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What is a galvanometer?

A galvanometer is one of the instruments for measuring electrical current par excellence. This device is used on electrical circuits to know and measure the intensity and direction of electrical current. 

Any device can suffer irreparable damage if it experiences an electrical overload. A galvanometer can be used to prevent this from happening; they are made to measure the intensity of an electrical current and therefore be able to monitor it. 

It can be used in both domestic and industrial environments. There are simple galvanometers and those with a larger measurement scale, as well as more complexity, which enable measurement in industrial atmospheres.

How was the galvanometer invented?

In 1820, the German physicist Hans Oersted described how the needles of a magnetic compass could be deflected in the presence of an electrical current generated in a wire. That same year, German chemist Johann Schweigger described the possibility of using an instrument capable of measuring such a phenomenon. 

However, it was not until 1836 that the galvanometer was formally invented by Italian scientist Luigi Galvani. The researcher found that applying an electrical current to the spinal cord of a dead frog could generate muscle contractions in its limbs, achieving a movement similar to that made by the animal in life. 

What are the parts of a galvanometer?

While there are several types of galvanometers, they all have the same parts that make it possible to measure the flow of an electrical current with precision:

  1. Coil: the part of the galvanometer through which the electric current to be measured travels.
  2. Spring: the joint between the coil and the needle that gives the measurement. 
  3. Needle: the part that indicates the value of the measured electric current.
  4. Permanent magnet: responsible for producing the magnetic field that generates the coil’s movement, depending on the current.
  5. Scale: where the current’s magnitude and intensity are shown.

How does a galvanometer work?

A galvanometer works based on the magnetic force that causes a needle to turn; its movement is directly proportional to the intensity of the electric current in the circuit; that is, depending on whether the magnetic force is greater or less, it will make the measuring instrument’s needle turn more or less. 

The galvanometer has a permanent magnet that exposes the coil to its magnetic field. When electricity travels inside the coil, the needle inside it begins to turn with greater or lesser intensity, depending on the current circulating inside it. The coil’s rotation then causes the spring, which is connected to it, to move, as well. 

A galvanometer’s scale is graded into marks of the final value of the measurement, which corresponds to the intensity of the electrical current and is indicated by the instrument’s needle. 

What types of galvanometers are there?

Galvanometers can be divided into two types:

  1. Moving coil galvanometers: the most common type. In this type of instrument, the needle is connected to a coil by means of a spring, and a fixed magnet generates the magnetic field that makes the coil move. As the electrical current travels, it moves the needle proportionally to the current’s strength. 
  2. Moving magnet galvanometers: in this type, the moving part is the magnet, not the coil. When the electrical current travels through the latter, a magnetic force is generated that makes the magnet move. As a result, the needle is linked to the magnet, which also moves depending on the intensity of the electrical current. 

There are also portable galvanometers which can also be moving frame or moving magnet, depending on their design.

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