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. $5\times {10}^{-25}kg‘$, $1.5\times {10}^{-26}kg-m/s$
• C. Zero, $1.5\times {10}^{-26}kg-m/s$
• D. $5\times {10}^{-36}kg$, $1.36\times {10}^{-43}kg-m/s$

Answer 1

Answer: (A)

$5\times {10}^{-36}kg$, $1.5\times {10}^{-27}kg-m/s$

We know

$\lambda =h/mv$

$m=h/\lambda v$

$=\frac{6.626\times {10}^{-34}}{4400\times {10}^{-10}\times 3\times {10}^8}$

$=5\times {10}^{-36}Kg$

Momentum $=mv=5\times {10}^{-36}\times 3\times {10}^8=1.5\times {10}^{-27}kg-m/s$