Construction of Tangent Galvanometer

Construction of Tangent Galvanometer Points : Construction of Tangent Galvanometer Tangent Galvanometer is an absolute instrument used for calibration of secondary instruments. It is also called moving magnet galvanometer. Construction A simple and single coiled tangent galvanometer. It consists of a circular coil “C” of many turns of insulated copper wire would in a groove on a circular wooden frame. The frame is fixed vertically on a base provided with levelling screws. The two ends of the wire of the coil are connected to the two binding screws at the base of the frame. The frame is so arranged that the coil as a whole may be rotated about a vertical axis passing through the centre of the coil and coinciding with plane of the coil.

The position of the frame with the coil while rotated about the vertical axis i.e. the amount by which the coil is rotated can be ascertained by means a horizontal circular scale “S1” provided at the base of the instrument. A horizontal scale graduated in degrees is fixed at the centre of the coil. At the exact centre of the coil a small magnetic needle N—S with a long light aluminium pointer “P” fixed at its centre and perpendicular to itself is suitably pivoted.