Current - Revision history

TimVK4YEH: added some info on DC

2009-05-15T21:30:14Z

added some info on DC

← Older revision		Revision as of 14:30, 15 May 2009
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	Current is defined as the time rate of change of charge. This means that current is the quantity of electric charge that passes a point on the conductor per second.		Current is defined as the time rate of change of charge. This means that current is the quantity of electric charge that passes a point on the conductor per second.

	For an electric current of 1 ampere, 1 '''coulomb''' of electric charge (which consists of about 6.242 × 10<sup>18</sup> electrons) drifts every second ~~through~~ any ~~plane through which the~~ conductor ~~passes~~.		For an electric current of 1 ampere, 1 '''coulomb''' of electric charge (which consists of about 6.242 × 10<sup>18</sup> electrons) drifts every second past any point on a conductor.

	For a steady flow, the current ''I'' in amperes can be calculated with the following equation:		For a steady flow, the current ''I'' in amperes can be calculated with the following equation:
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	For example, in a copper wire of cross-section 0.5 mm<sup>2</sup>, carrying a current of 5 A, the ''drift speed'' of the electrons is of the order of a millimetre per second.		For example, in a copper wire of cross-section 0.5 mm<sup>2</sup>, carrying a current of 5 A, the ''drift speed'' of the electrons is of the order of a millimetre per second.

	===Direct and Alternating Current ===		==Direct and Alternating Current ==

			=== Direct Current===

			'''Direct Current - DC''' is the flow of electric charge through a conductor in one direction. Common sources of DC are batteries, thermocouples and solar cells. Many circuits are designed to operate on DC. These circuits will usually either not operate at all or be damaged if the DC is applied in the wrong direction.

			Direct current can also mean "constant polarity current". In this, the current can vary, but its direction does not change.

			=== Alternating Current===
	External links:		External links:

TimVK4YEH: /* How is current measured? */

2009-05-15T21:00:53Z

How is current measured?

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 In simple circuis the answer is no. Many circuits however contain "polarised" components that only work properly if they are placed in the circuit in a particulat orientation. One example is the [[Diodes | diode]]. Polarised devices are usually [http://www.howstuffworks.com/diode.htm semiconductors] but do include electrolytic capacitors.
-==How is current measured?==
+==How is current created?==
 ===Direct and Alternating  Current ===

TimVK4YEH: started dirct and alternating current - more to follow

2009-04-16T06:47:42Z

started dirct and alternating current - more to follow

← Older revision		Revision as of 23:47, 15 April 2009
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			===Direct and Alternating Current ===
	External links:		External links:

TimVK4YEH: /* Does it matter which one we use? */

2009-04-16T06:37:32Z

Does it matter which one we use?

← Older revision		Revision as of 23:37, 15 April 2009
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	===Does it matter which one we use?===		===Does it matter which one we use?===

	In simple circuis the answer is no. Many circuits however contain "polarised" components that only work properly if they are placed in the circuit in a particulat orientation. One example is the [[Diodes \| diode]]. Polarised devices are usually [http://www.howstuffworks.com/diode.htm semiconductors]		In simple circuis the answer is no. Many circuits however contain "polarised" components that only work properly if they are placed in the circuit in a particulat orientation. One example is the [[Diodes \| diode]]. Polarised devices are usually [http://www.howstuffworks.com/diode.htm semiconductors] but do include electrolytic capacitors.

	==How is current measured?==		==How is current measured?==

Carlb: /* How is current measured? */

2009-04-09T01:16:51Z

How is current measured?

← Older revision		Revision as of 18:16, 8 April 2009
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	* [http://en.wikipedia.org/wiki/Electric_current wikipedia article]		* [http://en.wikipedia.org/wiki/Electric_current wikipedia article]


			{{electronics}}

TimVK4YEH: added brief info

2008-10-25T00:34:56Z

added brief info

← Older revision		Revision as of 17:34, 24 October 2008
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	== What is current? ==		== What is current? ==

			Simply, current is the flow of electric charge through a conductor.

			===Conventional Current===

			The notion of conventional current was started by Bejamin Franklin who sought to decribe the phenomenon of static electricity saying that charge (electrons) could be "rubbed off" some materials by others. He proposed that charge was transferred from wax to wool when they are rubbed together. He described the wool as being "negative" or having a deficiency of charge which allowed the transfer to take place. These experiments occurred well before the nature of electrons was dicovered, by which time his descriptions had taken a firm hold in the scientific community.

			Hence, conventional current is said to flow from positive to negative.

			=== Electron Flow Current===

			We now know that electrons carry an negative charge, and that similar charges repel. Hence, in an electic circuit, negative charge (and electrons) will move from the more negative end of the circuit to the more positive.

			===Does it matter which one we use?===

			In simple circuis the answer is no. Many circuits however contain "polarised" components that only work properly if they are placed in the circuit in a particulat orientation. One example is the [[Diodes \| diode]]. Polarised devices are usually [http://www.howstuffworks.com/diode.htm semiconductors]

	==How is current measured?==		==How is current measured?==

TimVK4YEH: started current page

2008-10-24T08:16:47Z

started current page

New page

Related wiki pages: [[Voltage]], [[Resistance]]

== What is current? ==

==How is current measured?==

External links:

* [http://en.wikipedia.org/wiki/Electric_current wikipedia article]