Which instrument is used to measure electric potential or electromotive force?

The correct answer is a voltmeter because it is specifically designed to measure electric potential difference, also known as voltage, across two points in an electrical circuit. Voltage is a critical parameter in electronics that indicates how much electric potential energy exists to move electrons through a conductor.

A voltmeter is typically connected in parallel with the component across which the voltage is being measured, and it provides readings in volts (V). This instrument is essential for diagnosing circuit conditions, ensuring components receive the appropriate voltage, and determining if circuits are functioning as intended.

Other instruments mentioned serve different purposes. An ammeter measures current, which is the flow of electric charge, while an ohmmeter measures resistance within a circuit. A wavemeter, on the other hand, is used in radio and communication applications to measure the frequency of radio waves rather than electrical potential. Understanding these distinctions is important for effective use of measurement tools in ham radio and other electrical applications.