What does a voltmeter measure in a circuit?

A voltmeter is specifically designed to measure the voltage across two points in an electrical circuit. This means it quantifies the electric potential difference, which indicates how much work is done when a charge moves between those two points. The measurement is usually expressed in volts (V).

The other options describe different electrical concepts. The flow of charge is measured in amperes by an ammeter, which tracks the current in the circuit. Resistance, which is measured in ohms, determines how much the circuit opposes the flow of electric current and is typically measured using an ohmmeter. Power, measured in watts, refers to the rate at which electrical energy is consumed or produced in a circuit and can be calculated using voltage and current values but is not directly measured by a voltmeter. Understanding these distinctions helps clarify the specific role of the voltmeter in an electrical system.