Inducing EMFs
When a conductor moves at right angles through a magnetic field an emf or voltage is created across it. This is because the charged particles in the conductor experience a force as they move, so they migrate to one end of the conductor resulting in a voltage.

To produce an emf we need:

A magnetic field        A conductor         Relative movement

If there is a complete circuit the a current will also be induced.

The size of the emf depends on the strength of the field, the length of the conductor and the speed of the relative movement.

Faraday's law tells us that;

which, in S.I. units conveniently boils down to

In words, the induced emf is proportional to the rate of change of flux, or the rate of flux cutting.

The amount of flux cut per second ( Wb/s ) is equal to the voltage produced.

In the case of a log straight conductor moving at right angles to a uniform field the emf can be shown to equal;

E = B l v    where B = field strength, l = length of conductor and v = velocity

A generator consists of a coil rotating in a magnetic field.