A tangent galvanometer is a scientific instrument used to measure small electric currents. It consists of a circular coil of wire, usually mounted vertically, with a magnetic needle at its center. When current flows through the coil, it generates a magnetic field that interacts with Earth’s magnetic field, causing the needle to deflect. The angle of deflection is related to the current via the tangent law, hence the name. By measuring this angle, the current can be calculated. The device is most accurate when the coil is aligned with the magnetic meridian, and it's primarily used in educational demonstrations and experiments.