Electric current

An electric current is a flow of charged particles, such as electrons or ions, through an electrical conductor or space. It is defined as the net rate at which electric charge flows through a surface. The moving particles are called charge carriers, which may be of several types, depending on the conductor. In electric circuits, the charge carriers are often electrons moving through a wire. In semiconductors, the charge carriers can be electrons or holes. In an electrolyte, the charge carriers are ions, while in plasma- an ionized gas- they are also ions and electrons.

In the International System of Units (SI), electric current is expressed in units of ampere (sometimes called an "amp", symbol A), which is equivalent to one coulomb per second. The ampere is an SI base unit and electric current is a base quantity in the International System of Quantities (ISQ). Electric current is also known as amperage and is measured using a device called an ammeter.

Electric currents create magnetic fields, which are used in motors, generators, inductors, and transformers. In ordinary conductors, they cause Joule heating, which creates light in incandescent light bulbs. Time-varying currents emit electromagnetic waves, which are used in telecommunications to broadcast information.