electromagnetic devices

• An electromagnet is a solenoid containing an iron core
• Electromagnets are found in many appliances
• A relay contains two separate circuits: a low-voltage circuit with an electromagnet, and a high-voltage circuit with metal contacts
• How a relay works

  1. Low-voltage circuit is turned off, no current flows through electromagnet, no magnetic field, high-voltage contacts are open

  2. Low-voltage circuit is turned on, current flows through electromagnet, magnetic field is produced, magnetic field attracts iron block, high-voltage contacts close, high-voltage circuit is turned on

  3. Low-voltage circuit is turned off, no magnetic field, high-voltage contacts spring apart, high-voltage circuit is turned off
• Relays allow safe switching of high-voltage circuits
• An electric doorbell contains an electromagnet
• How an electric doorbell works

  Switch is closed when buzzer is pressed, current flows through circuit, electromagnet produces magnetic field, iron contact is attracted to magnetic field, clapper hits bell, circuit is broken, no current flows, no magnetic field, iron contact springs back, circuit is complete again
• Electromagnets are used in many devices