What is an Ammeter?
Ammeters are used to measure the current in electricity in amperes, also called amps. Named after French scientist Andre-Marie Ampere, amperes are a unit of measurement for determining the amount of electricity moving through a circuit. Ampere's Law basically states that the magnetic field within a closed loop, or circuit, is proportional to the electric current in that loop. Ammeters used to measure smaller currents have different names. Those that measure milliamperes are called milliammeters. Those that measure currents in the microampere range are called microammeters.
How Ammeters Work
Ammeters are used to measure electrical current by having the current move through a set of coils. In moving-coil ammeters, this movement results from the fixed magnets that are set opposite to the current. The movement then turns a centrally located armature that is attached to an indicator dial. This dial is set above a graduated scale that lets the operator know how much current is moving through a closed circuit.
Types of Ammeters
There are various types of ammeters. The d'Arsonval ammeter uses a fixed magnet and a galvanometer through which an electric current passes. Ammeters used to measure high frequency currents utilize the heat created by the electrical current that moves through the coils. The heat is detected by thermocouples, which helps drive a moving-coil indicator.
Uses for Ammeters
Ammeters have various applications where they can be used to read alternating current, or AC, as well as direct current, or DC. Ammeters can be found in cars, where they measure DC electricity. Ammeters and voltemeters are often manufactured as a single instrument, which digitally displays current measurements with very high degree of accuracy.