loudspeakers

• loudspeakers use the motor effect to convert variations in current in electrical circuits to pressure variations in sound waves (convert electrical signals into vibrations which then generates sound waves)
• • a loud speaker consists of a coil of wire which is wrapped around one pole of a permanent magnet, and connected to a cone
  • the coil of wire is permanently attached to the cone, but the coil and cone can slide back and forth along the magnet
• loudspeakers:

  1. an alternating current flows through the wire and creates a magnetic field in the coil
  2. the magnetic field of the coil interacts with the magnetic field of the magnet
  3. the interacting magnetic fields will exert a force on the coil (motor effect) causing it to move back and forth along the permanent magnet
  4. meaning the cone to change shape
  5. as current is alternating, the magnetic field and force experienced is also alternating. This means that the coil of wire and cone rapidly move back and forth, meaning they vibrate
  6. vibrations in the cone cause pressure variations in the air