Question

A gamma ray photon creates an electron-positron pair. If the rest mass energy of an electron is `0.5 MeV` and the total `K.E.` of the electron-position pair is `0.78 MeV`, then the energy of the gamma ray photon must be.
A. 0.78 MeV
B. 1.78 MeV
C. 1.28 MeV
D. 0.28 MeV

Answer 1

Correct Answer - B
(b) Energy of `gamma-ray` photon `= 0.5 + 0.5 + 0.78`
=`1.78 MeV`.