# Damping Term of a Photon

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 $I(z,t) = I_0 \cdot e^{ - (\mu \cdot z)} \cdot e^{i \cdot (k \cdot z - \omega \cdot t)}$.

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Broken
Yes. Carry on.

Watts
Photon

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

Homework Helper
Watts said:
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 $I(z,t) = I_0 \cdot e^{ - (\mu \cdot z)} \cdot e^{i \cdot (k \cdot z - \omega \cdot t)}$.

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 traveled in an absorbing medium.

ehild

Watts
Intensity

I is the intensity.

Homework Helper
Watts said:
I is the intensity.

The intensity changes as

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

ehild