Arago's disc (rotational magnetism)
Disco de Arago (magnetismo de rotación)
- Date
- 1824 · confidence high
- Place
- Paris, France
- Credited to
- François Arago
- Field
- Matter & energy
What was discovered
Arago observed that a spinning copper disc drags a magnetised needle held above it, although copper is not magnetic. It was the first effect of induced currents, which Faraday explained in 1831.
What it led to
- Faraday's electromagnetic induction (1831)
- eddy-current braking
- induction meters and speedometers