Which of the following best describes how a voltmeter works?

A voltmeter is a specific instrument designed to measure the potential difference, commonly referred to as voltage, between two points in an electrical circuit. Voltage can be thought of as the electrical pressure that drives the flow of current through a circuit.

When you connect a voltmeter across two points, it measures the difference in electric potential energy per unit charge between those points. This is crucial for understanding how much energy is available to push charges through the circuit, thus helping to analyze circuit performance, design, and troubleshooting.

The design of a voltmeter is such that it has a very high internal resistance to ensure it does not draw significant current from the circuit, allowing for an accurate measurement of voltage without affecting the operation of the circuit itself.

In summary, option B accurately encapsulates the functionality of a voltmeter by stating that it measures the potential difference between two points in a circuit. This fundamental understanding is essential for anyone studying electricity and electronics, especially in practical applications.