A New Type of Photoelectric Effect in Cuprous Oxide in a Magnetic Field

Abstract

WHEN a plate immersed in liquid air and placed in a magnetic field parallel to its plane is illuminated by a beam of white light perpendicular to its plane, an electromotive force E is produced between A and B (Fig. 1). This electromotive force changes its sign when the magnetic field is reversed, its absolute value remaining unaltered. We investigated the dependence of E upon the intensity of the magnetic field H and found that up to fields of about 2,500 gauss, E is a linear function of H, the maximum electromotive force at this field strength reaching 2.7 volts. It may be noticed also that when the plate is illuminated from the opposite side, with the direction of the current in the electromagnet remaining unchanged, the electromotive force is reversed in sign. The existence of this electromotive force must evidently be looked upon as an indication of the fact that electric current is flowing perpendicularly to the plane of the plate. An examination of the sign of the electromotive force observed proves that the direction of the supposed flow of the negative electrons coincides with the direction of the light beam, assuming that under the influence of the magnetic field the electronic current is deflected in the normal way.