Electromagnetic Devices (T)

• What is an electromagnet?

  It is a solenoid containing an iron core.
• What are the applications of electromagnets mentioned in the source?

  • Relay
  • Electric doorbell
• Why is it dangerous to use a switch in high-voltage circuits?

  Because they can cause sparking and pose a risk of electrocution.
• How does a relay function in a circuit?

  • Contains two separate circuits
  • Low-voltage circuit with an electromagnet
  • High-voltage circuit with metal contacts
  • Electromagnet creates a magnetic field to close contacts
• What occurs when the low-voltage circuit in a relay is switched off?

  The contacts spring apart, turning off the high-voltage circuit.
• What happens when the low-voltage circuit in a relay is switched on?

  The magnetic field attracts the iron block, closing the contacts and turning on the high-voltage circuit.
• How does an electric doorbell operate?

  • Switch is closed when the button is pressed
  • Current flows, producing a magnetic field
  • Iron contact is attracted, hitting the bell
  • Breaks the circuit, stopping the current
  • Iron contact springs back, completing the circuit again
• What is the sequence of events in an electric doorbell when the button is pressed?

  Current flows, magnetic field attracts the contact, hits the bell, breaks the circuit, and the contact returns.