Measuring current with ammeters


One of our member, Nasir, has thought of another tutorial series which is “Measuring Instruments for Electrical Engineers”.

In this series, he will focus on several instuments one by one and explain how it works and how to use it.

Pretty exciting isn’t it? Now check the 1st tutorial on ammeters

What is an Ammeter?

The first question that needs to be answered according to rules before formally telling about the various functions of the device is that what it is basically used for. So an ammeter is a current measuring device that is used for measuring the amount of current flowing through a circuit.

Since we all know that electric current is measured in Amperes, which is the unit of current, so an ammeter is named after it since it measures the amount of amperes in the circuit.

How does an ammeter measure current?

An ammeter works on the basic principle that when a current changes in a circuit, it produces a magnetic field. There are various types of ammeters and the interesting fact is that all of them are based on this very same principle. Some of the commonly used types of ammeters are:

  • Moving Coil Ammeters
  • Moving Magnet Ammeters
  • Electrodynamics Ammeters

Although the names are self-explanatory to quite an extent but a brief explanation about the working each of these commonly used ammeters is given below to help you guys understand them better.

Moving Coil Ammeters

A moving coil ammeter is more commonly also known as D’Arsonval galvanometer. It is known as moving coils because when the current passes through the coil of the ammeter the coil moves in the magnetic field produced by the passing current.

One important thing that should be noted about the moving coil ammeter is that the indicating needle of the ammeter at the displaying end moves in the opposite direction of the current due to the polar magnetic field present around the coil. We get the average value of the current through this thing. But since the average value of AC current is zero so this type of ammeter is not suitable for measuring AC currents but is instead used for measuring DC current values.

A moving coil ammeter is shown in the figure below:

Measuring Current with Ammeters 1

Moving Magnet Ammeters

A moving coil ammeter is very much similar to a moving magnet ammeter except for the fact that is evident through the name that the magnet moves in this case in place of the coil. In a moving magnet ammeter the coil is fixed and mounted on the case and the magnet is responsible for moving the indicating needle of the ammeter to display the value of current.

One advantage of this configuration over moving coil ammeters is that we can make the coils of thick wire to let pass more heavy amounts of current since the coil does not need to move so its thickness does not need to be limited.

A moving magnet ammeter is shown in the figure below:

Measuring Current with Ammeters 2

Electrodynamics Ammeters

This is also similar to the moving coil ammeter except for the fact that a permanent magnet is used in a moving coil ammeter whereas an electromagnet is used in place of a permanent magnet in this case.

This fact helps such that now we can measure the true RMS value of the current in place of the average value, so this ammeter can be used for measuring both AC and DC currents.

Connecting an Ammeter in the circuit

An ammeter is always connected in series in the circuit as shown below:

Measuring Current with Ammeters 3


The ammeter can be used to measure both the DC and AC current.

  • This comes in all sizes and can be used anywhere to measure the current like in electric heaters, cars, heavy and sensitive machinery, fridges etc.
  • They are also used in other electrical devices for measuring the range of current that enters them. Many companies manufacturing electrical devices extensively use ammeters to measure the current range and input output flow of current in their product.
  • Educational institutes also make use of ammeters in various laboratory experiments and to help students in the understanding of its functioning and working.
  • When buildings are being constructed and their electrical map is being implemented, ammeters are an essential component to check the input and output currents at various sites to assure safety and protection.

