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Abstract

A new microwave technique has been developed for the experimental study of small amplitude surface waves on an electrically conducting fluid. The fluid forms one of the walls of a resonating, microwave cavity. Surface waves with amplitudes as small as 10⁻³ cm. can be measured by observing the resulting change in the resonant frequency of the cavity. This technique has been successfully used to measure the viscous and magnetic damping coefficient of a small amplitude, standing, surface wave in liquid mercury. The magnetic damping, coefficient (for a vertical, magnetic field) was found to be in good agreement with a calculation that was made, for low magnetic Reynolds numbers. When the viscous damping coefficient was compared with the standard theory, which allows horizontal motion of the. surface, a disagreement of up to a factor of four was found. It, however, showed excellent agreement with a modified theory which assumes that there, is no horizontal motion of the surface.