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Grade 12Modern Physics

A stationary nucleus of mass 24u emits a ¥ photon. The energy of the emited photon is 7MeV. Find the recoil energy of the nucleus?(ans:-1.1MeV).

Profile image of rajan jha
15 Years agoGrade 12
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1 Answer

Profile image of vikas askiitian expert
ApprovedApproved Tutor Answer15 Years ago

in gama decay there is no change in mass number...

initially nucleous was at rest ,due to internal forces it will move after giving a gamma photon..

so we can apply conservation of momentam here

final momentam = initial momentam = 0

P(gamma photon) + P(nucleous) = 0  .......................1

  energy of photon = 7Mev

   p(photon) = E/c                        (c is speed of light , E =7Mev (given) )

 p(nucleous) = -E/c             ( from eq 1)

  kinetic energy = P2/2m = E2/2mc2 

now put E , C & m ,u will get the  1.1Mev ans