An electric motor uses a current and a magnetic field to create motion. A specially shaped coil of wire, called an armature, is positioned between the poles of a permanent magnet. When an electric current is fed into the wire, the coil becomes a magnet too and forces of attraction and repulsion between it and the permanent magnet cause the armature to move around its axis. A device called a commentator then reverses the current, so that the armature’s magnetic poles are reversed and it turns through 180 degrees. If the current is continually reversed, the armature is always turning on its axis. It is this motion that can be used to drive a huge number of machines, such as washing machines, hairdryers and food processors.
An electric motor creates rotational, or circular, motion. The central part of the motor is a cylinder called the armature or rotor. The armature holds the rest of the components and is also the part of the motor that spins. Around the armature is the stator, which holds insulated coils of wire, usually copper. When a current is applied to the motor, the stator generates the magnetic field that drives the armature. Depending on the design of the motor, you might also find brushes, or fine metal fibers that keep current running to the opposite side of the motor as it spins.
The basic motor runs on DC, or direct current, but other motors can run on AC, or alternating current. Batteries produce direct current, while the outlets in your home supply alternating. In order for a motor to run on AC, it requires two winding magnets that don’t touch. They move the motor through a phenomenon known as induction. These induction motors are brushless, since they don’t require the physical contact that the brush provides. Some DC motors are also brushless and instead use a switch that changes the polarity of the magnetic field to keep the motor running. Universal motors are induction motors that can use either source of power.
Now that you have the basic parts and principles, you can play with the concept at home. Make a coil from lower gauge copper wire and poke each end through an aluminum can to suspend it. Place a small, strong magnet on either side of the suspended coil to create a magnetic field. If you attach a battery to both cans using alligator clips, your coil will become an electromagnet and the copper wire rotor you created should start to spin.