Video: Watch this demo
Description: A change in the magnetization of a ferromagnetic material induces a sound into an amplifier
Equipment:
- 3200 turn coil
- Medium neodymium magnet
- Operational amplifier
- Speaker
- Long steel nail
- Plastic rod
- Wires
Procedure:
- Connect the speaker to the amplifier, and the amplifier to the coil
- Set the gain on the amplifier to the maximum value, and the DC offset to 0
- Turn the speaker and amplifier on; adjust the volume as necessary on the speaker
- Slide the plastic rod through the coil and wave the magnet right over the coil; no sound should be produced
- Replace the plastic rod with the steel nail, and wave the magnet right over the coil; a shaking sound come out
