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What is an Ammeter? Definition and Function

Rashid Nuzha, Damien Howard
  • Author
    Rashid Nuzha

    Rashid holds a Postgraduate Diploma in Professional Studies in Education from The Open University-United Kingdom and a Bachelor of Science in Physics and Mathematics. He has 10+ years of experience from theory to practice in educational leadership and management.

  • Instructor
    Damien Howard

    Damien has a master's degree in physics and has taught physics lab to college students.

Learn about and explore the usage of the ammeter. Understand the ammeter and how it works. Discover what an ammeter does in a circuit and its various functions. Updated: 01/19/2022

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What is an Ammeter?

What is the ammeter definition and what is ammeter? Think of a device or instrument that can be used to measure either direct or alternating electric current in amperes that flow in an electric circuit. The ammeter explanation starts by looking at it as a tool. To understand what is the meaning of ammeter, remember that the electric current in a circuit is measured in amperes, so the device used to measure it is called an ampere meter or, in short (am-meter) ammeter. An ammeter must have a very low resistance once connected in series in the electric circuit so that the electric current can flow easily through it to be correctly measured.

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How Does an Ammeter Work?

To learn how does an ammeter work, recall that an ammeter measures the current in an electric circuit through a set of coils with very low resistance and inductive reactance. Once connected in series, the ammeter causes a very small drop in voltage due to its low resistance, allowing the electric current to pass through it and be measured. There are many ammeters to measure direct or alternating current, but all depend on the ammeter having very low internal resistance. Inside the ammeter, there is a shunt connected in parallel to a device called a galvanometer. The shunt is a resistance that allows the measured current to flow through the ammeter and delivers a full reading. The galvanometer is a sensitive current detector. Readings of electric currents in the ammeter are usually given in milliamperes in electric circuits that have batteries as a power source. In alternating current cases, such as at home, an ammeter will read larger values which will be in amperes.


Ammeter parts

Ammeter parts to help support the question how does an ammeter work


What Does an Ammeter Do in a Circuit?

To know what does an ammeter measure recall that the name is made of two parts: ampere and meter, so an ammeter measures amperes or, in other words, electric currents: direct or alternating. An ammeter only measures electric current. To measure an electric current is what is an ammeter used for once connected in series in an electric circuit. To learn what does an ammeter do in a circuit, think about how the electric current flows through the internal parts of the ammeter, causing its needle to deflect and showing the electric current strength in the targeted part of the electric circuit.


Ammeter

Ammeter function


Some ammeters are equipped with analog screens. In this case, instead of the needle, the screen shows in digits the electric current strength and the type of current. Therefore, knowing what is an ammeter in a circuit gives access to the electric current strength while never changing the potential difference in the circuit due to its low internal resistance. It is essential to remember that an ammeter must always be connected in series. The very small internal resistance of the ammeter can lead to a short circuit if the ammeter is set up in a parallel connection with the part of the circuit to measure the passing current. So ammeter function is a tool used to measure the current in a circuit while being connected in series with the circuit so that the measured current flows directly through the ammeter. It is important to set up an ammeter correctly - always in series - to measure the current passing through a resistor or any part of the circuit in an electric circuit.


Ammeter in a circuit

Ammeter in a circuit to support the ammeter explanation


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Frequently Asked Questions

What is an ammeter in a circuit?

An ammeter in a circuit gives access to the electric current strength while never changing the potential difference in the circuit due to its low internal resistance. It is very important to remember that an ammeter must be always connected in series.

What is the use of ammeter?

An ammeter is used to measure an electric current. An ammeter is a device or instrument that can measure either direct or alternating electric current in amperes that flow in an electric circuit.

How does an ammeter work?

Recall that an ammeter measures the current in an electric circuit through a set of coils with very low resistance and inductive reactance. Once connected in series, the ammeter causes a very low drop in voltage due to its low resistance, and that allows the electric current to pass through it and be measured.

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