Signedon faceplate: CENTRAL SCIENTIFIC CO. / LABORATORY SUPPLIES / APPARATUS CHEMICALS / CHICAGO, U. S. A.
Inscribedon one side of magnet: N
FunctionThis motor was meant to demonstrate a homopolar motor. A power source, connected via one of the binding posts (for instance, the black one), would pass an electric current to the hub of the copper disc. The rim of the disc would sit in the mercury-filled trough. Because mercury conducts current, the electricity would run from the hub to the rim to the mercury. The other contact to the power source (the red one) would sit in the mercury. With the circuit closed, and the current flowing, the surrounding U-shaped magnet and its resultant field cause the disc to rotate.
ProvenanceFrom Science Center Lecture Room, formerly from Allston Burr 11/10/79.