Which instrument is used to measure potential differences?

A multimeter is a versatile instrument commonly used for measuring various electrical characteristics, including potential differences, also known as voltage. It can measure direct current (DC) and alternating current (AC) voltages, which is essential in many troubleshooting scenarios. When set to the appropriate voltage setting, a multimeter provides a direct reading of the voltage present between two points in an electrical circuit.

The other instruments listed have specific purposes that do not include measuring potential differences effectively. An oscilloscope is primarily used for visualizing waveforms and analyzing how voltage changes over time, rather than providing a simple numerical reading of voltage. An ammeter is designed solely to measure current, not voltage, making it unsuitable for this purpose. A thermometer measures temperature and is unrelated to electrical measurements. Hence, the multimeter is the correct instrument for measuring potential differences.