In this topic, you study the types of galvanometers.
Galvanometers are of many types including moving iron and moving coil types. Important classes of galvanometers are mentioned below :
(l) D’Arsonval galvanometer
(2) Ballastic galvanometer
(3) Vibration galvanometer
(4) Duddels oscillograph
(a) The D’Arsonval is the simple and most widely used galvanometer.
(b) The Ballastic galvanometer is used to measure the quantity of charge passed through it. Basically. it is employed to measure small changes such as obtained in magnetic flux measurements. The “Flux meter” is a special type of Ballistic galvanometer.
(c) The vibration galvanometers are the most widely used tuned detectors particularly as null point detectors in ac bridges. They are manufactured for a frequency range of the 5 Hz to I KHz. Where alternating currents are passed through the coil, it vibrates with the frequency of the currents. If natural frequency of the moving system is made equal to the frequency of applied current, mechanical resonance occurs and the moving system vibrates with high amplitude.
(d) The Duddels oscillograph is basically a vibration galvanometer having a low period of vibrations. The natural frequency is about 12 kHz.
