A magnetic field can cause charges (e−, p+, or ions) to move due to a magnetic force, denoted by . We usually figure out the magnitude and the direction of the force separately.
For point charges, the magnitude of the magnetic force is
where is the charge in coulombs (C), is the speed of the particle in metres per second (m/s), is the magnetic field in teslas (T), and is the angle between the conventional current and the magnetic field.
To get the direction, we once again use the right-hand rule. Your fingers (flat, not curled) point in the direction of the magnetic field (the north pole being at your finger tips); your thumb points in the direction of the conventional current (positive to negative—if it’s an electron that’s moving, the current is in the direction opposite to the particle velocity); and your palm, if you imagine that there is an arrow perpendicular to it going out from the centre, represents the magnetic force.
It works a bit differently for conductors. We get the magnitude of the magnetic force for straight conductors with
where and are the same as before, and where is the current in amperes (A) and is the length of the conductor inside the magnetic field in metres (m). The right-hand rule works the same way that it does for point charges.