Which sensitive device measures current using the motor effect in its operation?

A galvanometer is a sensitive device designed to measure small currents with high accuracy by utilizing the motor effect. The motor effect refers to the principle that a current-carrying conductor placed in a magnetic field experiences a force. In a galvanometer, when an electric current flows through a coil of wire situated in a magnetic field, the coil experiences a torque due to the magnetic forces acting on it. This torque causes the coil to rotate, and the degree of rotation is proportional to the amount of current passing through the coil.

The reading on the galvanometer provides a direct indication of the current's magnitude. The sensitivity of the galvanometer is enhanced by the use of a spring mechanism that allows for precise measurements and returns the needle to its original position when the current is no longer present.

In contrast, a resistor does not measure current; rather, it restricts the flow of current in a circuit. An inductor stores energy in a magnetic field when current flows through it but does not measure the current itself. A capacitor stores energy in an electric field and is used to filter or smooth out signals, also without measuring current directly. Thus, the galvanometer's unique function of translating the physical movement of its needle into a measurement of current distinguishes it from the