## 2009-01-14

### Induced Current and Induced Electromotive Force

The production of an electric current by a changing magnetic field is called electromagnetic induction.

The induced current is produced only when there is a relative motion between the conductor/coil and the magnetic field lines.

The induced current is produced when:
a)a conductor cuts across a magnetic flux.
b)there is a change of magnetic flux linkin  a coil or a circuit.

Relative motion

1. There is a relative motion between two objects if the two objects are getting closer or further apart.
2. When two objects are moving at the same speed in the same direction, there is no rleative motion because the distance between the two object does not change.

Induced current and Induced Electomotive Force

1. The electromotive force is required to drive the current in  a closed circuit.
2. Induced electromotive force is produced between the ends of the moving conductor or the solenoid.
3. When a galvanometer is connected to form a closed circuit, the pointer of the galvanometer moves when the magnet is directed back and forth inside the solenoid.
4. The induced e.m.f is responsible for driving the current flowing the closed circuit through the galvanometer. The greater the induced e.m.f., the greater the induced current.
5. The magnitude of the induced e.m.f and direction of the induced current can be determined by application of the laws of electromagnetic induction.