Question

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

• A. ${0.8268\times 10}^{-34}$
• B. ${1.2876\times 10}^{-33}$
• C. ${1.4285\times 10}^{-32}$
• D. ${1.88\times 10}^{-36}$

Answer 1

Answer: (C)

${1.4285\times 10}^{-32}$

By De Broglie wavelength formula

$\lambda =\frac{h}{mv}$

velocity of photon $c=3\times {10}^{8}m/s$

$\frac{1}{m}=\frac{\lambda v}{h}$

$\frac{1}{m}=\frac{1.54\times {10}^{-8}\times {10}^{-2}\times 3\times {10}^8}{\mathrm{6.62.6}\times {10}^{-34}}$

$\frac{1}{m}=6.97\times {10}^{32}$

$m=\frac{1}{6.97\times {10}^{32}}=1.4285\times {10}^{-33}kg$

$Ans-C$