Cathodic Protection Tester Practice Exam

What are typical uses for a voltmeter?

1. Measuring resistance

2. Measuring current flow

3. Measuring voltage drop across shunts

4. Measuring temperature

The correct answer is: Measuring voltage drop across shunts

A voltmeter is specifically designed to measure the electrical potential difference, or voltage, between two points in a circuit. One of its key applications is to measure the voltage drop across components such as shunts, which are often used to reduce the amount of current flowing through a circuit while allowing a smaller measurable current to flow. By measuring the voltage drop across the shunt, it's possible to infer the current flowing through the circuit using Ohm's Law, making this application vital in various testing and diagnostic procedures, especially in cathodic protection systems. In contrast, while a voltmeter also interacts with electrical circuits, it does not typically measure resistance, current flow directly, or temperature. Measuring resistance requires an ohmmeter, measuring current flow requires an ammeter, and measuring temperature involves thermometers or thermocouples. Each of these instruments operates under different principles suited to their specific measurement tasks, distinguishing them from the voltmeter's primary function.