# Damping Term of a Photon

1. Sep 6, 2005

### Watts

Typically photon attenuation is determined by the equation $I = I_0 \cdot e^{ - (\mu \cdot z)}$. The variable mu is the linear attenuation coefficient and z is the distance traveled through the substance of transport. Is it safe to say that $I_0 \cdot e^{ - (\mu \cdot z)}$ is the damping term of the electromagnetic wave for the photon? My question is can I write $I(z,t) = I_0 \cdot e^{ - (\mu \cdot z)} \cdot e^{i \cdot (k \cdot z - \omega \cdot t)}$.

Last edited: Sep 6, 2005
2. Sep 7, 2005

### Broken

Yes. Carry on.

3. Sep 7, 2005

### Watts

Photon

I can’t carry on any further my question is stated. Am I being unclear?

4. Sep 8, 2005

### ehild

What do you mean on I? If it is electric or magnetic field intensity, your formula is right if that wave travels in direction z, in a homogeneous isotropic medium. If I is the intensity your formula is wrong. Moreover, the wave is damped, not the photon. Damping means that the number of photons decreases with the distance travelled in an absorbing medium.

ehild

5. Sep 8, 2005

### Watts

Intensity

I is the intensity.

6. Sep 8, 2005

### ehild

The intensity changes as

$$I=I_0 e^{-\mu z}$$

ehild