Which instrument measures the potential difference across components?

Which instrument measures the potential difference across components?

• A. Ammeter
• B. Ohmmeter
• C. Voltmeter
• D. Multimeter

Answer: (C)

Measuring potential difference, or voltage, is what a voltmeter is designed to do. The voltmeter is connected across the two points of the component, in parallel, so it reads the same voltage drop that exists across that component. Its very high input resistance means it draws almost no current, so it doesn’t disturb the circuit’s operation. In contrast, an ammeter measures current and must be placed in series, since current is the same through components along a path. An ohmmeter measures resistance by applying a small current and is used with the circuit powered down. A multimeter can measure voltage, current, or resistance depending on the setting, but when you want the specific measurement of potential difference across a component, the dedicated instrument is the voltmeter.

Measuring potential difference, or voltage, is what a voltmeter is designed to do. The voltmeter is connected across the two points of the component, in parallel, so it reads the same voltage drop that exists across that component. Its very high input resistance means it draws almost no current, so it doesn’t disturb the circuit’s operation.

In contrast, an ammeter measures current and must be placed in series, since current is the same through components along a path. An ohmmeter measures resistance by applying a small current and is used with the circuit powered down. A multimeter can measure voltage, current, or resistance depending on the setting, but when you want the specific measurement of potential difference across a component, the dedicated instrument is the voltmeter.