Answer
$E = 0.512~MeV$
Work Step by Step
In part (a) we found that the Compton wavelength for an electron is $~~2.43\times 10^{-12}~m$
We can find the energy of a photon with this wavelength:
$E = \frac{hc}{\lambda}$
$E = \frac{(6.63\times 10^{-34}~J~s)(3.0\times 10^8~m/s)}{2.43\times 10^{-12}~m}$
$E = 8.185\times 10^{-14}~J$
$E = (8.185\times 10^{-14}~J)(\frac{1~eV}{1.6\times 10^{-19}~J})$
$E = 5.12\times 10^5~eV$
$E = 0.512~MeV$
