Electromagnetic Induction

• Faraday's Law

  The magnitude of induced emf is equal to the rate of change of flux linkage
• Lenz's Law

  The direction of any current resulting from an induced emf is such as to oppose the change in flux linkage causing the current.

  For an emf to give rise to a current, the circuit must be closed.

  The induced magnetic field opposes the motion of a magnet through a solenoid.
• Consequences of Lenz's Law

  • When the circuit is closed, a voltage is created
  • If a magnet is dropped through a solenoid, the magnet falls at a slower rate than gravity
• When a magnet approaches a solenoid, the two poles oppose each other
• When a magnet moves away from a solenoid, the two poles attract each other