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The most important electronics terms, demystified in one place.


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Current is the measurement of electron movement. The unit of measurement is ampere, almost always referred to as an amp, and is established as one coulomb moving past a specific point per second. As it is the movement of electrons, you say that current flows "through" an object or device.

Book Definition

The time rate of change of charge, measured in amperes.

Fundamentals of Electric Circuits, 5th Edition by Charles K. Alexander and Matthew N. O. Sadiku

A movement of electric charges around a closed path or circuit.

Grob’s Basic Electronics, 11th Edition by Mitchel E. Schultz

The rate of flow of electrical charge.

Electronic Devices : Conventional Current Version, 9th Edition by Thomas L. Floyd


An electric current is the rate of flow of electric charge past a point[1]:2[2]:622 or region.[2]:614 An electric current is said to exist when there is a net flow of electric charge through a region.[3]:832 In electric circuits this charge is often carried by electrons moving through a wire. It can also be carried by ions in an electrolyte, or by both ions and electrons such as in an ionized gas (plasma).[4]

The SI unit of electric current is the ampere, which is the flow of electric charge across a surface at the rate of one coulomb per second. The ampere (symbol: A) is an SI base unit[5]:15 Electric current is measured using a device called an ammeter.[2]:788

Electric currents cause Joule heating, which creates light in incandescent light bulbs. They also create magnetic fields, which are used in motors, inductors and generators.

The moving charged particles in an electric current are called charge carriers. In metals, one or more electrons from each atom are loosely bound to the atom, and can move freely about within the metal. These conduction electrons are the charge carriers in metal conductors.

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