What is Galvanometer?
A '''galvanometer''' is a type of [[ammeter]]. It is an instrument for detecting and measuring [[electric current]]. It is named after [[Luigi Galvani]]. It is an analog electromechanical transducer that produces a rotary deflection, through a limited arc, in response to [[electric current]] flowing through its coil. The term has been expanded to include uses of the same mechanism in recording, positioning, and [[servomechanism]] equipment. == Operation == The most familiar use is as an analog measuring instrument, often called a [[Meter (electronics)|meter]]. It is used to measure the direct current (flow of electric charge) through an electric circuit. The D'Arsonval/Weston form used today is constructed with a small pivoting coil of wire in the field of a permanent [[magnet]]. The coil is attached to a thin pointer that traverses a calibrated scale. A tiny [[torsion]] [[Spring (device)|spring]] pulls the coil and pointer to the zero position. When a [[direct current]] (DC) flows through the coil, the coil generates a magnetic field. This field acts against the permanent magnet. The coil twists, pushing against the spring, and moves the pointer. The hand points at a scale indicating the electric current. Careful design of the pole pieces ensures that the magnetic field is uniform, so that the angle of the pointer is proportional to the current. A useful meter generally contains provision for damping the mechanical [[resonance]] of the moving coil and pointer, so that the pointer settles quickly to its position without oscillation. == Tangent galvanometer == [[File:Western Union standard galvanometer.jpg|thumb|150px|right|Tangent galvanometer made by J.H.Bunnell Co. around 1890.]] A tangent galvanometer is an early measuring instrument used for the [[measurement]] of electric current. It works by using a compass needle to compare a magnetic field generated by the unknown current to the magnetic field of the Earth. It gets its name from its operating principle, the tangent law of [[magnetism]], which states