A galvanometer is best described as which of the following?

• A. Voltmeter for large voltages
• B. Ohmmeter for resistance
• C. Wattmeter for power measurement
• D. Ammeter for small currents

Answer: (D)

A galvanometer detects current by turning a small electric current into a measurable needle deflection. It uses a coil in a magnetic field, and the magnetic torque causes the needle to move; the amount of deflection is proportional to the current passing through the coil. Because it is highly sensitive, it responds to very small currents with noticeable movement, making it a current-sensing instrument for small currents. In practice, you can add a low-resistance shunt to extend its range and effectively turn it into an ammeter for larger currents, but the basic function remains measuring current. It isn’t used to directly measure voltage, resistance, or power, which would require a voltmeter, ohmmeter, or wattmeter. So the galvanometer is best described as an ammeter for small currents.