Generators and Microphones

• How do alternators generate and alternating current?

  • alternators rotate a coil in a magnetic field
  • their construction is similar to a motor
  • as the coil spins, a current is induced in the coil, this current changes direction every half turn
  • instead of a split-ring commutator, ac generators have slip rings and brushes so the contacts don't swap every half turn
  • this means they produce an alternating potential difference
• How do dynamos work to create direct current?

  • same way as alternators
  • but have a split-ring commutator instead of slip rings
  • this swaps the connection every half turn to keep the current flowing in the same direction
• What does an oscilloscope show?

  How Potential difference generate in the cil changes over time
• How do microphones work?

  • sound waves 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 the coil depends on the properties of the the sound wave
  • this is how microphone can convert the pressure variations of a sound wave into variations in current in an electric circuit