Which device is used to measure voltage in an electrical circuit?

The device specifically designed to measure voltage in an electrical circuit is the voltmeter. Voltmeters operate by being connected across two points in the circuit where voltage needs to be measured. They provide a direct reading of the electrical potential difference, which is crucial for understanding how much voltage is present at various points in the circuit.

Amperemeters, on the other hand, are used to measure current, not voltage. Wattmeters are used for measuring electrical power, which involves both voltage and current but doesn't provide a direct voltage measurement. Ground testers are specialized devices for assessing the resistance of grounding systems, rather than measuring voltage directly. Therefore, the voltmeter is the appropriate choice for measuring voltage.