Changing Fields

To begin, students induce EMF in a coil of wire using magnetic fields. Then, demonstrations on eddy currents show how a magnetic field can slow magnets just as eddy currents are used to slow large trains. Then students observe a demonstration in which a loop "jumps" because of a changing magnetic field. Finally, a lecture reviews the cross product with respect to magnetic force and introduces magnetic flux, Faraday's law of Induction, Lenz's law, eddy currents, motional EMF and Induced EMF.