THE MEASUREMENT OF THE FARADAY-EFFECT IN ALTERNATING MAGNETIC-FIELDS - A NEW AND SIMPLE METHOD

A method of measuring the peak value of the Faraday rotation induced by a sinusoidal magnetic field is described. No rotating part is needed. The method is general and may, in theory, be used at any frequency. An accuracy better than 1% is reached, for rotation between 0.2 degrees and 60 degrees , at frequencies below about 20 kHz. The device has been tested with a water Faraday rotator for two field amplitudes and at three frequencies. This device may also be of interest in building sinusoidal magnetic field sensors or in studying the variation of the Faraday effect with modulation frequency.