Electromagnetic induction is the phenomenon of using a magnet to create, or induce, a magnetic field in a conductor while simultaneously dislodging free electrons within it. This produces a flow of current and a rising and collapsing magnetic field around the conductor, which is the opposite polarity to that of the magnet from which it was induced.
Electromagnetic induction makes use of the chemical properties of certain materials known as conductors. Conductors have free electrons, which are electrons loosely bound to the outer shell of their host atoms. These electrons, when dislodged, flow through the conductor, resulting in electrical current. While the induced current is important and extremely useful by itself, electromagnetic induction has many other uses as well.
Induction is in use in many forms and applications, from computer chips to doorbells. The induced magnetic field is used to close circuits, such as with relays, and it is also used for timing. The length of time that a given electromagnetic field takes to rise and fall in strength is easily predicted, making it a very common timing tool in a wide range of electronic components. Electromagnetic induction is produced either by moving a magnet through a coil of wire on a substrate or by moving coils of wire passed stationary magnets. The latter design is much more practical and more common, as conductors are typically easier to manipulate and easier to move than are powerful, heavy magnets.