Реферат: Electric motors

A machine that converts mechanical energy into electrical energy is called a generator, or dynamo, and a machine that converts electrical energy into mechanical energy is called a motor. So, a motor takes electricity and turns it into energy that can be used by us. Two related physical principles underlie the operation of generators and motors. The first is the principle of electromagnetic induction discovered by the British scientist Michael Faraday in 1831. If a conductor is moved through a magnetic field, or if the strength of the magnetic field acting on a stationary conducting loop varies, a current is set up or induced in the conductor. The converse of this principle was first observed by the French physicist Andre Marie Ampere in 1820. If a current is passed through a conductor located in magnetic field, the field exerts a mechanical force on it. An electric motor has to use magnetism and electric currents to work. There are two different kinds of motors, Alternate current (AC) and Direct Current (DC) Motors. They differ from each other only in using two different kinds of energy. The Alternate Current (AC) motor was introduced by Nikola Tesla in 1887. Up to that time direct current had been used by all other motors. Now, alternate current motors are easier to use than direct current ones. Motors are used everywhere. They are used in cars and many household appliances.