Some science behind the scenes

Magnetic induction

Changes in an electric current or magnetic field can cause ("induce") changes in the other, according to Maxwell's equations and more particularly Faraday’s law.

Faraday's law describes how a time varying magnetic field creates ("induces") an electric field. This aspect of induction is the operating principle behind many electric generators: for example a rotating bar magnet creates a changing magnetic field, which in turn generates an electric field in a nearby wire.

A changing [pulsed] magnetic field will induce an electric field in anything that will conduct it.

There are a large number of sources of magnetic field but the two main ones are

  • Electrical instruments – both domestic and industrial.  Magnetic fields can be a by-product of use of  electrical instruments and electricity generation.  There are also some instruments that have been specifically designed to produce a magnetic field such as the Transcranial magnetic stimulator.