# What is the difference in amplitude between red and blue photons?

1. Jul 21, 2005

### mcgucken

What is the difference in amplitude between red and blue photons? Which has a great amplitude? Where is the definition of a photon's amplitude defined?

2. Jul 21, 2005

### Edgardo

Hello mcgucken,

a photon does not have an amplitude, an amplitude for a photon is not defined (unless you mean the probability amplitude). The red and blue photon differ by their wavelength. For example a red photon $\lambda = 800$nm and blue photon $\lambda = 400$nm.

When you talk about amplitudes you usually refer to electromagnetic waves amplitudes. But one single photon does not have an amplitude.

3. Jul 22, 2005

### Meir Achuz

A single photon does have an amplitude.
The amplitude of the vector potential in an electromagnetic wave is
given by Nh\nu, where N is the number of photons in the wave.
Amplitude does not relate to color, which depends only on frequency (or wavelength).