How much protection you need, though, is a different story. The magnetic field produced by a microwave oven from an inch away, for example, is only about two gauss. Power tools, from the same distance ...

Electricity and magnetism including Coulomb's Law, electric field, Gauss' Law, electric potential, Ohm's law, DC circuits with resistors, magnetic field, Ampere's Law, Faraday's Law, inductance, ...