ROTATION INDUCED ELECTROMOTIVE-FORCES IN NORMAL AND SUPERCONDUCTING METALS

The theory of rotation induced emfs in normal and superconducting metals is discussed and the results of an experiment designed to measure such emf's are described. It is shown that for a normal rotor connected via superconducting sliding contacts to a stationary external circuit the expected emf is mv**2/e, twice what one might expect on the basis of simple calculations, whereas for superconducting rotors the expected emf is zero. An attempt was made to detect the predicted rotation induced emf due to a normal rotor and to put an upper limit on the emf generated by a superconducting rotor. In both cases, superconducting sliding contacts were used to connect the center to the rim of the rotating cylinder with a Clarke SLUG, used as a galvanometer. The observed emf's, although extremely small by ordinary standards, were several orders of magnitude larger than predicted and appeared to be an artifact generated by the sliding contacts.