# Compton Scattering Question

Homework Statement:
A 0.662 MeV gamma ray Compton scatters from an electron at an angle of 60°. What is the energy of the scattered gamma ray? (Gamma rays are photons and are treated identically to x-rays in the analysis of Compton scattering.)
Relevant Equations:
E(gamma prime)= E(gamma)/(1+(E(gamma)/(mc^2)(1-cos(theta))) ?
I'm unsure of how to proceed here. Would I use the equation

E(gamma prime)= E(gamma)/(1+(E(gamma)/(mc^2)(1-cos(theta))) ?

Also, do I keep the .662 Mev as is or do I convert to joules?

## Answers and Replies

PeroK
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Homework Statement:: A 0.662 MeV gamma ray Compton scatters from an electron at an angle of 60°. What is the energy of the scattered gamma ray? (Gamma rays are photons and are treated identically to x-rays in the analysis of Compton scattering.)
Relevant Equations:: E(gamma prime)= E(gamma)/(1+(E(gamma)/(mc^2)(1-cos(theta))) ?

I'm unsure of how to proceed here. Would I use the equation

E(gamma prime)= E(gamma)/(1+(E(gamma)/(mc^2)(1-cos(theta))) ?

Also, do I keep the .662 Mev as is or do I convert to joules?
If you already have an equation for the change in energy, then why not use it?

Definitely use ##MeV##. Note that ##\frac{E}{mc^2}## is dimensionless. If you have ##E## in ##MeV##, then you need ##m## in ##MeV/c^2##. Which is much simpler than converting everything to SI units in this case.