4-ELM-04

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Specification References

  • 6.15 recall that a voltage is induced in a conductor or a coil when it moves through a magnetic field or when a magnetic field changes through it; also recall the factors which affect the size of the induced voltage.
  • 6.16 describe the generation of electricity by the rotation of a magnet within a coil of wire and a coil of wire within a magnetic field; also describe the factors which affect the size of the induced voltage.

Starter

  • recall that field lines flow from the North pole to the South pole.
  • show students that you don't use a power supply, but when you move a wire up and down between two poles of a magnet, current will be recorded by a miliammeter.

Main Body of Lesson

  • have a short 'brain storm' trying to explain how current appears in the circuit you have just shown them
  • emphasize the fact that a power supply is NOT used and movements of the wire in between the two poles of the magnet have an important role.
  • Anytime filed lines are cut, current is recorded by the ammeter
  • If the wire is kept still in between the two poles of the magnet, no current is recorded, so there should a direct correlation between movements of the wire and recorded current.
  • Whenever the wire moves, it CUTS the field lines and current is induced. This is Electromagnetic induction.
  • The current induced due to electromagnetic induction is alternating current (a.c.)

Plenary

  • Demonstrate electromagnetic induction using all other demos and encourage students to explain, step by step, how current is induced in each case.
  • Discuss about the vast usage of electromagnetic induction: dynamos, generators.
  • Use and discuss the ‘a.c.generator’ worksheet (Science Shared)

Homework

  • students to write about the differences and similarities between the ‘electric motor’ and the ‘a.c. generator

Additional Information

Resources Required

  • electromagnetic induction demos

Textbook References

  • None

Website References

  • None

Skills Addressed

Safety/Hazards

Notes

  • None