The galvanometer is an indicating instrument. This instrument mainly detects the presence of any small electric signal in a circuit. Although this instrument can measure currents and voltages. But we normally use this instrument to detect the presence of currents and voltages. Usually we avoid it for measuring purposes because its insufficient accuracy.
Types of Galvanometers
There are several types of the instrument. For examples, moving coil type and moving magnet type are two very popular form. The permanent Magnet Moving Coil (PMMC) type is most popular. We also refer it as D’Arsonval Galvanometer. It is a DC instrument. Also, there are many other types of galvanometers. Among which, the Ballistic galvanometer measures quantity of electricity. Another type is vibration galvanometer. Again we can categories vibration type as moving magnet type and moving coil type. Although we more generally use moving coil type. This is because, stray magnetic field can seriously affect the performance of moving magnet type.
Application of Galvanometer
We generally use this instrument in bridge circuits and potentiometers. It helps to identity the exact balance condition of Wheatstone bridges and other types of bridge circuits. In potentiometer galvanometer does the same job.
Properties of an Ideal Galvanometer
- No external magnetic field or electric field can seriously affect the performance of the instrument. So, the instrument should have proper magnetic screening mainly when it is a moving magnet type instrument.
- Since, we generally use this instrument as the null director, it must have a stable zero.
- Fast reading is another criteria of a good galvanometer. So, it must have short periodic time.
- To get quick detection of electrical signal, the instrument must not have unnecessary oscillations of the pointer. Therefore it must have a critical damping.
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