Q71 / 90 · JEE Main 2021 (20 Jul Shift 1) · Physics

A nucleus of mass M emits γ-ray photon of frequency v. The loss of internal energy by the nucleus is: [Take c as the speed of electromagnetic wave]

  • A
    hv
  • B
    0
  • C
    hv1-hv2Mc2
  • Correct answer
    D
    hv1+hv2Mc2

Solution

Energy of γ ray Eγ=hv

Momentum of γ ray Pγ=hλ=hvc
Total momentum is conserved.

P→γ+P→Nu=0
where P→Nu= momentum of decayed nuclei

⇒Pγ=PNu
⇒hvc=PNu
⇒KE of nuclei

=12Mv2=PNu22M=12Mhvc2
Loss in internal energy =Eγ+KENu
=hv+12Mhvc2
=hv1+hv2Mc2

Hence, the correct answer is option: 'D'.

Relevant Questions