INTERACTIVE EXPERIMENTS AND EXHIBITS
AND IF THERE’S NO VARIATION IN FLOW?
Peter Barlow (1776-1862), English mathematician
La Ruota di Barlow (1822)
STRANGE GENERATORS AND STRANGE MOTORS WITH NO VARIATION IN FLOW
In this apparatus there is evidently no variation in flow linked to the conductor and thus Faraday’s Law would appear not to be applicable. What’s the explanation of what we have seen? (We suggest interpreting the facts by having recourse to Lorentz's Force).
The apparatus below has exactly the same structure as the generator we saw above. The conductor disk and the ring magnet are integral with each other. The contact on the periphery draws from a drop of mercury in the groove on the periphery of the disk through the large curved conductor.
And now the complement of the motor seen above.
The machines just seen belong to the category of so-called unipolar machines. An extreme case is that of a cylindrical magnet conductor polarized axially with a contact on the axis and another on the surface. When current is applied it begins to rotate. The oddity of such devices and the different interpretation of their behaviour, depending on whether the system of reference of the rotating part or the laboratory is used, suggested to Albert Einstein his first reflections on relativity, contained in the first paragraph of his work entitled "On the Electrodynamics of Moving Bodies" (1905), the founding act of restricted relativity.
And finally, of strange motors, here is the strangest of all!