Ammeters are used to measure the current in electricity in amperes, also called amps. 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.