What measuring device uses a galvanometer to measure resistance?

The device that uses a galvanometer to measure resistance is a Wheatstone bridge. The Wheatstone bridge is a circuit arrangement that compares an unknown resistance with known resistances to determine its value. It operates based on the principle of balancing two legs of a bridge circuit, where one leg contains the unknown resistor. When the resistance in the unknown leg is adjusted, a galvanometer is used to detect the null point at which no current flows through it, indicating that the resistances are balanced.

While an ohmmeter also measures resistance and utilizes a galvanometer, it does so in a different manner where a current is passed through the resistor being measured and the galvanometer indicates the amount of current, which is then converted into a resistance value. However, the specific relationship to resistance measurement via circuit balance is a hallmark of the Wheatstone bridge.

Other devices mentioned serve different functions: a voltmeter measures voltage across two points in a circuit, and an ammeter measures current flow through a circuit. Therefore, the Wheatstone bridge stands out as the measuring device that directly employs a galvanometer for resistance measurements in its operation.