Nuclei - Result Question 28
29. A nucleus of mass M emits a photon of frequency $v$ and the nucleus recoils. The recoil energy will be
(a) $Mc^{2}-hv$
(b) $h^{2} v^{2} / 2 Mc^{2}$
(c) zero
(d) $h \nu$
[2011]
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Answer:
Correct Answer: 29. (b)
Solution:
- (b) Momentum
$Mu=\frac{E}{c}=\frac{h \nu}{c}$
Recoil energy
$\frac{1}{2} Mu^{2}=\frac{1}{2} \frac{M^{2} u^{2}}{M}=\frac{1}{2 M}(\frac{h v}{c})^{2}=\frac{h^{2} v^{2}}{2 Mc^{2}}$
