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.

Electrical components, like motors close motorA device which spins when current flows through it. Motors are used in fans, food processors and many other devices. and lamps close lampA component which ...

A general method for measuring AC high voltages is to use a voltage divider, with two resistors in series. The resistors are selected so across one of the elements is some arbitrary fraction (like ...