Question

The mass of a photon with a wavelength equal to $ 1.54\times 10^{-8}cm$ is:

• A. $ 0.8268\times 10^{-34}kg $
• B. $ 1.2876\times 10^{-33}kg$
• C. $ 1.4285\times 10^{-32}kg$
• D. $ 1.8884\times 10^{-32}kg$

Answer 1

Answer: (C)

We know that $\lambda=\frac{h}{m v}$
$\therefore m=\frac{h}{\lambda v}$
The velocity of photon
$(v)=3 \times 10^{8} m\, \sec ^{-1}$
$\lambda=1.54 \times 10^{-8} cm$
$=1.54 \times 10^{-10} metre$
$\therefore m=\frac{6.626 \times 10^{-34} Js }{1.54 \times 10^{-10} m \times 3 \times 10^{8} m\, \sec ^{-1}}$
$=1.4285 \times 10^{-32} kg$