Question

What is the mass of photon in motion?

Answer 1

Step 1: Write the expression of energy of photon having plank constant $h$and frequency $f$.

$E=hf$

Write the expression for Einstein's mass energy equivalence is

$E=m{c}^2$

Here,$m$ is mass of photon and $c$ speed of photon.

Step 2: Substitute $m{c}^2$ for $E$ in the expression of energy of photon.

$$\begin{gathered} m{c}^2=hf \\ m=\frac{hf}{c^2} \end{gathered}$$

Hence, mass of photon is $\frac{hf}{c^2}$.