A charged particle such as an electron, is deflected by
a magnetic field. The direction and magnitude of the force
**F**,
on the electron is given by the vector equation:

**F**
= e(**v** ´ **B**)

**v**
is the instantaneous electron velocity

B is the magnetic field

e is the
charge

The force acts perpendicular to the field and velocity.
This causes the particle to move in a circle. This is animated
opposite by clicking on the start button.

In the diagram **v**
shows the initial velocity of the electron, so the initial
force is downwards, resulting in a circular path around
the magnetic field line