microphones and transformers

• a moving coil microphone uses the generator effect to convert sound waves to electrical signals
• 1. the sound waves hit the microphone
  2. the changes in the pressure related to the sound wave cause the microphone diaphram to oscillate
  3. the microphone diaphram and coil vibrate at the same frequency as the incoming sound wave
  4. this induces a potential difference and current in the coil with the same frequency as the incoming sound wave and an amplitude dependant on the amplitude of the incoming wave
• a basic transformer consists of a primrary and secondary coil wrapped around a soft iron core
• transformers

  • an alternating current flows through a primrary coil , which is effectivley a solenoid
  • this alternating current induces an alternating magnetic field
  • the alternating magnetic field in the iron core induces an alternating difference in the secondary coil
  • if the secondary coil is part of a complete ciruit , an alternating current flows in the secondary coil
• if the transformers were 100 % efficient , the power output would be the same as the power input
• power = current × voltage

  • so when potential difference is increased , the current is reduced