The simplest complete circuit is a piece of wire from one end of a battery to the other. An electric current can flow in the wire from one end of the battery to the other, but nothing useful happens.

Current is a measure of how much electric charge flows through a circuit. The more charge that flows, the bigger the current. Current is measured in amperes. The symbol for ampere is A. For example, ...

Upon configuring a PMMC (Permanent Magnet Moving Coil) as an ammeter, a shunt resistor is connected to it, to adjust the range of measurement. The value of the shunt resistor depends on the current ...