What does a voltmeter specifically measure?

A voltmeter is specifically designed to measure voltage, which is the electrical potential difference between two points in a circuit. This potential difference is what drives electric current to flow, making the measurement of voltage crucial in understanding how much energy is supplied or consumed in an electrical system.

Voltage, expressed in volts, indicates how much energy per unit charge is available to move charges through the circuit. By connecting a voltmeter across two points in a circuit, it can accurately indicate the voltage present between those points, allowing for the assessment of circuit performance and troubleshooting.

While the other options such as current, resistance, and power are important electrical quantities, they are measured using different instruments. For instance, current is measured with an ammeter, resistance with an ohmmeter, and power can be calculated using voltage and current but is not directly measured by a voltmeter. Understanding the role of a voltmeter enhances a student's ability to analyze and work with electrical systems effectively.