 Wire carrying current to be measured
Spring providing restoring force An ammeter is a measuring instrument used to measure the flow of electric current in a circuit. Electric currents are measured in amperes, hence the name. The word "ammeter" is commonly misspelled or mispronounced as "ampmeter" by some. Diagram showing the basic internal workings of a coil galvanometer. ...
Captain Nemo and Professor Aronnax contemplating measuring instruments in Twenty Thousand Leagues Under the Sea In physics and engineering, measurement is the activity of comparing physical quantities of real-world objects and events. ...
Electric current is the flow of electric charge. ...
An electrical network or electrical circuit is an interconnection of analog electrical elements such as resistors, inductors, capacitors, diodes, switches and transistors. ...
The ampere (symbol: A) is the SI base unit of electric current. ...
The earliest design is the D'Arsonval galvanometer or moving coil ammeter. It uses magnetic deflection, where current passing through a coil causes the coil to move in a magnetic field. The voltage drop across the coil is kept to a minimum to minimize resistance in any circuit into which the meter is inserted. It has been suggested that Tangent galvanometer be merged into this article or section. ...
In physics, magnetism is one of the phenomena by which materials exert an attractive or repulsive force on other materials. ...
Current (I) flowing through a wire produces a magnetic field (B) around the wire. ...
International danger high voltage symbol. ...
Moving iron ammeters use a piece or pieces of iron which move when acted upon by the electromagnetic force of a fixed coil of (usually heavy gauge) wire. This type of meter responds to both direct and alternating currents (as opposed to the moving coil ammeter, which works on direct current only). General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ...
Wire gauge is a measurement of how large a wire is, either in diameter or cross-sectional area. ...
Direct current (DC or continuous current) is the continuous flow of electricity through a conductor such as a wire from high to low potential. ...
City lights viewed in a motion blurred exposure. ...
Direct current (DC or continuous current) is the continuous flow of electricity through a conductor such as a wire from high to low potential. ...
To measure larger currents, a resistor called a shunt is placed in parallel with the meter. Most of the current flows through the shunt, and only a small fraction flows through the meter. With this solution, arbitrarily large currents can be measured with a single meter. Traditionally, the meter used with a shunt reaches full-scale deflection when a voltage of 50mV is placed across its coil, so shunts are typically designed to produce a voltage drop of 50mV when carrying their full rated current. Resistor symbols (US and Japan) Resistor symbols (Europe, IEC) A pack of resistors A resistor is a two-terminal electrical or electronic component that resists an electric current by producing a voltage drop between its terminals in accordance with Ohms law. ...
In electricity, a shunt is a device which allows electrical current to pass around another point in the circuit. ...
Left: Series / Right: Parallel Arrows indicate direction of current. ...
More modern ammeter designs are non-mechanical, or digital, and use an analog to digital converter to measure the voltage across the shunt resistor. The ADC is read by a microcomputer that performs the calculations to display the current through the resistor. This article or section should include material from AD converters In electronics, an analog-to-digital converter (abbreviated ADC, A/D, or A to D) is a device that converts continuous signals to discrete digital numbers. ...
One problem with the use of an ammeter is the need for the meter to be inserted into the circuit and become part of it. Mistakenly placing the ammeter in parallel with a circuit will blow the fuse, possibly damaging the meter and causing injury. In AC circuits, an inductive coupling adapter converts the magnetic field around a conductor into a small AC current that can be easily read by a meter. See clamp meter. In a similar way, accurate DC non-contact ammeters have been constructed using Hall effect magnetic field sensors. In science and engineering, conductors are materials that contain movable charges of electricity. ...
A clamp meter (clamp-on ammeter) is a type of ammeter which measures electrical current without the need to disconnect the wiring through which the current is flowing. ...
Hall effect diagram, showing electron flow (rather than conventional current). ...
See also
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