What instrument is used to measure current?

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

Answer: (B)

Measuring current requires a device placed in the path of the circuit so it can carry the same current as the circuit. An ammeter is designed for this purpose and has very low resistance, so it doesn’t significantly affect the current it’s trying to measure. It reads in amperes, the unit of current, and is connected in series with the load to capture the actual flow of charge through the circuit.

Voltmeter, on the other hand, measures voltage and is connected in parallel to a component to determine the potential difference across it. Ohmmeter measures resistance and is typically used when the circuit is de-energized, applying a small test current and reading the resulting voltage to compute resistance. Wattmeter measures power, often using both voltage and current to determine electrical power consumption.