Electrodynamics is the study of the relationship between electric, magnetic, and mechanical phenomena.

A stationary charged particle has an electric field associated with it. When the charged particle is put in motion a magnetic field is established. These fields have forces that can do work or cause effects on other objects nearby. Accordingly, the study of electrodynamics is concerned with charges in motion.

The flow of electric charges constitutes an electric current. In order to move charges in a conductor, an electromotive driving force is required. This electromotive force, also known as an electrical potential difference, with a conductor connected across the device's two terminals constitutes a circuit. There are two types of current: direct current and alternating current. Direct current is a flow of charge and therefore current in one direction at a constant rate. Alternating current is a flow of current that increases in magnitude from...