Electromagnetism

Electric Motor.

Electric motors have a wide variety of uses.

The catapult effect (motor effect) is used to make a simple electric motor.
The wire is pushed in the opposite direction
if the direction of the current through it is reversed.

In a motor, the wire is wound around a central block called an armature.
A spindle through the armature allows it to rotate.
The current flows in opposite directions on each side of the armature,
so one side is pushed while the other is pulled.
This makes the armature rotate.

Forces on a Spinning Motor

After the armature has rotated through half a turn (180°),
then the side of the armature being pushed upwards in the above picture
is now on the left and the side being pulled down on the right.
The armature would be trying to turn in the opposite direction.

For the armature to continue to spin in the same direction,
the direction of the current flowing through the wire
must be reversed every half turn.
This is achieved using a split - ring commutator (see next page).