if an electrical conductor moves relative to a magnetic field or if there's a change in the magnetic field around a conductor, a potential difference is induced across the ends of the conductor - if the conductor is part of a complete circuit, a current is induced in the conductor
an induced current generates a magnetic field that opposes the original change, either the movement of the conductor or the change in magnetic field
the generstor effect is used in an alternator to generate AC and in a dynamo to generate DC
microphones use the generator effect to convert the pressure variations in sound waves into variations in current in electrical circuits
what does a basic transformer consist of
a primary coil and a secondary coil wound on an iron core (iron is used as its easily magnetised)
the ratio of the potential differences across the primary and secondary coils of a transformer (Vp and Vs) depends on ratio of the number of turns on each coil (np and ns)
Vp / Vs = np / ns
in a step up transformer, Vs > Vp
in a step down transformer, Vs < Vp
if transformers were 100% efficient, the electrical power output would equal the electrical power input
