In an electric circuit, even if the switch or loop is closed, it is difficult to know whether the current is flowing, hence for this purpose galvanometer was introduced in the circuit.
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Galvanometers are electro-mechanical instruments that are used not only for detecting the passage of current flow but also to measure the current in a circuit or conductor
A galvanometer also performs the functions of an ammeter, therefore by a slight modification, galvanometers can be made into ammeter.
Principle of Galvanometer
The principle by which galvanometer work is that they convert electrical energy into mechanical energy,that is the current flowing in the magnetic field gets converted into magnetic torque.
The galvanometer acts as an actuator since it produces a rotary torque that deflects in the opposite direction.
Construction of Galvanometer
The basic construction of a galvanometer consists of a soft iron cylinder surrounded by a frame where a coil or wire is wound over the frame,a cylinder head magnet or permanent magnet is placed around the frame and a axial rod and pivot is placed in the form of spindle.An indicator or magnetic needle is used to indicate the readings on a scale.The readings on the scale is in ampere(A).
The working of a galvanometer is that in a current carrying coil, the current flowing is in a constant magnetic field and hence the magnetic needle or indicator gets deflected and measurement is noted.
Types of Galvanometer
There are many types of galvanometers used in the industry. Some common examples are :
Moving coil, tangent, ballistic, vibration, D’Arsonval, reflecting and mirror galvanometers, out of which D’Arsonval/Weston galvanometer is widely used in the modern generation.
Uses of Galvanometer
Earlier galvanometers were used to check if there is any fault in telecommunication cables,but now it used in positioning and control engineering,because of it’s high precision and accuracy.Galvanometers are used in ADC’s and by using it voltage can also be measured.