# Compton Effect

#### viona

Hi every one

In Compton effect I understand that the electron is considered free electron because the energy of the incident photon is very much larger than the binding energy of the atomic electron. But I am not sure why the electron is considered to be at rest (v=0). please help.
Thanks.

#### studiot

Here is a compton explanation and calculation worked out for a blue photon and an electron.
At the end they ask you to calculate the velocity of the electron Can you do this ? I make it 2.6 x 10^7 m/s
Compare this with the velocity of light 3 x 10^8 m/s.
So the photon is going a tad over 10 times faster than the elctron.
This is why the electron velocity is ignored, but not its momentum.

topsquark and viona

#### viona

Here is a compton explanation and calculation worked out for a blue photon and an electron.
At the end they ask you to calculate the velocity of the electron Can you do this ? I make it 2.6 x 10^7 m/s
Compare this with the velocity of light 3 x 10^8 m/s.
So the photon is going a tad over 10 times faster than the elctron.
This is why the electron velocity is ignored, but not its momentum.

#### Woody

I just tried it and it was OK for me.
Do you have a reader for pdf style documents?

viona

#### studiot

Sorry Viona, I don't seem to be having much luck with your threads as I lost a detailed explanation in your last one somehow.
Anyway the extension at the end is .pdf so it is a pdf file which your browser may not be set up to open, especially if you are using a phone ?
If you can't download the pdf let us know and I will see what can be done - it really is a very clear explanation.

viona

There you go.

#### Attachments

• 339.9 KB Views: 2
viona and topsquark

There you go.