# Dispersion Relation

1. Oct 30, 2008

### yellowgold

What is the dispersion relation in photons? "(Frequency momentum or etc)

2. Oct 31, 2008

### clem

A dispersion relation is the relation between the frequency omega and the wave number k.

3. Oct 31, 2008

### lightarrow

Or, said in another way, how the phase speed of light (and hence, the index of refraction) depends on the light's frequency in that specific material/medium.

4. Oct 31, 2008

### malawi_glenn

lightarrow, why restrict yourself to light? The dispersion relation are for waves, all waves, as far as I have understood it.

5. Oct 31, 2008

### lightarrow

Ah, yes, of course, but the OP asked about photons.

6. Nov 1, 2008

### malawi_glenn

haha yeah now I saw he did! ;-)
Though he asked what dispersion relation was "in general"

7. Nov 1, 2008

### Avodyne

The dispersion relation for photons is
$$\omega=|\vec k|c.$$

8. Nov 1, 2008

### yellowgold

Thank you very much everybody. I understood it.