Which device utilizes an electromagnet to gauge electric current?

The correct answer is the galvanometer, which is specifically designed to detect and measure small electrical currents using an electromagnet. When an electric current passes through a coil of wire within the galvanometer, it creates a magnetic field that interacts with the magnetic field of a permanent magnet. This interaction causes the coil to move, and the degree of movement is proportional to the magnitude of the current. The movement of the coil is typically indicated by a needle on a calibrated scale, allowing for the precise measurement of the current flowing through the device.

In contrast, other devices mentioned do not specifically gauge electric current in the same manner. A voltmeter measures voltage, which is the electrical potential difference between two points but does not directly measure current. A multimeter can measure voltage, current, and resistance, but it operates on different principles and often includes a galvanometer as part of its functionality for current measurement. An oscilloscope visualizes electrical signals in the form of waveforms over time, allowing for detailed analysis of voltage changes but does not directly measure current itself.