Concept preview

What you will be able to do

1. 01Describe magnetic fields and their sources
2. 02Apply $F = qvB$ and $F = BIL$ with the right-hand rule
3. 03Explain the circular motion of a charge in a magnetic field

Electric currents and intrinsic magnetic moments create magnetic fields. In a bar magnet, electron spin and orbital magnetic moments contribute; spin is an intrinsic quantum property, not a little charged sphere rotating. In an electromagnet, current in a wire creates the field. The magnetic field is a vector measured in teslas. Field lines outside a bar magnet run from its north pole to its south pole; cutting the magnet makes smaller dipoles, not isolated poles.