Which instrument is used to measure current in a circuit?

Which instrument is used to measure current in a circuit?

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

Answer: (B)

Current is measured by inserting a device in series with the circuit so the same current flows through it. The ammeter is built for this purpose and has very low internal resistance, so it minimizes any drop or disturbance to the circuit while accurately reading the current. In contrast, a voltmeter is placed in parallel across a component to measure voltage (it has high resistance to avoid drawing current), an ohmmeter measures resistance (usually on a de-energized circuit), and a wattmeter measures power by combining voltage and current. So the tool used to measure current directly is the ammeter.

Current is measured by inserting a device in series with the circuit so the same current flows through it. The ammeter is built for this purpose and has very low internal resistance, so it minimizes any drop or disturbance to the circuit while accurately reading the current. In contrast, a voltmeter is placed in parallel across a component to measure voltage (it has high resistance to avoid drawing current), an ohmmeter measures resistance (usually on a de-energized circuit), and a wattmeter measures power by combining voltage and current. So the tool used to measure current directly is the ammeter.