How does Faraday's Law of Induction work?

Question

I really want to learn it but wikipedia is a little much. Can someone give me a run through?

Answer 1

Faraday's law says that any change in the amount of magnetic flux passing through a given surface will result in the creation (called induction) of an electromotive force (voltage) which will have the effect of generating a current that will act to cancel out the change in magnetic flux.  

So, any time you have a changing magnetic field -- which could be someone moving a bar magnet, or someone turning an electromagnet on or off -- you will induce a voltage, and voltages generate currents (which generate magnetic fields).

Answer 2

Faraday's law simply says that a changing magnetic field induces a voltage in a conductor.

Suppose you have a bar magnet with some wire wrapped around it. While the magnet stays still, there will be no voltage induced in the wire. Now pull the magnet out. A voltage will be induced in the wire as the magnet moves. The faster you move the magnet, the larger the voltage.

Here's another example. An electric guitar pickup consists of some magnets with a lot of thin wire wound round them. The guitar strings are in the magnetic field of the pickup. When the strings are plucked, the magnetic field changes -- the strings are made of steel, which is ferromagnetic -- and this changing field induces a voltage in the coil, which can be fed to an amplifier.

Faraday's law is the basis of electrical generators such as dynamos and alternators, as well as transducers such as magnetic pickups and dynamic microphones. It's also the basis of the transformer.

In symbols, v = N (dphi / dt), where v is voltage, N is the number of turns, and dphi / dt is the rate-of-change of magnetic flux, phi.