Question

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

• A. $2.95\times {10}^{-23}$
• B. $1.6\times {10}^{-21}$
• C. $1.6\times {10}^{-24}$
• D. $1.6\times {10}^{-27}$

Answer 1

The correct option is A

$2.95\times {10}^{-23}$

If the energy of the electron is $E=3KeV=3\times {10}^{3}eV=3\times 1.6\times {10}^{-16}Joule$

Then the momentum ,$p$ is given by $p=\sqrt[2]{22mE}=\sqrt[2]{22\times 9.1\times {10}^{-31}\times 4.8\times {10}^{-16}}=2.95\times {10}^{-23}Kgm/s$

Where $m=9.1\times {10}^{-31}Kg$ is mass of electron.