electromagnetism

    Cards (8)

    • Relay
      A device that contains two separate circuits - a low-voltage circuit with an electromagnet, and a high-voltage circuit with metal contacts that are kept apart by a spring
    • How a relay works
      1. Low-voltage circuit is turned on, creating a magnetic field in the electromagnet
      2. Magnetic field attracts the iron block, causing the high-voltage contacts to close
      3. High-voltage circuit is now switched on
      4. When low-voltage circuit is turned off, no magnetic field, contacts spring apart, high-voltage circuit is switched off
    • Electric doorbell
      A device that uses an electromagnet to make a clapper hit a bell when the doorbell is pressed
    • How an electric doorbell works
      1. Switch is closed when doorbell is pressed
      2. Current flows through circuit, creating a magnetic field in the electromagnet
      3. Magnetic field attracts the iron contact, causing the clapper to hit the bell
      4. This breaks the circuit, stopping the current flow, and the iron contact springs back to its original position
    • Circuits using high-voltage switches can be dangerous, with risks of sparking and electrocution
    • Relays and electric doorbells use electromagnets to switch on and off high-voltage circuits in a safe way
    • A moving charge produces an electric current, which generates a magnetic field around it.
    • Electric charges can be positive or negative, while electric current is always considered as flowing from positive to negative.
    See similar decks