एम्पियर का स्रोत देखें

[[चित्र:Galvanometer 1890 drawing.png|thumb|200px|विद्युत धारा को गैल्वैनोमीटर के द्वारा मापा जा सकता है। वैसे इसको मापने का सही उपकरण है एम्मीटर]]

'''एम्पीयर''', लघु रूप में '''amp''', (चिन्ह: A) [[विद्युत धारा]], या [[विद्युत आवेश]] अथवा विधुत तरंग की मात्रा प्रति [[सेकेंड|सैकण्ड]]; की इकाई है। एम्पीयर [[मूल इकाइयाँ|SI मूल इकाई]] है और इसका नाम [[विद्युत्चुम्बकत्व|विद्युतचुम्बकत्व]] को खोजने वाले वैज्ञानिक [[:en:André-Marie Ampère|आंद्रे-मैरी एम्पीयर]] के नाम पर रखा गया है।

== परिभाषा ==
{{विद्युतचुम्बकत्व3|edyn=true}}

एम्पीयर वह स्थिर धारा है, जिसे यदि दो असीमित लम्बाई के समानांतर चालकों में रखा जाये, जिनका नगण्य अनुप्रस्थ क्षेत्रफ़ल हो और निर्वात में एक मीटर की दूरी पर स्थित हों; तो इन चालकों में 2×10<sup>–7</sup> [[न्यूटन (इकाई)|न्यूटन]] प्रति मीटर का बल उत्पन्न करे।<ref>Paul M. S. Monk, ''Physical Chemistry: Understanding our Chemical World'', John Wiley and Sons, 2004 [http://books.google.com/books?vid=ISBN0471491802&id=LupAi35QjhoC&pg=PA16&lpg=PA16&ots=IMiGyIL-67&dq=ampere+definition+si&sig=9Y0k0wgvymmLNYFMcXodwJZwvAM online] {{Webarchive|url=https://web.archive.org/web/20110722013657/http://books.google.com/books?vid=ISBN0471491802&id=LupAi35QjhoC&pg=PA16&lpg=PA16&ots=IMiGyIL-67&dq=ampere+definition+si&sig=9Y0k0wgvymmLNYFMcXodwJZwvAM |date=22 जुलाई 2011 }}.</ref>
एम्पीयर [[मूल इकाइयाँ|SI मूल इकाई]] है, जैसे कि [[मीटर]], [[केल्विन|कैल्विन]], [[सेकेंड|सैकण्ड]], [[मोल (इकाई)|मोल]], [[कैंडिला|कैण्डेला]] और [[किलोग्राम]]। इसको [[विद्युत आवेश]] की मत्रा के सन्दर्भ के बिना ही परिभाशःइत किया गया है। आवेश की इकाई [[कूलम्ब]] वह व्युत्पन्न इकाई है। इसकी परिभाषा अनुसार, वह आवेश की मात्रा, जो कि एक एम्पीयर धारा द्वारा एक [[सेकेंड|सैकण्ड]] में विस्थापित किया गया हो। 

परिणामतः, विद्युत धारा, विद्युत आवेश के विस्थापन की दर को कहते हैं। एक एम्पीयर का अर्थ है एक कूलम्ब धारा प्रति सैकण्ड का विस्थापन।

:<math>\mathrm{1 \,A= 1 \frac{\,C}{s}} \,</math>
{{-}}

== व्याख्या ==
<!-- Because it is a base unit, the definition of the ampere is not tied to any other electrical unit. The definition for the ampere is equivalent to fixing a value of the [[Permeability (electromagnetism)|permeability]] of vacuum to ''μ''<sub>0</sub> = 4π×10<sup>−7</sup> H/m. Prior to 1948, the so-called "international ampere" was used, defined in terms of the [[electrolysis|electrolytic]] deposition rate of [[silver]].<ref>Robert B. Northrop, ''Introduction to Instrumentation and Measurements'', CRC Press, 1997 [http://books.google.com/books?vid=ISBN0849378982&id=mcpcfpQfxB4C&pg=PA21&lpg=PA21&ots=ZTUUMNAShz&dq=ampere+1948+electrolytic++silver+international&sig=1Xv1-zsZ1pNuQuFjRzlhJaCWXiY online]</ref> The older unit is equal to 0.999&nbsp;85&nbsp;A.

The ampere is most accurately realized using a [[watt balance]], but is in practice maintained via [[Ohm's Law]] from the units of [[EMF]] and [[electrical resistance|resistance]], the [[volt]] and the [[Ohm (unit)|ohm]], since the latter two can be tied to physical phenomena that are relatively easy to reproduce, the [[Josephson junction]] and the [[quantum Hall effect]], respectively.

