The Electric motor

The electric motor works because if a wire carrying an electric current is in a magnetic field there is a force on the wire. This makes the wire move if it can.

The diagram shows the view of a simple electric motor looking from the end of the axle. (The end of the axle is the small white circle in the middle of the diagram).
When a current flows through the coil there is a force on the coil. The side marked 1 is forced upwards and the side marked 2 is forced downwards.

The coil turns in an ANTICLOCKWISE DIRECTION. The inertia of the coil keeps it turning between each contact with the two input wires (+ and - ).

To make the motor turn faster we can:

(a) increase the current
(b) replace the magnets with more powerful ones
(c) push the magnets closer to the coil
(d) put an iron centre piece into the coil (this concentrates the magnetic field through the coil)
(e) adding more sets of coils around the central core

Changing the direction in which the motor turns

MAGNETS
If we change the magnets so that they face the other way (North on the left and south on the right) the motor will turn in the opposite direction (CLOCKWISE in this case).

CURRENT
If we change the direction of the current so that the wire on the right is negative and that on the left positive) the motor will turn in the opposite direction (CLOCKWISE in this case).

MAGNETS AND CURRENT
If we change BOTH the direction of the current AND the way the magnets are facing the motor will turn in the SAME direction as the original one (ANTICLOCKWISE in this case).

USING A.C.
Alternating current (a.c.) is current where the direction is changing all the time. It flows first one way and then the other. If our simple motor is connected to a.c. it will simply vibrate. It will start to turn one way and then immediately try and turn the other way as the current direction changes – result – vibration only.