4.2.6 electromagnetic induction

• electromagnetic induction - when a current is induced in a coil, a magnetic field is produced around the coil
• if a wire (or any electrical conductor) moves near a magnet, it induces a potential difference in the conductor
• A changing magnetic field is a magnetic field with changing strength
• If there is a magnetic field through the middle of a coil of wire, it is "linked" with the coil
• A changing magnetic field that is linked with a coil of wire induces a potential difference in that wire
• Current - rate of flow of charge
• We can induce more potential difference in an electrical conductor (coil of wire) during electromagnetic induction in two ways

  • more coils - increase number of turns of coils of wire
  • faster movement - making the magnetic field change more rapidly by moving the wire or the magnet more quickly
• In electromagnetic induction, the electrical conductor is the coil of wire.
• Electromagnetic induction

  A potential difference can be induced by:

  • Moving an electrical conductor in magnetic field
  • e.g. moving a wire between the poles of a horseshoe magnet induces a p.d in the wire.
  • A changing magnetic field “linking” with a coil of wire
  • e.g. moving a bar magnet in and out of a coil of wire induces a p.d in the solenoid.