What is a voltmeter?

• A. A device for converting chemical energy to electrical energy
• B. An instrument designed to measure a difference in electrical potential in volts
• C. A device to measure frequency
• D. A device to store charge

Answer: (B)

A voltmeter is an instrument that measures electric potential difference, the voltage, between two points in a circuit and expresses it in volts. To do this without disturbing the circuit, it is designed with very high input impedance, so it draws almost no current. You place it in parallel with the component or portion of the circuit you want to know the voltage across, rather than in series.

This is different from other tools: a device that converts chemical energy to electrical energy is a power source like a battery, not a measurement tool. A device that measures frequency is a frequency meter, not a voltmeter. A device that stores charge is a capacitor, not a voltmeter.