Motor
CD players spin their CDs with an electric motor, and that electric motor uses magnets. A rotor with several magnets on it is surrounded by coils of wire, which serves as electromagnets. When electricity is run through one of these electromagnets, it becomes magnetized until the electricity is turned off. This pules pulls on the magnets on the rotor, making the rotor turn. As a magnet passes an electromagnet, that electromagnet turns off and the next one turns on, continuously tugging the rotor around in a circle at a constant rate.
Tracking Mechanism
The CD player tracking mechanism also uses magnets. The tracking mechanism is a device which moves the lens along the CD, tracking the grooves. It uses a very slow, precise electric motor called a stepper motor to control it. The stepper motor is called that because every rotation can be divided into several steps. By controlling which electromagnets it turns on and off, the stepper motor can keep the lens focused on the groove in the CD.
Relay
Most CD players use electromagnetic switches called relays. Have you ever turned on the power on your CD player or another appliance, and heard a click immediately before it went on? That's a relay doing its job. In a relay, a small current runs through a coil which is right next to a switch with a magnet in it. The coil pulls on the switch, closing it and turning on the device. Relays are useful because they use a small current to control a much larger one. As a result, they are often used in the power supplies of electronic devices such as CD Players
Tags: electric motor, stepper motor, magnets rotor, motor called, small current, uses magnets