Measurement Tools

Ammeter, Definition, Types, Uses And Work

We express that what are the types of ammeter? with definition, its work and uses for students, teachers and engineers to completely understand the ammeter. Lets Read Physics…

What is an ammeter?types of ammeter

An ammeter is a measuring instrument used to measure the electrical current that passes through a circuit. These instruments are composed of a galvanometer and a series of resistors in parallel called shunts.

The galvanometer is also used to measure electrical current but in very small quantities

How does an ammeter work?

An ammeter is composed of a galvanometer which is built with an indicator needle, a spring, a coil and 2 permanent magnets and its operation is based on magnetism. The needle is attached by a spiral spring to the axis of a rectangular coil, which is suspended due to the magnetic field of the magnets.

Because the coil is controlled by the magnetic poles of the magnets, when a current passes over it, it generates its own magnetic field, which makes it rotate depending on the direction and strength of this electrical intensity.


An ammeter typically has several scales of measurement. This is where the series shunt resistors come into play as each represents a different scale. The resistors are placed in parallel to the coil so that most of the electrical current passes through them and only a small part through the coil, but that small part remains proportional to the total intensity.

Shunt resistance

How do I use an ammeter?

There are different types of ammeters but there are only 2 ways to measure current.

Hook ammeter types of ammeter

With this type of ammeter, making a current measurement is quite simple, since it is only necessary to put the cable to be measured inside the clamps and it will show you the current measured on its display.

Hook ammeter

Conventional ammeter

If you are a beginner with this instrument, making a measurement can be a bit more complicated, because it is necessary to open the electrical circuit and connect it so that the ammeter is in series with the circuit.

Conventional ammeter 

What types are there?

We can find a wide variety of ammeters, most of them are classified by their construction. Be it mechanical, thermal, digital, analog, etc.

Analog types of ammeter

This type was one of the first to be built, its operation is based on an indicator needle which stops at the number or fraction of the measured value.

Within this category we can find the terms and electromechanical types.

Thermal types of ammeter

Its operation is based on the expansion of a conductor, since the expansion is proportional to the heat and, according to the joule’s law, the heat is proportional to the square of the current, this instrument is capable of measuring alternating or direct current, since the heat is the same for one way or the other. The current passes through a resistor, which heats up as the current passes through a thermocouple which is connected to a galvanometer.

Thermal ammeter


Its operation is based on that of the coil with magnets, only there is a great variety of this kind.

  • Moving coil
  • Moving magnet
  • Ferromagnetic or moving iron
  • Electrodynamics

Digital types of ammeter

These instruments originated with the advancement of technology since they eliminate reading errors, because the measurements are displayed on a screen with numbers and all the moving parts were exchanged for electronic circuits.

Amperometric clamp

This is practically the most used in the industry since to make a measurement it is not necessary to open the circuit, it is enough to put the cable inside the clamps and it will indicate the measured value. Its operation is based on the magnetic field generated by the cables when a current passes over them.


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