When a coil of wire carries an electric current in a magnetic field, it experiences a force that can cause the coil to rotate. This is how electric motors function.
The diagram below shows a simple DC electric motor.
We use a coil of wire that is free to rotate between two opposite magnetic poles.
Each end of the coil is connected to a split ring commutator. Each side of the commutator is connected to the opposite poles of a direct current (DC) power supply.
1. The flowing current will create a magnetic field around the coil.
2. The magnetic field produced by the current will interact with the magnetic field produced by the permanent magnets.
3. As a result, a force is exerted on the coil.
4. The magnetic field will produce an upward force on one side of the coil and a downward force on the other side. This causes the coil to rotate.
5. The coil will continue to rotate until it reaches a vertical position.
6. A split ring commutator changes the direction of current every 180°, which ensures that the torque continues in the same direction.
7. Although the different sides of the coil are in opposite locations after a half spin, the reversed current keeps the coil in rotation.