# Compton effect and visible light

1. Feb 7, 2006

### UrbanXrisis

why is it extremely dificult to observe the compton effect using visible light?

is it because visible light does not have a short enough wavelenght to excite the electrons?

2. Feb 7, 2006

### SpaceTiger

Staff Emeritus
Compton scattering becomes noticable when the energy of the light is comparable to the rest energy of the electron (~511 keV, hard X-rays). Visible light is much less energetic than this (~few eV), so the scattering process can conserve energy and momentum without a significant change in the wavelength of the photon.

3. Feb 7, 2006

### UrbanXrisis

does wavelength tell you the energy?

4. Feb 7, 2006

### SpaceTiger

Staff Emeritus
Yes. For a photon,

$$E=h\nu=\frac{hc}{\lambda}$$

5. Feb 7, 2006

### UrbanXrisis

so my assumption that visible light does not have a short enough wavelenght to excite the electrons is correct? since thei wavelenght is long, making energy low, hence, not enough eV to excite the electron?

6. Feb 7, 2006

### SpaceTiger

Staff Emeritus
The electron can receive both energy and momentum from a visible photon, but both would be just a tiny fraction of its rest energy. But yes, that's basically right.