Dual Nature of Radiation and Matter - Result Question 48

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50. The momentum of a photon of energy $1 MeV$ in $kg m / s$, will be

======= ####50. The momentum of a photon of energy $1 MeV$ in $kg m / s$, will be

3e0f7ab6f6a50373c3f2dbda6ca2533482a77bed:content/english/neet-pyq-chapterwise/physics/dual-nature-of-radiation-and-matter/dual-nature-of-radiation-and-matter—result-question-48.md (a) $7 \times 10^{-24}$

(b) $10^{-22}$

(c) $5 \times 10^{-22}$

(d) $0.33 \times 10^{6}$

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Answer:

Correct Answer: 50. (c)

Solution:

  1. (c) $1 MeV=10^{6} \times 1.6 \times 10^{-19}$ joule

Momentum of photon,

$p=\frac{E}{c}=\frac{1.6 \times 10^{-13}}{3 \times 10^{8}}$

$p=\frac{1.6}{3} \times 10^{-21}=\frac{16}{3} \times 10^{-22}$

$p=5 \times 10^{-22} kg m / sec$

Rest mass of photon is zero. But its effective mass is given by

$E=m c^{2}=h v$

$\Rightarrow m=\frac{E}{c^{2}}$

$\therefore$ Momentum of photon, $p=mc=\frac{E}{c^{2}} \times C$

$\Rightarrow p=\frac{E}{c}$