A photon strikes an electron of mass m that is initially at rest, creating an electron-positron
pair. The photon is destroyed and the positron and two electrons move
off at equal speeds along the initial direction of the photon. The energy of the
photon was ?
The Attempt at a Solution
are we suppose to use momentum conservation?
or kinetic energy conservation?
do we have to factor in relativistic effects?
the answer is 4mc2
but i have totally no idea at all how to get that
i think the final mass = 1.5 m ? where m = electron mass
because positron and electron pair = 0.5 m , then add in the other stationary electron so 1.5m ?
this is confusing . greatly appreciate any help thanks!