Motors + Loudspeakers

• Direct current = current flows in 1 direction
• Alternating current = current flows in 2 directions
• A motor uses the motor effect to spin generator

  
• A motor

  1. Current carrying wire sits between 2 opposite poles of a magnet
  2. Each side of the wire experiences a force in opposite directions
  3. Because the coil in on a spindle, and the forces are in opposite directions, it spins
  4. The split ring commutator swaps the contacts every half turn to keep the motor spinning in the same direction
• How can I swap which way my motor spins?

  • Swap the poles
  • Swap the direction of current
• To speed up a motor

  • Increase the current
  • Add more turns to the coil
  • Increase the magnetic flux density (field strength)
• A loudspeaker is the opposite of a microphone
• Loudspeaker

  1. Coil of wire with an iron core surrounded by a magnetic field
  2. Alternating current electrical signals are fed to the coil of wire, which is wrapped around the base of the cone
  3. The interaction between the magnetic field and the current cause the coil to move in one direction
  4. However the alternating current means that the coils experiences a force in the opposite direction aswell, causing it to vibrate
  5. These vibrations create sound