On the Existence of Time Lags in the Faraday Effect

Abstract

The nature of the initial or surge currents, and of the oscillatory currents, found in a magneto-optic apparatus similar to that used by F. Allison, has been investigated. Assuming the existence of a time lag in the Faraday effect, the nature of minima which could be produced by these currents is examined. The possible minima are found to be extremely broad, a matter of several meters rather than a few centimeters, and have such a small intensity change for a unit movement of the trolley as to be incapable of detection. Large and easily visible minima characteristic of the organic liquids used have been observed, whose explanation is found in terms of Verdet constant and a change in magnitude of current as a result of trolley movement. The effect of concentration on the appearance of minima arising from a Faraday effect is found not to agree with the experimental results of Allison. No sharp minima were found either with visual or photoelectric observation, and the conclusion is reached that the cause of the results of Allison is not a time lag in the Faraday effect, but is some as yet unknown cause, possibly a peculiar sort of Kerr phenomenon.