The unit of [[electric charge]], the [[coulomb]], is defined in terms of the ampere: one coulomb is the amount of electric charge (formerly [[quantity of electricity]]) carried in a current of one ampere flowing for one [[second]].<ref>Kuzman Ražnjević, ''Physical Quantities and the Units of the International System (Si)'', Begell House Publishers, 1995 [http://books.google.com/books?vid=ISBN1567000479&id=Dhd7jxDk0hIC&pg=PA64&lpg=PA64&ots=_A07F0tdP7&dq=ampere+%22International+Committee+for+Weights+and+Measures%22&sig=gPjXB1DK78FWSnTZVpwnifIktZY#PPA107,M1 online]</ref> [[Current (electricity)|Current]], then, is the rate at which charge flows through a wire or surface. One ampere of current (I) is equal to a flow of one [[coulomb]] of charge (Q) per second of time (t):

:<math>\mathrm{I=Q/t} \,</math> -->

== प्रस्तावित भविष्य परिभाषा ==
<!-- Since a coulomb is approximately equal to 6.24150948×10<sup>18</sup> [[elementary charge]]s, one ampere is approximately equivalent to 6.24150948×10<sup>18</sup> elementary charges, such as [[electron]]s, moving past a boundary in one second.

As with other [[SI]] base units, there have been proposals to redefine the [[kilogram]] in such a way as to define some presently measured [[physical constants]] to fixed values. One proposed definition of the kilogram is: 

{{cquote|The kilogram is the mass which would be accelerated at precisely'' 2×10<sup>-7</sup> m/s<sup>2</sup> ''if subjected to the per metre force between two straight parallel conductors of infinite length, of negligible circular cross section, placed 1 metre apart in vacuum, through which flow a constant current of exactly'' 6 241 509 479 607 717 888 ''elementary charges per second.}}
 
This redefinition of the kilogram has the effect of fixing the [[elementary charge]] to be ''e'' = 1.60217653{{e|-19}} [[coulomb|C]] and would result in a functionally equivalent definition for the [[coulomb]] as being the sum of exactly 6 241 509 479 607 717 888 elementary charges and the ampere as being the electrical current of exactly 6 241 509 479 607 717 888 elementary charges per second. This is consistent with the current 2002 CODATA value for the elementary charge which is 1.60217653×10<sup>-19</sup> ± 0.00000014×10<sup>-19</sup> C. -->

=== CIPM की अनुशंसा ===
<!-- [[International Committee for Weights and Measures]] (CIPM) Recommendation 1 (CI-2005):
Preparative steps towards new definitions of the [[kilogram]], the ampere, the
[[kelvin]] and the [[mole (unit)|mole]] in terms of fundamental constants

The International Committee for Weights and Measures (CIPM),
* approve in principle the preparation of new definitions and mises en pratique of the kilogram, the ampere and the kelvin so that if the results of experimental measurements over the next few years are indeed acceptable, all having been agreed with the various Consultative Committees and other relevant bodies, the CIPM can prepare proposals to be put to Member States of the Metre Convention in time for possible adoption by the 24th [[General Conference on Weights and Measures|CGPM]] in 2011;
* give consideration to the possibility of redefining, at the same time, the mole in terms of a fixed value of the Avogadro constant;
* prepare a Draft Resolution that may be put to the 23rd [[General Conference on Weights and Measures|CGPM]] in 2007 to alert Member States to these activities; -->

{{SI इकाई छोटे|आन्द्रे मैरी एम्पीयर|एम्पीयर|A}}

== देखें ==
* [[अन्तरराष्ट्रीय मात्रक प्रणाली|SI]]
* [[ओम का नियम|ओह्म का नियम]]
* [[विद्युत स्पर्शाघात|बिजली का झटका]] 
* [[एम्पीयर का नियम]]
* [[अमीटर|एमीटर]]
* [[कूलम्ब]]
{{इकाइयाँ}}

== सन्दर्भ ==
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{{reflist}}

== बाहरी कड़ियाँ ==
* [https://web.archive.org/web/20131014073417/http://physics.nist.gov/cuu The NIST Reference on Constants, Units, and Uncertainty]
* [https://web.archive.org/web/20020214114359/http://alpha.montclair.edu/~kowalskiL/SI/SI_page.html A short history of the SI units in electricity]

[[श्रेणी:SI मूल इकाइयाँ]]
[[श्रेणी:विद्युत धारा की इकाइयाँ]]