Active learning ideas
The motor effect is the culmination of the study of magnetism and electricity. It occurs when a current-carrying wire is placed in an external magnetic field, resulting in a force that moves the wire. Students learn to use Fleming's Left-Hand Rule to predict the direction of this force based on the directions of the magnetic field and the current. This is a high-level skill that requires spatial reasoning and precision.
Activity 01
Create a large floor grid with 'Current' and 'Field' directions. Students must use their left hand to correctly orient themselves to the 'Force' direction called out by the teacher, checking their partners' form.
What is the motor effect?
Activity 02
Groups are given a battery, a magnet, and a coil of wire. They must assemble a working motor and then experiment with reversing the battery or the magnet to see how it affects the direction of rotation.
How do we use Fleming's left-hand rule?
Activity 03
Students look at a diagram of a motor without a commutator. They must discuss why the coil would just flip back and forth rather than spinning, then explain how the split-ring solves this problem.
How does a simple d.c. motor function?
Templates
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A few notes on teaching this unit
Watch Out for These Misconceptions
The force is always in the same direction as the current.
Students often struggle with the 3D nature of the motor effect. Using physical 3D axes (like pencils taped together) helps them visualise that the force, field, and current are all at right angles to each other.
Any wire in a magnetic field will experience a force.
Clarify that if the wire is parallel to the field lines, there is no force. A 'find the force' gallery walk with different wire orientations helps students identify when the motor effect will and won't occur.
Methods used in this brief
Permanent and Induced Magnetism
A study of magnetic poles, magnetic fields, and the difference between permanent and induced magnets. Students will map magnetic fields using compasses.
8 methodologies
Electromagnetism
Students investigate how electric currents produce magnetic fields and how solenoids enhance this effect. The topic covers the construction and uses of electromagnets.
8 methodologies