Physics Form 5: Chapter 3 - Electromagnetic Induction

• Electromagnetic induction is the production of an electromagnetic force, (e.m.f)   in a conductor by changing magnetic field.

• Each time the straight wire cuts across the magnetic field or the permanent magnet moves towards the solenoid, a current is induced in the coil and a deflection is observed in the sensitive galvanometer.
• An induced e.m.f  is produced in a conductor if the conductor is in a changing magnetic field.

Faraday's Law states that the magnitude of the e.m.f induced in a conductor is directly proportional to the rate of change of the magnetic field.

Click on the diagram below to play!

Lenz’s law states that the induced current always flows in the direction in such a way that it opposes the change that produces it.

• When the S pole of a magnet moves towards end of a solenoid, the end will become a magnetic S pole to oppose the motion of the magnet.
• When the N pole is pulled away from end of the solenoid, the end will become a magnetic S pole so as to oppose the motion of the magnet.
• Lenz’s law is based on the principle of conservation of energy. The work done in moving the magnet is converted to electrical energy.

Click on the diagram below to play!