# Basic Compton Scattering

1. Mar 11, 2013

### bmb2009

1. The problem statement, all variables and given/known data

A photon carrying energy of 40keV scatters from an electron initially at rest. what is the maximum energy the electron can have?

2. Relevant equations

3. The attempt at a solution

I tried using conservation of energy

Initial: 40keV (energy of photon) + mc^2 (rest energy of electron)
Final: To have the most energy all the energy of the photon should be transfer to kinetic energy of the electron correct?

so wouldn't the final energy just be the rest energy of the electron + the kinetic energy of the electron? Not sure where im missing an idea..thanks for the help

2. Mar 11, 2013

### TSny

There's something else that needs to be conserved besides energy.

3. Mar 11, 2013

### bmb2009

I know momentumn does too but how do i combine these two to get the total final energy?

4. Mar 11, 2013

### TSny

If you're allowed to use the well-known http://hyperphysics.phy-astr.gsu.edu/%E2%80%8Chbase/quantum/comptint.html [Broken] then you will not need to go through the algebra of combining the energy and momentum equations.

If you are required to derive the result starting from conservation of energy and momentum, then what would each conservation equation look like?

Note that "scattering" implies that there will be a photon present after the "collision" as well as before.

Last edited by a moderator: May 6, 2017
5. Mar 11, 2013

### bmb2009

Yes i derived that equation but i still don't see the connection to the energy of the electron... I assume that to maximize the energy of the electron the change in wavelength should be largest at an angle of pi correct? that would yield 2h/mc=delta lambda but now how do i find the energy of the electron??

6. Mar 11, 2013

### bmb2009

ahhh nevermind i figured it out.. thanks for the guidance..it's appreciated!

7. Mar 11, 2013

ok, good!