What does ammeter mean?
An ammeter is a measuring instrument used to determine the magnitude of an electric current flowing through a circuit, expressed in amperes. The name combines 'ampere,' the unit of current named after the French physicist André-Marie Ampère, with 'meter,' the general term for a measuring device. Because current measurement requires the charge to pass through the instrument, an ammeter must be connected in series within the circuit, and it is designed to have very low internal resistance so that its presence does not significantly alter the current being measured. Ammeters range from traditional moving-coil pointer devices to modern digital displays and clamp-on meters that measure current without breaking the circuit. The word belongs primarily to the vocabulary of electrical engineering, physics teaching, and skilled trades, though it appears in any context where circuits are built, tested, or repaired. It is closely related to other '-meter' instruments such as the voltmeter and ohmmeter, and in practice all three functions are often combined in a single multimeter.
nounAn instrument for measuring the strength of an electric current in amperes.
- An instrument that measures electric current in amperes.
"The technician connected the ammeter in series with the circuit to check how much current the motor was drawing."
"Before replacing the fuse, she used an ammeter to confirm that the circuit was drawing far more current than it should."
"In the physics lab, students wired an ammeter in series with a resistor to verify Ohm's law."
Standard regular plural; used when referring to multiple instruments, e.g. in a laboratory inventory.
"The workshop stocked several digital ammers—rather, ammeters—for bench testing."
Every ammeter must be wired into a circuit in series — meaning the entire current you're measuring has to flow straight through the instrument itself.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of ammeter
The word ammeter derives from the combination of 'ampere,' the SI unit of electric current named for the early nineteenth-century French physicist André-Marie Ampère, and 'meter,' from the Greek 'metron' (measure). It was formed in the nineteenth century as electrical science industrialized and standardized instruments were needed to quantify current. It belongs to the same family of instrument names ending in '-meter' — such as voltmeter, ohmmeter, and galvanometer — all of which trace their measuring suffix back to Greek roots.
How ammeter is actually used
Ammeter is a technical term used mainly in electrical engineering, physics education, and trade contexts; it is neutral in tone and essentially universal across English-speaking regions. In everyday speech, people more often say 'multimeter' since most modern instruments combine ammeter, voltmeter, and ohmmeter functions.
Easily confused with ammeter
A voltmeter measures electrical potential difference (voltage) in volts and is connected in parallel, whereas an ammeter measures current in amperes and is connected in series.
A galvanometer detects and indicates small electric currents, often as a sensitive pointer instrument, while an ammeter is calibrated to read current directly in amperes.