# Why photon with no charge produces force on charges?

1. Mar 29, 2008

### wudingbin

why photon has no charge though it is produced by either proton and electron, which are both charged??

2. Mar 29, 2008

### CompuChip

What is the charge of a proton?
What is the charge of an electron?
What is their total charge?

By the way, is this reaction ($p^+ + e^- \to \cdots \gamma$) even allowed?

Last edited: Mar 29, 2008
3. Mar 29, 2008

### neu

Either .... and .... does not make sense.

Do you mean photon emission by the transition of an atomic electron?

4. Mar 29, 2008

### Danger

As far as I understand particle physics, a photon is a bosun. As such, it transfers a charge from one place to another, but doesn't have one of its own.

5. Mar 29, 2008

### neu

No, Bosons can have charge, e.g. W+/-.

Bosons are just integer spin particles, they can be massive, massless, charged neutral ...

The photon is a massless boson which couples to electric charge and as such mediates the electromagnetic force.

A photon can be produced by a charged particle if it is energetically favourable, that is if the particle has sufficient energy to emit a real photon, or if a photon can be emitted and absorbed within the time permitted by the uncertainty principle (a virtual photon).

So an electron can emit a photon, for example when traversing matter at high energy and being decelerated by the electric fields of the atoms of the medium, or when changing energy level in an atom, or in annihilation with it's antiparticle etc etc.

It doesn't loose its charge (except in annihilation where all charge is destroyed).

Last edited: Mar 29, 2008
6. Mar 29, 2008

### Danger

Okay, I knew that a photon can be emitted by an electron reverting to ground state, but I didn't realize that it could take the negative charge with it when it left.

7. Mar 29, 2008

### neu

No, I didn't say that, at least I didn't mean to. A photon is always neutral, it couples to electric charge i.e. it can only interact with charged particles but it itself is never charged. Never

The electron retains its charge throughout, the photon only gains energy

8. Mar 29, 2008

### wudingbin

how to interact with charged particles, if photon contain no charge?
as we all know photon have electric and magnetic components.
so, where to the charge in the electric component go to???