# Homework Help: What sort of photon is this?

1. Nov 4, 2004

### stunner5000pt

A photon of frequency $$\nu$$ collides elastically with an electron at rest. The phton loses half its nergy in the collision an its final path makes a 60 degree angle with the original path. What is $$\nu$$ ? what sort of photon is this?

Well this is obviously the compton effect

$$\lambda_{1} - \lambda = \frac{h}{mc} (1 - Cos \phi ) = 1.21 * 10^12$$

Then Also the photon lost half it's energy so

$$\frac{h \nu}{2} = \frac{h \nu '}{2}$$
and figure that $$2 \lambda = \lambda '$$

and then lambda = 1.21 * 10^12?

then $$\nu = 4.04 * 10^21 Hz$$

which is a gamma ray?

am i right in this? i have my doubts about the lambdas

Also i have another thread i need some help would greatly appreciate with both! Thank you!!

https://www.physicsforums.com/showthread.php?t=51474

Last edited: Nov 4, 2004
2. Nov 5, 2004

### Staff: Mentor

Your thinking is correct...
...but watch those exponents. I assume you meant to write 1.21E-12.
redo that calculation.

Yep.

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