generators

• alternators

  • generators rotate coil in a magnetic field
  • as coil spins current is induces
  • current changes direction every half turn to create potential difference
• dynamos

  • same as alternators but they have split ring commutators
  • swaps connection to keep current in the same direction
• microphones

  • loudspeakers in reverse
  • sound waves hit diaphragm attatched to coil or wire
  • coil moves - generates current
  • pressure variations turn into current