CURRENT [DC]

==Current== Electrical current is the flow of charge through a circuit. It is defined as the number of coulombs (1 Coulomb = 6.25 x 10^18^ electrons) of charge passing a point per second. Electric current has the symbol '''I''' and the unit '''A''' (Amps). It has the equation, I = Q/t. E.g. I = 4.2 A [image:http://i.imgur.com/LnliTwx.png] Even though in a metal it is the electrons that are forced to flow, '''conventional current''' is drawn as flowing from positive (high potential) to negative (low potential). Electrical current is measured in amperes (A), by an ammeter. [image:http://i.imgur.com/ThyPVOW.gif] An ammeter simply measures how much charge is passing through a given point in the circuit each second. It is like standing beside a river and measuring how much water passes by each second. Because there are far too many water particles and they are far too small, you would probably describe the current in litres per second. In the same way, there are far too many electrons to count so we count groups / packets of electrons called coulombs. One ampere means there is a current of 1 coulomb (6,250,000,000,000,000,000 electrons) passing a point per second. *Note that a complete circuit is required before the electrons will flow.