Question

A photon of wavelength $4400\, \mathring{A}$ is passing through vacuum. The effective mass and momentum of the photon are respectively

• A. $5 \times 10^{-36} kg ,\, 1.5 \times 10^{-27} kg - m / s$
• B. $5 \times 10^{-35} kg ,\, 1.5 \times 10^{-26} kg - m / s$
• C. Zero, $1.5 \times 10^{-26} kg - m / s$
• D. $5 \times 10^{-36} kg ,\, 1.67 \times 10^{-43} kg - m / s$

Answer 1

Answer: (A)

$p=\frac{h}{\lambda}=\frac{6.6 \times 10^{-34}}{4400 \times 10^{-10}}$
$=1.5 \times 10^{-27} kg \cdot m / s$
and mass $m=\frac{p}{c} =\frac{1.5 \times 10^{-27}}{3 \times 10^{8}}$
$=5 \times 10^{-36} kg$