- Procedure: Hold the magnet-drill assembly close to the balanced disc and operate the drill. The magnet exerts a torque (via eddy currents) on the disc, causing it to spin in the same direction as the magnet. The disk can be brought up to high speed very very quickly.
- This demonstrates one method used in speedometers.
- There is also a second disk made of the same material that has slits cut along it to eliminate eddy currents from forming.
- For best results, remove the aluminum disc from the magnet, oil the base at the contact point, and hold the magnet very close to the disc.