Copyright © 2007 Dorling Kindersley
Electric motors make things move. They convert electrical power into mechanical power using electromagnetic attraction and repulsion. There are many kinds of electric motor. Small motors can run on batteries to power toys. Larger motors use mains electricity to work kitchen gadgets. Factories use even bigger motors to power heavy machines. Trains and trams also use electric motors to push them along without smoke or noise.
Japanese Shinkansen (“bullet”) trains, which can travel at 300 kph (187 mph), use electric motors. Electric motors are ideal for trains. As well as being clean and quiet, they can be placed all along the train instead of at just one end, as in a diesel locomotive. This helps the train get up to speed more quickly. The motors can also help slow it down, by acting as generators and turning motion back into electricity.
Tesla devised the motor most often used in factories. The rotor needs no electrical connection, so the motor is more reliable. To power the motor, Tesla invented a generator that produces three currents. These combine to create a rotating magnetic field that pushes the rotor around.