An instrument used to measure voltage in an electrical circuit is called a:

The instrument designed specifically for measuring voltage in an electrical circuit is known as a voltmeter. This device is essential in determining the potential difference between two points in a circuit, which is crucial for diagnosing electrical problems, troubleshooting circuits, and ensuring they operate within safe voltage levels.

Voltmeters are typically connected in parallel with the circuit component being measured, allowing them to measure the voltage drop across that component accurately. This function is pivotal in both practical and educational applications in the field of electronics and small engines, as understanding voltage levels can help ensure the proper operation of electrical systems.

In contrast, while an ammeter measures the current flowing through a circuit and an ohmmeter assesses the resistance of a component, a multimeter can measure multiple electrical properties such as voltage, current, and resistance, it is the specific function of measuring voltage that defines the voltmeter. Thus, the correct identification of a voltmeter as the tool for voltage measurement underscores its focused role within electrical measurement instruments.