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