A galvanometer is an instrument used to detect and measure small electric currents. It operates on the principle that a magnetic field interacts with a current-carrying coil, causing it to move. This movement is typically indicated by a needle on a dial, allowing users to read the current's strength. Galvanometers are essential in various applications, including laboratory experiments and electrical engineering. They can be found in devices like ammeters and voltmeters, which measure current and voltage, respectively. Additionally, they are used in oscilloscopes to visualize electrical signals over time.