Electromagnetic induction occurs whenever the magnetic field through a conductor changes. This can be due to a conductor moving through a magnetic field or a conductor being in a fixed position within a changing magnetic field, such as that due to an alternating current. Both of these result in an e.m.f. being induced in the conductor.Examples of electromagnetic induction include:
- moving a magnet inside a wire coil
- generating the high voltage necessary to ionise the vapour in a fluorescent tube and cause the spark needed to ignite the explosive mixture in a petrol engine
- changing the voltage of an alternating current, using a transformer.
The factors affecting the magnitude of the induced e.m.f includes;
1. The rate of relative motion between the conductor and the field – if the velocity of the conductor is increased the deflection in the conductor increases.
2. The strength of the magnetic field – a stronger magnetic field creates a bigger deflection
3. The length of the conductor – if the length is increased in the magnetic field the deflection increases.