# Homework Help: Circular Polarisation vectors

1. May 3, 2010

### hhhmortal

1. The problem statement, all variables and given/known data

A particle of charge 'q' and energy 'E' which experiences an acceleration 'a', emits electromagnetic radiation.

Show that the radiation from this particle which is emitted parallel to the magnetic field is expected to exhibit circular polarisation.

3. The attempt at a solution

I started by saying the cross product of external B with B component of the radiation are perpendicular (i.e. 90°) and because of this the radiation will be circular polarised.

But this answer seems to be very simple..

2. May 4, 2010

### nickjer

Circular polarization means the E and B fields are rotating. You never mentioned in your explanation anything about rotation. Also you really need to explain the problem better or show a picture.

Right now I am assuming this is a charged particle travelling in a circle due to a magnetic field in the z-direction. Also knowing the direction of the acceleration vector, you can find the directions of E and B, and show they are circularly polarized and transverse to the z-axis in the far-field. This is assuming I have the right picture.

Last edited: May 4, 2010
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