In a D’Arsonval galvanometer, a disk wound with many turns of fine wire can rotate in the field of a permanent magnet, its deflection proportional to the current through the wire. A coil spring (not shown) provides a restoring torque to the disk. As part of an appropriate circuit, the galvanometer can function as a DC multimeter, measuring the voltage, current, or resistance of a connected circuit element, shown as a black rectangle. Depending on the mode selected—voltmeter, ammeter, or ohmmeter—the branch of the circuit shown in red is operative.