Question

100. What should be the mass of the photon of sodium
if its wavelength is 58944, the velocity of light is
3 x 108 metre/second and the value of h is
6.6252 x 10-34 kg mº/s ?
(1) 3.746 x 10-26 kg (2) 3.746 x 10-30 kg
(3) 3.746 x 10-34 kg (4) 3.746 x 10-36 kg​

Answer 1

$\large \bold{ \underline{ \underline{ \sf \: Correct \: question : \: \: \: }}}$

What should be the mass of the photon of sodium if its wavelength is 58944 Å , the velocity of light is$\sf 3 \times {10}^{8} \: m/s$and the value of h is $\sf 6.6 × {10}^{ - 34} \: \: kg \: {m}^{ - 2} {s}^{ - 1}$

$\large \bold{ \underline{ \underline{ \sf \: Solution : \: \: \: }}}$

Given ,

$\sf Wavelength = 5894 \: A = 5894 \times {10}^{ - 10}m$

$\sf Planck's \: constant ( h ) = 6.6 × {10}^{ - 34} \: \: kg \: {m}^{ - 2} {s}^{ - 1}$

$\sf Velocity = 3 \times {10}^{8} \: m/s$

We know that

$\fbox{ \fbox{\sf Mass \: of \: photon = \frac{h}{ \: \: Velocity \times Wavelength \: \: } }}$

$\to \sf Mass \: of \: photon = \frac{6.6 \times {10}^{ - 34} }{3 \times {10}^{8} \times 5894 \times {10}^{ - 10} } \\ \\ \to \sf Mass \: of \: photon =3.73 \times {10}^{ - 36} \: kg$

Hence , the required mass of the photon of sodium is $\sf 3.73 \times {10}^{ - 36} \: kg$