5G20.10-Barkhausen Effect

Video: Watch this demo

Description: A change in the magnetization of a ferromagnetic material induces a sound into an amplifier


  • 3200 turn coil
  • Medium neodymium magnet
  • Operational amplifier
  • Speaker
  • Long steel nail
  • Plastic rod
  • Wires


  1. Connect the speaker to the amplifier, and the amplifier to the coil
  2. Set the gain on the amplifier to the maximum value, and the DC offset to 0
  3. Turn the speaker and amplifier on; adjust the volume as necessary on the speaker
  4. Slide the plastic rod through the coil and wave the magnet right over the coil; no sound should be produced
  5. Replace the plastic rod with the steel nail, and wave the magnet right over the coil; a shaking sound come out