Question

What is minimum energy of photon required for electron proton pair.

Answer 1

Solution

According to electron proton pair production theory minimum 1.02 MeV energy is required to produce electron-proton pair through photons.

This can be shown as below

Suppose both produced electron and proton are in rest then using energy conservation

$E_{photon}=m_oc^2+m_oc^2$

For both rest mass energy is

$m_oc^2= 0.51MeV$

So mininum energy become

$2\times0.51MeV=1.02MeV$