# Homework Help: Why Do Accelerating Charges Generate Light?

1. May 24, 2010

### Creebe

1. The problem statement, all variables and given/known data
Why do accelerating charges generate light, whereas charges with constant velocities do not.

2. Relevant equations
No equations.

3. The attempt at a solution
A accelerating charge affects the E field and B field?

2. May 25, 2010

### Andrew Mason

I think you mean electro-magnetic radiation, not necessarily light.

If you are looking for a simple answer, it is because if you introduce a time-dependent electric field into Maxwell's equations, the solution is an equation for an electro-magnetic wave.

This does not explain, however, why a charge accelerating in a gravitational field does not produce an electromagnetic wave (according to General Relativity, such a charge is equivalent to a charge at rest in an inertial reference frame).

The key may be that that in order to produce an accelerating charge - other than by gravity- the charge has to interact with another charge somewhere in the universe (either through an em wave or an electric or magnetic field). So it may be the interaction with another charge that causes the resulting emission of radiation (and the acceleration).

The answer to this question, interestingly enough, is still not clear: See: http://www.mathpages.com/home/kmath528/kmath528.htm" [Broken].

AM

Last edited by a moderator: May 4, 2017