Uses of magnetism

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Question 9
Medium

A student investigates a simple electric motor as shown in the diagram below.

A diagram of a simple direct current (DC) motor setup. A rectangular coil of wire is suspended horizontally between the curved poles of two permanent magnets along a central dashed axis of rotation. The magnetic pole on the left is labeled 'S' (South) and the magnetic pole on the right is labeled 'N' (North). The ends of the coil connect to a split-ring commutator. Brushes on either side connect the commutator to an external DC circuit. An arrow in the circuit on the right side is labeled 'Direction of current' and points upwards towards the right brush, so current enters the right half of the commutator. On the coil, an arrow points away from the viewer on the right side, and another arrow points towards the viewer on the left side.

a.

Explain why the coil experiences a turning force when a current flows through it.

[3]
b.

In which direction will this motor turn? State the name of the rule you used to work this out.

Direction: …………\dots\dots\dots\dots…………

Name of rule: …………\dots\dots\dots\dots…………

[2]
c.

Suggest two modifications that would increase the size of the force on the coil.

[3]

Uses of magnetism Questions

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