25.2. Using Electromagnetism http://www.ck12.org
FIGURE 25.6
An electromagnet uses a solenoid and an iron bar to create a very strong magnetic field.Electromagnetic Devices
Many common electric devices contain electromagnets. Some examples include hair dryers, fans, CD players,
telephones, and doorbells. Most electric devices that have moving parts contain electric motors. You can read below
how doorbells and electric motors use electromagnets.
How a Doorbell Works
Figure25.7 shows a diagram of a simple doorbell. Like most doorbells, it has a button located by the front door.
Pressing the button causes two electric contacts to come together and complete an electric circuit. In other words,
the button is a switch. The circuit is also connected to a voltage source, an electromagnet, and the clapper of a
bell. When current flows through the circuit, the electromagnet turns on, and its magnetic field attracts the clapper.
This causes the clapper to hit the bell, making it ring. Because the clapper is part of the circuit, when it moves to
strike the bell, it breaks the circuit. Without current flowing through the circuit, the electromagnet turns off. The
clapper returns to its original position, which closes the circuit again and turns the electromagnet back on. The