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  1. Describe the turning effect on a current-carrying coil in a magnetic field.

A coil in a magnetic field can be forced to turn by passing a curre.t through it.

When a current passes round the coil a force acts as shown on each of the two long sides of the coil. As these forces are in opposite directions, they act to make the coil turn.

This is called the motor effect.



  1. Relate this turning effect to the action of an electric motor

We learned from a.c. generator that a coil in a magnetic field connected to a circuit can produce electricity when it turns. The movement of the coil and the magnetic fields generate electricity; thus called a generator.

In a motor, the opposite happens, as described above. The current and magnetic fields produce the movement of the coil, and helps the motor function.

  1. Describe the effect of increasing:
    • the number of turns in the coil
    • the current.

When the number of turns in the coil increases or if the current is increased, the turning effect also increases, as in, more force is applied to the coil and so it turns faster.



Notes submitted by Lintha

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