Tangent galvanometer: Compass needle pivots in a coil.

Tangent galvanometer: Compass needle pivots in a coil. This is a simple galvanometer. A compass needle is placed inside a 25 cm. diameter coil of wire. When a key switch is pressed, current flows through the coil, producing a magnetic field. The compass will swing to a new position, depending on the coil current. The current in the coil is adjusted using the rheostat.