# Electric charge and magnets

1. Jan 23, 2016

### GuhaGubindam

I understand that a cathode ray will be attracted to one pole of a magnet, while being repelled away by the other. The cathode ray, being electrons and thus negatively charged, must definitely be attracted by the positive pole of the magnet, while being repelled by the negative pole of the magnet. In terms of north and south, which is positive and which is considered negative?

Last edited by a moderator: Jan 24, 2016
2. Jan 24, 2016

### UncertaintyAjay

There is no positive or negative with poles of a magnet. What happens is when you have a charged particle moving in a magnetic field B at a velocity v, a force acts on the particle. This force is given by F= q vxB. Here B, v and F are vectors. So the force is charge times the cross product of velocity and magnetic field.( Here is a link in case you don't know about cross products http://hyperphysics.phy-astr.gsu.edu/hbase/vvec.html) . So that gives you the direction of the field. Check out the link it'll tell you how to figure out the direction of the force. If you aren't familiar with vectors, read up on them because it's a very very important and useful thing to know.