# Calculation of EM Wavelength

1. May 13, 2008

### Usaf Moji

So, accelerating charges produce EM waves, and I understand that the greater the acceleration, the shorter the wavelength of the EM waves. It is also my understanding that when one charge is attracted to another, EM waves are somehow exchanged between the two.

Now, let's say you have a unit charge of small mass accelerating towards another (opposite) unit charge of very large mass (i.e. so that the small mass moves while the big mass stays essentially stationary), and let's say we know what the acceleration of the small mass is at various points along its path. I have two questions:

1) In which direction does the exchanged EM wave propagate? i.e. is it towards the big mass, towards the small mass, or both? If both, does the net EM field cancel (i.e. is the field equal but opposite)?

2) How can I calculate the wavelength of the EM wave at the points where the acceleration of the small mass is known?

All responses appreciated.