The Motor Effect!
Summary: Electric currents in wires and coils produce magnetic fields. If these wires and coils are near strong permanent magnets, the wires and coils can actually start to move. This movement is caused by the interaction between two magnetic fields. The first field is the magnetic field produced when the current flows in the wires and coils, the second is the magnetic field from the permanent magnet. This combination of electricity and magnetism which causes movement is called the motor effect. This is how electric motors create movement. When a motor operates, electrical energy is transformed into kinetic (movement) energy. The motor effect occurs when a conductor carrying an electric current is placed in a magnetic field. The conductor experiences a force and, if this force is large enough, the conductor will move.
What’s inside an electric motor?:
Coil
Armature
Permanent magnets
Commutator
Brushes
Steel former
How does it work?: The motor is connected to a battery. When the switch is closed, the current starts to flow and the coil becomes an electromagnet. In this case the current is flowing anticlockwise in the top of the coil. This makes the top a north pole. This north pole is attracted to the south pole on the left. So the top of the coil turns towards the left. Notice that the bottom of the coil is a south pole and is attracted to the magnet on the right. Once the coil gets to the upright position, there is no turning force on it because the electromagnet of the coil is lined up with the permanent magnets. If the current in the coil were constant, the coil would stop in this position. However, to keep it spinning, the commutator breaks contact in this position. So the current stops for an instant. The momentum of the coil keeps it going and the contacts are reconnected. However, they are now the other way around. So, the side of the coil that used to be a south pole is now a north pole. The commutator will keep...