loudspeakers and headphones

• Moving coil loudspeaker


  • Cone
  • Coil of wire wrapped around one end of the cone
  • Permanent magnet inside the coil of wire
• How a moving coil loudspeaker works

  1. Current passes through the coil, generating a magnetic field

  2. Magnetic field from the coil interacts with the magnetic field from the permanent magnet

  3. Magnetic fields either attract or repel, producing a resultant force that causes the cone to move in and out

  4. Changing the frequency of the AC supply changes the frequency that the cone vibrates, producing different pitches of sound

  5. Increasing the size of the current increases the amplitude of the vibration, increasing the volume of the sound
• When the cone switches direction


  The direction of the force on the cone reverses
• Moving coil loudspeakers are also found in headphones, but on a smaller scale