A device that uses an electromagnet to measure electric current is called what?

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

Answer: (B)

Measuring current through magnetic deflection is the hallmark of a galvanometer. A galvanometer has a coil that carries the current and sits in a magnetic field; the interaction between the magnetic field and the current produces a torque that makes the coil—and the attached pointer—deflect. The amount of deflection is proportional to the current, giving a direct readout of how strong the current is.

An ammeter also measures current, but in practice it’s built around a galvanometer with a low-value shunt to handle larger currents without wasting voltage. A voltmeter, by contrast, targets voltage and uses a high-resistance path to limit current draw, while a multimeter can measure several quantities but isn’t defined by the electromagnet-based current sensing on its own.