|
|
| Line 1: |
Line 1: |
| [[Category:Done 2017-07-01]] | | [[Category:Done 2026-08-01]] |
| <onlyinclude>'''Current''' is the amount of [[electric charge]] flowing per [[second]] within a [[conductor]]. It is what carries the [[electric power]] from [[power plant]]s, through the [[electrical transmission|transmission system]] and [[distribution system]] for [[industrial electricity use|industrial]] and [[Connecting homes to the electrical grid|home electricity use]]. It is otherwise known as [[electricity]].</onlyinclude> The intensity of current is determined by the amount of charge flowing per second and is measured in [[ampere]]s, abbreviated as A or amp. When electric charge flows in one direction it's called [[direct current]] and when the electric charge wiggles back and forth, alternating directions, it's called [[alternating current]]. | | <onlyinclude>Current can mean either: |
| | * [[Electric current]] |
| | * Moving water like the current in a river or even ocean |
|
| |
|
| The amount of direct current can be calculated from the following formula: | | The different definitions are related. Many scientists have modelled electricity as the flow of a [[fluid]]. |
| | |
| <math>I=\frac{\Delta Q}{\Delta t}</math>
| |
|
| |
| :<math>I</math> = current in [[ampere]]s,
| |
| :<math>\Delta Q</math> = the [[charge]] in [[coulomb]]s flowing past a given place and
| |
| :<math>\Delta t</math> = the elapsed time in [[second]]s.
| |
| | |
| However coulombs of charge cannot be directly measured, usually a device known as a [[multimeter]] is used to measure current. Alternating current uses a similar equation to determine the amount of current, but the math becomes a little trickier since the direction of moving charge changes rapidly.
| |
| | |
| By convention, the term current (also referred to as conventional current) is defined by the charges moving from the positive terminal to the negative terminal. There also exists the term [[electron]] flow that is used to define charges moving from the negative terminal to the positive terminal. Please note that these are opposites. Conventional current is more popular, though either term may be used so long as this is done consistently to avoid any confusion. For a popular webcomic on how positive and negative charges are defined please visit [http://xkcd.com/567/ XKCD].
| |
| | |
| Whenever current moves through a component or circuit, some [[energy]] is lost to [[heat]]. Some specific applications, toasters for example, make use of this heat. Often this heat is an inefficiency of the system, like in [[electrical transmission#Reducing Power Line Losses|electrical transmission]]. Excess heat can be a real nuisance in some applications like desktop computers that tend to overheat and require fans that [[convection|circulate air]] to keep them cool.
| |
| | |
| [[Switch]]es are used to turn current off (or on) almost instantly, as soon as the charge lacks a place to go (remember, current only moves when there's a full [[circuit]]) the current stops. If too much current starts to flow a special type of switch acts as an emergency safety measure to automatically shut off the current. These emergency safety measures include [[fuse]]s and [[circuit breaker]]s.
| |
| | |
| ===Current and magnetic fields===
| |
| Electric current gives rise to [[magnetic field]]s, as discovered by Hans Øersted in 1819 and soon after expanded upon by André-Marie Ampère,<ref name=magfields>Nuffield Foundation. (Accessed Sept. 3, 2015). ''Oersted, electric current and magnetism'' [Online], Available: http://www.nuffieldfoundation.org/practical-physics/oersted-electric-current-and-magnetism</ref> Jean-Baptiste Biot and Félix Savart to form the first laws of [[electromagnetic force|electromagnetism]].<ref name=biosav> R. Nave. (2015, June. 21) Online. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/biosav.html</ref> [[Electric motor]]s are a common application of this phenomena, using currents and their magnetic fields to convert [[electrical energy]] to [[mechanical energy]].
| |
| | |
| To learn about the physics of electric current please see [http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elecur.html#c1 hyperphysics].
| |
| | |
| ==References==
| |
| {{reflist}}
| |
| [[Category:Uploaded]]
| |
Current can mean either:
The different definitions are related. Many scientists have modelled electricity as the flow of a fluid.
