Question

The rest mass energy of an electron as well of an positron is 0.51 MeV. If a $\gamma$-photon of energy 2.42 MeV produces an electron – positron pair, then the kinetic energy of each particle is

• A. 0.2 MeV
• B. 1.5 MeV
• C. 0.7 MeV
• D. 0.4 MeV

Answer 1

The correct option is C

0.7 MeV

TE = Energy of positron and electron

+

Sum of KE of positron and Electron

$\therefore 2.42=2\times 0.51+totalKE$

$\therefore TotalKE=1.4M_{e}V$

$\therefore KEofeachparticle=0.7M_{e}V$