Question

The mass of a photon with wavelength $ 3.6\,\mathring{A} $ is:

• A. $ 6.135\times {{10}^{-29}}kg $
• B. $ 3.60\times {{10}^{-29}}kg $
• C. $ 6.135\times {{10}^{-33}}kg $
• D. $ 3.60\times {{10}^{-27}}kg $

Answer 1

Answer: (C)

We know that
$E =m c^{2}=\frac{h c}{\lambda} $
$\therefore \lambda =\frac{h}{m c} $
or $\quad m =\frac{h}{\lambda c} $
Where, $\lambda=$ wavelength of photon
$h =$ planck's constant
$m =$ mass of photon
$c =$ velocity of light
Given, $ \lambda =3.6 \,\mathring{A}=3.6 \times 10^{-10} m $
$\therefore m =\frac{6.62 \times 10^{-34}}{3.6 \times 10^{-10} \times 3 \times 10^{8}} $
$=6.135 \times 10^{-33} kg$