The electric motor
Electric motors are found in many household devices e.g. tumble dryers, washing machines, vacuum cleaners, electric knives, food mixers, hair dryers and electric toothbrushes.
A coil of wire carrying a current in a magnetic field experiences a force that tends to make it rotate.
This effect can be utilised in an electric motor.
Explaining an electric motor
The diagram shows a simple motor using Direct current is the movement of charge through a conductor in one direction only..
Fleming’s left hand rule can be used to explain why the coil turns
Starting from the position shown in the diagram of the dc motor:
- current in the left-hand side of the coil causes a downward force, and current in the right hand side of the coil causes an upward force;
- the coil rotates anticlockwise because of the forces are in opposite directions;
- each side of the coil is now near the opposite magnetic pole.
The direction of rotation of the coil can be reversed by:
- reversing the direction of the current OR
- reversing the direction of the magnetic field (changing over the north and south poles).
The speed of rotation of the coil can be increased by:
- increasing the size of the current;
- using a stronger magnet;
- increasing the number of turns of wire in the coil;
- reducing A force that opposes or prevents movement. When work is done against friction, kinetic energy is converted into heat energy. between the coil and the axel it rotates on.