When measuring voltage in a circuit, a voltmeter should be connected in which configuration?

When measuring voltage in a circuit, a voltmeter should be connected in which configuration?

• A. Series
• B. Parallel
• C. Across the Source Only
• D. Across the Load Only

Answer: (B)

Voltage is the potential difference between two points, so you measure it by placing the meter across those two points. That means connecting the voltmeter in parallel with the component or across the source. The voltmeter’s very high input resistance lets it draw almost no current, so it doesn’t disturb the circuit while it reads the exact voltage difference between the two points. If you wired it in series, it would become part of the current path and its own resistance would alter the circuit and give an inaccurate reading. In practice, you place the probes on the two terminals you want to measure—such as across a transformer or across the load—to see the voltage the element actually experiences.

Voltage is the potential difference between two points, so you measure it by placing the meter across those two points. That means connecting the voltmeter in parallel with the component or across the source. The voltmeter’s very high input resistance lets it draw almost no current, so it doesn’t disturb the circuit while it reads the exact voltage difference between the two points. If you wired it in series, it would become part of the current path and its own resistance would alter the circuit and give an inaccurate reading. In practice, you place the probes on the two terminals you want to measure—such as across a transformer or across the load—to see the voltage the element actually experiences.