TOP 5 Best Sellers Ammeter on amazon

Bestseller No. 1
AstroAI Digital Multimeter with Ohm Volt Amp and Diode Voltage Tester Meter (Dual Fused for...
2,406 Reviews
AstroAI Digital Multimeter with Ohm Volt Amp and Diode Voltage Tester Meter (Dual Fused for...
  • ACCURATELY MEASURES: AC/DC Voltage, DC Current (Not AC Current), Resistance, Continuity, Diodes and more
  • TROUBLESHOOTS SAFELY: Automotive and household electrical problems safely and accurately; Overload protection on all ranges
  • EASE OF USE: Data hold and large digital display with backlit LCD for visibility in dimly light areas; Sampling speed: 2x per second
  • 1 Year Warranty. Built-in kickstand for hands-free use. Protective rubber corner guards for drop protection
  • NOTE: This meter can not test AC Current; Ensure your multimeter is set to the correct setting before testing
Sale 2019Bestseller No. 2
Etekcity Digital Multimeter, Amp Volt Ohm Voltage Tester Meter with Diode and Continuity Test, Dual...
2,205 Reviews
Etekcity Digital Multimeter, Amp Volt Ohm Voltage Tester Meter with Diode and Continuity Test, Dual...
  • Accurately measures: AC/DC voltage, only for DC current (not for AC current), resistance, diode, continuity, and more. Sampling speed: 3 times per second
  • Ease of use: data hold button holds a reading; large backlit LCD with large digits is easily visible in dimly lit areas. Built-in support stand allows for hand free use
  • Safety protection: overload protection on all ranges. Protective rubber sleeve around the Multimeter adds extra drop protection
  • 2-Year : 1-year buyer assurance (with a free option to extend it by 1 more year), and lifetime support from Edacity
  • Note: This Multimeter cannot be used to test AC current! Please make sure the rotary switch is located at the right range during use
Bestseller No. 3
Neoteck Auto Ranging Digital Multimeter AC/DC Voltage Current Ohm Capacitance Frequency Diode...
893 Reviews
Neoteck Auto Ranging Digital Multimeter AC/DC Voltage Current Ohm Capacitance Frequency Diode...
  • 【2000 Counts 8233D PRO Pocket Digital Multimeter】 2000μF Capacitance and 200KHz Frequency Measurement, Accurately Measures Current, Voltage, Resistance, and More, Maximum Reading over Time,...
  • 【Included 9 Volt Battery】The Compartment Lid at the Back is Secured by One Cross Head Screw, Not Difficult to Remove at All; Also, Included Pair Test leads and Pair Banana Plug to Alligator Clip...
  • 【CE Rated Digital Mulimeter with Over Load Protection】 Designed to Safely and Accurately Troubleshoot a Variety of Automotive and Household Electrical
  • 【Large Backlit LCD Display】 Auto Polarity Display, Easy to Read Large Backlit LCD Display, Back-light Makes a Real Difference in Low Light Areas
  • 【Nice Protective Orange Shell with Stand Built】 The Case with Our Multimeter is Some Kind of Non Slip, Slightly Soft Plastic that Will Help with Drop Protection, The Stand Places the Device at a...
Bestseller No. 4
INNOVA 3320 Auto-Ranging Digital Multimeter
2,797 Reviews
INNOVA 3320 Auto-Ranging Digital Multimeter
  • UL certified product designed to safely and accurately troubleshoot a variety of automotive and household electrical problems
  • Auto-ranging scales eliminate the need to dial in the correct range when making electronic measurements
  • Features large digital display and color coded LED's for battery quick check
  • Single-setting resistance function for AC and DC voltage
  • Protective rubber corner guards for drop protection
Sale 2019Bestseller No. 5
Klein Tools 69149 Electrical Test Kit
260 Reviews
Klein Tools 69149 Electrical Test Kit
  • The MM300 multimeter measures AC/DC voltage, DC current and resistance and has a safety rating of CAT III 600V, Class 2, Double insulation
  • The NCVT-1 has a bright green LED to indicate the tester is working; it changes to red and warning tones sound when voltage is detected
  • NCVT-1 has a digitally-controlled ON/OFF power button and auto power-off feature to conserve and extend battery life
  • Receptacle tester detects wiring configurations and indicates correct wiring, and identifies common wiring faults
  • Identifies open ground, open hot, open neutral, hot/ground reversed; it does not indicate quality of ground, multiple hot wires, or a combination of defects


In short it is one of the major devices which is extensively used in our everyday life without even the acknowledgement of a common man. Similarly there are other similar devices to measure the voltage, resistance, capacitance, inductance etc which are used along with ammeters to measure various parameters.

So in our next tutorials I am going to discuss each one of them one by one for better understanding and know-how of these measuring devices.


1 Comment

  • I have been trying to come up with a electrical problem I have and would like input from your bloggers.
    I have a customer with a barn style sliding glass door (floating door). I require a electrical connection to the glass panel. This poses a problem as a door loop is not suitable and there is no door jamb to install a contact. The voltage is 50 Volts AC and about 15watts. I have looked into a inductive power transfer unit but only can find DC units. I would have to run a inverter on both sides of the IPT. If anyone knows of a sliding track system that carries voltage or a IPT that would be more suitable I would appreciate the input. Thanks

Leave a Comment