What instrument is used to measure voltage?

The voltmeter is specifically designed to measure the electrical potential difference, or voltage, between two points in an electrical circuit. It is usually connected in parallel with the circuit component whose voltage is being measured. This parallel connection allows it to accurately read the voltage without significantly altering the circuit's operation.

While a multimeter can also measure voltage (among other parameters like current and resistance), its functionality encompasses a broader range of measurements, which is why it is versatile. However, when the question focuses solely on the instrument specifically designed for voltage measurement, the voltmeter stands out as the correct choice.

In contrast, an ohmmeter measures resistance, which is a different electrical property, while an ammeter is used to measure current flowing through a circuit. Thus, these instruments serve distinct purposes, and the voltmeter is the one explicitly meant for measuring voltage.