What is a Galvanometer : Working, Construction & Its Applications

The Galvanometer development was done from the observation of a magnetic compass needle when it deflects close to an electrical wire. In 1820, a Danish physicist & chemist namely ‘Hans Christian Ørsted’ was discovered the first instrument to notice & calculate some amount of current to create magnetic fields. This was the primary connection established between electricity as well as magnetism. A French physicist & mathematician namely ‘André-Marie Ampère’ gave a mathematical expression for the discovery of Hans Christian & named the device after the researcher ‘Luigi Galvani. He discovered the frog galvanoscope principle in the year 1791 that is; electric current will make the dead frog legs jerk. In many fields, sensitive galvanometers are mandatory in the development of science & technology.

Table of Contents

  • What is Galvanometer?
  • Galvanometer Construction
  • Moving Coil
  • Suspension
  • Mirror
  • Torsion Head
  • Working Principle of Galvanometer
  • Working
  • Advantages and Disadvantages
  • Applications

What is a Galvanometer?

Definition: An electromechanical instrument that is used for noticing & signifying an electric current is known as galvanometer This works as an actuator by generating a rotational deflection in reply to the flow of current throughout a coil in a stable magnetic field.


The first galvanometer was not adjusted; however, after its developments were utilized like measuring instruments called as ammeters. These are mainly used to calculate the flow of current in an electric circuit.

These instruments are used like the visualizing part in different types of analog meters. The best examples of the analog meter are VU meter; light meter, etc. These meters are used to calculate & exhibit the o/p of other sensors. At present, the main type of galvanometer device used in different applications is the moving coil, D’Arsonval/Weston type.

Galvanometer Construction

The construction of the galvanometer is shown below. The main parts in this instrument mainly include the suspension, moving coil, & stable magnet.


  Moving Coil

This is the current-carrying element in the galvanometer. This coil is in a circular otherwise rectangular shape with the no. of twists of copper wire. This coil moves freely between the stable magnet poles. The iron core gives the low reluctance flux lane & therefore gives the tough magnetic field for the twist to move in.


The balancing of this coil can be done through a plane ribbon. This ribbon supplies the flow of current toward the coil. The other coil which carries the current is the lower suspension and the torque effect of this can be negligible.

The designing of the upper suspension coil can be done with a gold wire or copper wire in the ribbon form. However, the strength of this wire is not extremely tough so the galvanometer handles cautiously without any pulls.


The suspension in the galvanometer includes a little mirror that throws the ray of light, which is located on the scale where the deflection can be measured.

  Torsion Head

This is used to control the location of the coil as well as to adjust the setting of zero settings.

Working Principle of Galvanometer

The main function of the galvanometer is to decide the existence, direction, as well as electric current strength in a conductor. This works on the rule of converting energy from electrical to mechanical.

Once the current supplies in a magnetic field, a magnetic torque can be experienced. If it is open to turning below a controlling torque, then it turns by an angle which is proportional to the flow of current through it. This instrument is a kind of ammeter, used to detect and measure electric current.


Whenever a galvanometer is allied to a circuit, then the flow of current will be there in the coil. As the coil is delayed within a magnetic field, then a deflecting torque works upon it. Because of this torque, a coil in the galvanometer will start revolving from its place.

When the coil spins, the springs for controlling will be twisted & a stretchy restoring torque can be developed within them, after that it resists the revolving of the coil.

The coil’s rotation angle will be proportional to the torque. As the restoring torque turns into equivalent to the deflecting torque, then the coil relaxes in a stable position. A galvanometer is mainly used in various electrical circuits for detecting current as well as in experiments to decide the null point.

If a heavy current flows through the coil in the galvanometer, then the pointer in this may strike the stop pin because of very large deflection. So the coil in the galvanometer may blaze because of extreme heat which is generated.

So this can be protected from these possible harms by using a wide wire otherwise by connecting a copper strip in parallel with its coil which is known as a shunt. When compared to the coil’s resistance, its resistance is extremely small. Thus, most of the current flow supplies through the shunt & some amount of current supplied through the coil. Therefore, there is no chance of harm to the coil.

Advantages and Disadvantages

The advantages of the galvanometer include the following.

  • They will not affect by a strong magnetic field
  • Accurate & reliable
  • Scales of this is uniform

The disadvantages of the galvanometer include the following.

  • Overload can spoil any kind of galvanometer.
  • The temperature change will cause a change within restoring torque.
  • We cannot change the restoring torque easily.
  • These cannot be used for AC quantities measurement.


The applications of this include the following.

  • It is used to detect the flow of the current’s direction within the circuit & also determines the null point.
  • It is used to determining the current.
  • By using this we can determine the voltage between two points.
  • They are used in control systems, laser engraving, laser TVs, laser sintering, laser displays, etc.
  • They are used in the CD/DVD players & hard drives for controlling the position of head servos.
  • They are used in a film camera to get the readings of photoresistor in the metering mechanisms


1). What is the purpose of a galvanometer?

It is used to detect & measure electric current

2). What is the working principle of a galvanometer?

It works on the principle of conversion of energy from electrical to mechanical.

3). What is the main difference between ammeter & galvanometer?

The main function of the ammeter is, it shows both the magnitude & direction of the current.

4). What is the unit & resistance of the galvanometer?

The unit of this is microamps whereas the resistance is about 100 ohms

5). What is the SI unit of a galvanometer?

The SI unit is ampere per division.

Thus, this is all about the galvanometer and it’s working. This is one kind of instrument, used to measure & detect the flow of current within the current. These instruments are also used as the ammeters or analog measuring devices to calculate the direct flow of current in an electric circuit. Here is a question for you, what is the use of galvanometer?

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