Electricity and Magnetism

Electromagnetic devices

Classroom Activity for 11-14 Supporting Physics Teaching

What the Activity is for

Electromagnetic machines are very common. The aim of this activity is to make clear how a small selection of these work, drawing on the behaviour of electromagnets that pupils have seen.

What to Prepare

  • a mounted relay with power supplies, switch and lamp (You should aim to have a mounted demonstration relay with the two circuits quite separate, and run from two separate power supplies, with one small (for the low current circuit), and one large (for the high current circuit which might conveniently drive a large lamp.)
  • a mounted bell (The mounted bell should display as much of the mechanism as possible.)
  • a video camera to provide an enlarged display of the demonstration
  • two interactive objects

What Happens During this Activity

Show the bell in action, focusing on the make and break switch inside the bell. Use the interactive object to review the pupils understanding. You could also reverse this order, talking through the interactive object yourself, then showing the real bell.

Show the relay in action, focusing on the two separate circuits and the magnetic link between them. Use the interactive object to review the pupils' understanding. You might call pupils to the front to provide a commentary for each stage.


Download the interactive objects for this activity.

can be analysed using Magnetic Field
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