Compton Scattering: Difficulties with Part C

[Chowie]

Homework Statement

I'm having difficulty with part C of this question:

Homework Equations

The Attempt at a Solution

Using the above equations I correctly calculated the new wavelength of the photon after the collision and using the equations for the photon energies I calculated the energy of the photon before and after the collision to get the change in energy, which I calculated to be 380 eV (I calculated it a few times at varying degrees of accuracy at around 379.6 but the website rounds it up to 380)

Am I doing anything wrong here? Is there some relativistic stuff that I haven't accounted for or is the answer given simply wrong. I'm just using wikipedia and my textbook and it seems like 380 eV should be correct.

If I get a few people here saying that I haven't done anything wrong then I'll email my tutor and get him to change the answer.

Cheers for any replies.

 

[Redbelly98]

If it's a matter of significant figures, perhaps you should round to 1 sig. fig.

 

[Chowie]

I submitted a few answers which all when I clicked "my answers" came out to be the same rounded to 380

 

[Redbelly98]

Looks to me like you have solved this correctly, so I am thinking either a sig figs issue or possibly they want a negative number, to indicate the lower energy of the scattered photon.

If you use a more accurate wavelength change of 5.68x10^-4 nm for the energy calculation, you get the 359 eV that is shown in your first figure. However, using just 1 sig fig as I suggested before the answer rounds to 400 eV.

 

[Chowie]

Cr*p so I should have used the change in wavelength given to me rather than recalculating it? Bo**ocks, guess I just lost some marks. Thanks for the help, at least you helped one of my friends out who had a similar issue.