 3KeV=\frac{hc}{\lambda }\\ \frac{h}{\lambda }=3\times 1.6\times {10}^{-19}\times {10}^3\\ \frac{h}{\lambda }=3\times 1.6\times {10}^{-19}\times {10}^3\times {10}^{-3}\\ =1.6\times {10}^{-19}.\end{array}$

Option A.