Question

The momentum of a photon is $2\times {10}^{-16}gm-cm/sec$. Its energy is

• A. $0.61\times {10}^{-26}erg$
• B. $2.0\times {10}^{-26}erg$
• C. $6\times {10}^{-6}erg$
• D. $6\times {10}^{-8}erg$

Answer 1

The correct option is D. $6\times {10}^{-8}erg$.

Given,

Momentum = $p=2\times {10}^{-16}gm-cm/sec$

We know that,

The momentum of a photon of energy ($E$) is given by,

$p=\frac{E}{c}$

$\Rightarrow E=p\times c=2\times {10}^{-16}\times (3\times {10}^{10})=6\times {10}^{-6}erg.$