Question

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

• A. $1.6\times {10}^{-19}$
• B. $1.6\times {10}^{-2}$
• C. $1.6\times {10}^{-24}$
• D. $1.6\times {10}^{-27}$

Answer 1

The correct option is C $1.6\times {10}^{-24}$

$\begin{array}{c}\text{Energy of a plooton}\left(E\right)=\frac{hc}{\lambda }\\ \text{and de broglie wavelength}\left(\lambda \right)=\frac{h}{p}\end{array}$

$\begin{array}{c}\therefore E=PC\left(P\text{is momentum}\right)\\ \text{or}P=\frac{E}{C}\\ P=\frac{3\times {10}^3\times 1.6\times {10}^{-19}}{3\times {10}^8}\\ P=1.6\times {10}^{-24}kg-m/s\end{array}$