en>Bgwhite: Do general fixes and cleanup. - using AWB (9421)

2013-08-16T06:53:53Z

Do general fixes and cleanup. - using AWB (9421)

← Older revision		Revision as of 08:53, 16 August 2013
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	~~Irwin Butts~~ is ~~what my spouse loves~~ to ~~call me although I don~~'~~t really like being known~~ as ~~like that~~. ~~Hiring has been my profession for some time but I~~'~~ve currently applied~~ for ~~an additional one~~. ~~Minnesota~~ is ~~where he~~'s ~~been residing for years~~. The ~~favorite pastime for my kids~~ and me is to ~~play baseball~~ and ~~I'm attempting~~ to ~~make it~~ a ~~occupation~~.<br><br>~~Check out my weblog~~ :: [http://www.~~pornextras~~.~~info~~/~~user~~/~~FBrinker~~ www.~~pornextras~~.~~info~~]		A practical electrical power source which is a linear electric circuit may, according to [[Thévenin's theorem]], be represented as an [[ideal voltage source]] in series with an [[Electrical impedance\|impedance]]. This resistance is termed the '''internal resistance''' of the source. When the power source delivers [[Electric current\|current]], the measured [[Electromotive force\|e.m.f.]] (voltage output) is lower than the no-[[electrical load\|load]] voltage; the difference is the voltage (the [[Ohm's law\|product of current and resistance]]) drop caused by the internal resistance. The concept of internal resistance applies to all kinds of electrical sources and is useful for analyzing many types of electrical circuits. Internal resistance can be caused by a number of outcomes, though a possible cause is by interior chemical installment. When thermal energy is applied to provide the current, that applied energy is most of the power source's energy which produces the chemicals. The load current is delivered in a lap and returns to the battery (voltage source) and then performs resistance.

			== Batteries ==
			[[Battery (electricity)\|Batteries]] can be approximately modeled as a voltage source in series with a resistance. The internal resistance of a battery is dependent on the specific battery's size, chemical properties, age, temperature and the discharge current. It has an electronic component due to the resistivity of the battery's component materials and an ionic component due to electrochemical factors such as electrolyte conductivity, ion mobility, and electrode surface area. Measurement of the internal resistance of a battery is a guide to its condition, but may not apply at other than the test conditions. Measurement with an [[alternating current]], typically at a frequency of 1kHz, may underestimate the resistance, as the frequency may be too high to take into account the slower electrochemical processes. Internal resistance depends upon temperature; for example, a fresh [[Energizer]] [[AA battery\|E91 AA]] alkaline primary battery drops from about 0.9 ohms at -40 °C, where the low temperature reduces ion mobility, to about 0.15 ohms at room temperature and about 0.1 ohms at 40 °C.<ref name=energizer>{{cite web\|url=http://data.energizer.com/PDFs/BatteryIR.pdf\|work=Energizer Technical Bulletin\|publisher=[[Energizer Battery]]\|title=Battery Internal Resistance\|date=200512}}</ref>

			The internal resistance of a battery can be calculated from its open circuit voltage, voltage on-load, and the load resistance:
			<math> R_{\text{int}} = ({\frac{ V_{\text{NL}} } { V_{\text{FL}} } - 1 } ) { R_{\text{L}} } </math>

			Many [[ESR meter\|equivalent series resistance (ESR) meters]], essentially AC milliohmmeters normally used to measure the ESR of capacitors, can be used to estimate battery internal resistance, particularly to check the state of discharge of a battery rather than obtain an accurate dc value.<ref>[http://www.flippers.com/esrkthnt.html#battery Testing batteries with ESR meter]</ref> Some chargers for rechargeable batteries indicate the ESR.

			In use the voltage across the terminals of a disposable battery driving a load decreases until it drops too low to be useful; this is largely due to an increase in internal resistance rather than a drop in the voltage of the equivalent source.

			With rechargeable [[lithium polymer]] batteries the internal resistance is largely independent of the state of charge, but increases as the battery ages, thus is a good indicator of expected life.<ref>[http://www.rchelicopterfun.com/rc-lipo-batteries.html Understanding RC LiPo Batteries]</ref><ref>[http://www.progressiverc.com/media/ESR%20Meter%20Instructions.pdf ESR Meter For 2 – 6 Cell Lipo Packs - instructions]</ref>

			==See also==
			*[[Norton's theorem]]

			==References==

			<references/>
			* Student Reference Manual for Electronic Instrumentation Laboratories (2nd Edition) - Stanley Wolf & Richard F.M. Smith

			* Fundamentals of Electric Circuits (4th Edition) - Charles Alexander & Matthew Sadiku

			== External links ==
			*[http://www.sengpielaudio.com/calculator-voltagebridging.htm Interconnection of two audio units - Output impedance and input impedance]

			{{DEFAULTSORT:Internal Resistance}}
			[[Category:Electronics]]

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en>HotdogPi: Relations to triangular numbers

2012-07-07T00:02:12Z

Relations to triangular numbers

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Irwin Butts is what my spouse loves to call me although I don't really like being known as like that. Hiring has been my profession for some time but I've currently applied for an additional one. Minnesota is where he's been residing for years. The favorite pastime for my kids and me is to play baseball and I'm attempting to make it a occupation.<br><br>Check out my weblog :: [http://www.pornextras.info/user/FBrinker www.pornextras.info]

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en>Bgwhite: Do general fixes and cleanup. - using AWB (9421)

en>HotdogPi: Relations to triangular numbers