Photon
Contents
Key Stage 5
Meaning
Photons (\(\gamma\)) are bosons responsible for mediating the electromagnetic interaction and are the particle associated with electromagnetic waves.
About Photons
- The photon is denoted with the lower case Greek letter \(\gamma\) (gamma).
- Photons carry energy from one place to another.
- Photons have no mass or charge
About Virtual Photons
- Virtual photons a model for the mechanism of action of the electromagnetic interaction, but they are not strictly 'real'.
- Virtual photons have no mass and therefore can mediate the electromagnetic interaction over an infinite range.
- Virtual photons carry momentum without carrying mass and are therefore able to change the direction of motion of other subatomic particles.
- Virtual photons do not carry charge, but allow particles with charge to exchange momentum.
Equations
Momentum of a Photon
\(p = \frac{h}{\lambda}\)
Where
\(p =\) The momentum of the photon.
\(h = \) Planck's Constant (\(6.63\times10^{-34}Js\)).
\(\lambda =\) The wavelength of the wave associated with the photon.
Energy of a Photon
\(E = hf\)
Where
\(E =\) The energy of the photon.
\(h = \) Planck's Constant (\(6.63\times10^{-34}Js\)).
\(f =\) The frequency of the wave associated with the photon.
The Speed of Light
\(c = f\lambda\)
Where
\(c =\) The speed of light (\(3.00\times10^{8}ms^{-1}\) in a vacuum).
\(\lambda =\) The wavelength of the wave associated with the photon.
\(f =\) The frequency of the wave associated with the photon.
Examples
This Feynman Diagram shows the electromagnetic interaction between two protons exchanging momentum via the virtual photon. | This Feynman Diagram shows the electromagnetic interaction between two electrons exchanging momentum via the virtual photon. |