Generators and Microphones

• Alternators generate alternating current

  • They rotate a coil in a magnetic field
  • As the coil spins, a current is induced in the coil, this changes direction every half turn
  • Instead of a split-ring commutator ac generators have slip rings and brushes so the contacts dont swap every half turn
  • This means they produce an alternating current
• Dynamos

  • Have split ring commutators
  • This swaps the connection every half turn to keep the current flowing in the same direction
• Microphones

  • Soundwaves hit a flexible diaphragm that is attached to a coil of wire, wrapped around a magnet
  • This causes the coil of wire to move in the magnetic field, which generates a current
  • The movement of coil depends on the properties of the sound wave
  • This is how microphones convert pressure variations into variations in current