Electrical Current Definition

Electrical Current Definition Electrical current is a measure of the amount of electrical charge transferred per unit of time. It represents the flow of electrons through a conductive material, such as a metal wire. It is measured in amperes. Units and Notation for Electrical Current The SI unit of electrical current is the ampere, defined as 1 coulomb/second.  Current is a  quantity, meaning it is the same number regardless of the  direction of the flow, without a positive or negative number. However, in circuit analysis, the direction of current is relevant. The conventional symbol for current is  I, which originates from the French phrase  intensità © de courant, meaning  current intensity.  Current intensity is often referred to simply as  current. The  I  symbol was used by  Andrà ©-Marie Ampà ¨re, after whom the unit of electric current is named. He used the I symbol in formulating  Ampà ¨res force law in 1820.  The notation traveled from France to Great Britain, where it became standard, although at least one journal did not change from using  C  to  I  until 1896. Ohms Law Governing Electrical Current Ohms law states that the current through a conductor between two points is directly  proportional  to the  potential difference  across the two points. Introducing the constant of proportionality, the  resistance, one arrives at the usual mathematical equation that describes this relationship: IV/R In this relationship,  I  is the current through the conductor in units of  amperes,  V  is the potential difference measured  across  the conductor in units of  volts, and  R  is the  resistance  of the conductor in units of  ohms. More specifically, Ohms law states that the  R  in this relation is constant and is independent of the current. Ohms law is used in electrical engineering for solving circuits. The abbreviations  AC  and  DC  are often used to mean simply  alternating  and  direct, as when they modify  current  or  voltage. These are the two main types of electrical current. Direct Current Direct current (DC) is the unidirectional flow of  electric charge. The  electric charge  flows in a constant direction, distinguishing it from  alternating current  (AC). A  term formerly used  for  direct current  was galvanic current. Direct current is produced by sources such as  batteries,  thermocouples,  solar cells, and commutator-type electric machines of the  dynamo  type. Direct current may flow in a  conductor  such as a wire  but can also flow through  semiconductors,  insulators, or even through a  vacuum  as in  electron or ion beams. Alternating Current In alternating current (AC, also ac), the movement of  electric charge  periodically reverses direction. In  direct current, the flow of electric charge is only in one direction. AC is the form of  electric power  delivered to businesses and residences. The usual  waveform  of an  AC power  circuit is a  sine wave. Certain applications use different waveforms, such as  triangular  or  square waves. Audio  and  radio  signals carried on electrical wires are also examples of alternating current. An important goal in these applications is the  recovery of information encoded (or  modulated) onto the AC signal.