Post #2988149
2026-05-14 14:45 UTC
This is the classical way in which I've always showed the experiment, even if with a self-made coil with less windings.
This perfectly shows the Faraday induction law, however not in the way Faraday discovered it as he was using not such a strong magnet, but a primary coil with currents, instead.
(it is good however to see such a clear induction here, because this primary coil has approximately N=10,000 windings, and the effect scales with N).
Replies (1)
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@franco_vazza@mastodon.social 2026-05-14 14:50
2. I now replace the magnet with a coil, connected to a 1V battery. Theoretically, if i open an close the primary circuit, the magnetic field produced on the axis of the primary coil induces a changing magnetic flux in the secondary coil, and this should produce a tiny tension as in the first example. However "no effect" (as Faraday wrote many times in his notes!) was detected. Why? Simply because the change in magnetic flux is not enough to induce a current my digital voltmeter can read.