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'''SI उपसर्ग''' ('''मीट्रिक उपसर्ग''' भी कहा जाता है) है नाम या जिङा हुआ चिन्ह है, जो कि किसी मापक इकाई के पहले जोङा जाता है, उसे दशमलव का गुणक या उप-गुणक बनाने हेतु । संक्षेपाक्षर ''SI'' फ्रेंच नाम ''Système International d’Unités'' (''[[अन्तर्राष्ट्रीय इकाई प्रणाली]] भी कहा जाता है ). '' SI [[उपसर्ग]] का प्रयोग प्रायः संख्यात्मक तुलनार्थों में शून्यों की मात्रा घटाने हेतु किया जाता है। उदाहरणतः एक एम्पीयर के अरबवें भाग को ''0.000 000 001 एम्पीयर'' लिखा जाता है, जबकि चिन्हात्मक रूप में इसे ''0.000 000 001'' A लिखा जाएगा । परंतु SI उपसर्गों का प्रयोग करते हुए, इस ही को 1 ''नैनो''एम्पीयर या 1 nA लिखेंगे । . SI उपसर्ग तय होते हैं [http://www.bipm.fr/en/home/ Bureau International des Poids et Mesures] (BIPM, जिसे [[International Bureau of Weights and Measures]] भी कहते हैं) ये उत्पाद हैं and are the product of [http://www.bipm.org/en/si/prefixes.html four resolutions| सम्मेलनों ] का जो कि 1960 से 1991 तक हुए ।
== SI उपसर्गों की सूची ==
इस सारणी में बीस SI उपसर्ग दिये गये हैं।
हिऐगेउ एबेगे वोफेइउघ ४ग्व्य्तिव्४त्फ्ग व्तिय्व्४ग्ति वेये उव्व्य्व्य्व व्ग्र्फ्
{{SI prefixes}}
{{मध्य-आधार}}
{{एस आई मापन में प्रयुक्त उपसर्ग}}
== प्रयोग ==
=== उपसर्ग एवं चिन्हों का सामान्य प्रयोग ===
Twenty SI prefixes are available to combine with units of measure. For example, the prefix name ''kilo'' denotes a multiple of one thousand, so 1 [[kilometre]] equals 1000 [[metre]]s, 1 [[kilogram]] equals 1000 [[gram]]s, 1 kilowatt equals 1000 [[watt]]s, and so on. Each SI prefix name has an associated symbol which can be used in combination with the symbols for units of measure. Thus, the “kilo” symbol, k, can be used to produce km, kg, and kW, (kilometre, kilogram, and kilowatt). SI prefixes are internationally recognized and also exist outside the SI (many of them long pre-date SI, going back to the original introduction of the metric system); prefixes may also be used in combination with non-SI units; for example: milligauss (mG), kilofoot (kft) and microinch (µin).
=== अनेक उपसर्गों का उपयोग निषेध ===
The kilogram is the only SI base unit that has an SI prefix as part of its unit name and symbol. Because multiple prefixes may not be used (such as microkilogram or µkg), the prefixes are used with the unit ''gram'' and its symbol ''g'' (e.g. milligram or mg).
=== SI prefixes with symbols for time and angles ===
Officially endorsed policies of the BIPM and the [[[USA|American]]] [[National Institute of Standards and Technology]] (NIST) vary slightly with respect to the use of the SI prefixes—both between their respective agencies and from real-world practice. For instance, the NIST [http://physics.nist.gov/Pubs/SP811/sec06.html advises] that “…to avoid confusion, prefix symbols (and prefixes) are not used with the time-related unit symbols (names) min (minute), h (hour), d (day); nor with the angle-related symbols (names) ° (degree), '''′''' (minute), and '''″''' (second).” The BIPM’s position on the use of SI prefixes with units of time larger than the second is the same as that of the NIST but their position with regard to angles differs: they [http://www.bipm.fr/en/si/si_brochure/chapter3/prefixes.html state] “However astronomers use milliarcsecond, which they denote mas, and microarcsecond, µas, which they use as units for measuring very small angles.”
=== °C के संग SI उपसर्ग °C ===
A similar difference between officially endorsed policy and actual practice exists with regard to the symbol for degree Celsius (°C). The NIST [http://physics.nist.gov/Pubs/SP811/sec06.html states] “Prefix symbols may be used with the unit symbol °C and prefixes may be used with the unit name ‘degree Celsius.’ For example, 12 m°C (12 millidegrees Celsius) is acceptable.” Notwithstanding this official endorsement, the practice of using prefixed forms of “°C” (such as “µ°C”) has not been well-adopted in science and engineering; prefixed forms of the [[kelvin]] are usually used instead.
== ब्यौरा ==
{{Seealso|Non-SI unit prefixes}}
उदाहरण:
* 5 cm = 5 × 10<sup>−2</sup> m = 5 × 0.01 m = 0.05 m
* 3 MW = 3 × 10<sup>6</sup> W = 3 × 1 000 000 W = 3 000 000 W
The prefix always takes precedence over any exponentiation; thus "km²" means ''square kilometre'' and not ''kilo–square metre''. For example, 3 km² is equal to 3 000 000 m² and ''not'' to 3000 m² (''nor'' to 9 000 000 m²). Thus the SI prefixes provide steps of a factor one million instead of one thousand in the case of an exponent 2, of a thousand million in the case of an exponent 3, etc. As a result large numbers may be needed, even if the prefixes are fully used, or intermediate units (like the [[litre]]) are introduced.
Prefixes where the [[exponent]] is divisible by three are often recommended. Hence "100 m" rather than "1 hm".
[[Non-SI unit prefix|Obsolete prefixes]] such as ''[[myrio-]]'' and ''[[myria-]]'', denoting a factor of 10,000 with ''[[grado-]]'' and ''[[grada-]]'', denoting a factor of 100,000<ref>[http://books.google.pl/books?id=h6miHpDMjXEC&pg=PA494The Edinburgh Encyclopedia]</ref> were dropped before SI was adopted in 1960, probably because they did not fit this pattern. One-letter symbols were not available, as ''M'', ''m'', ''µ'' and ''G'', ''g'' were already used, so the two-letter symbols ''mo'', ''ma'' and ''go'', ''ga'' were, albeit rarely, then used instead.
{|class = "wikitable"
|+ Obsolete prefixes
|----- bgcolor=#E8E8FF height=21
! 10<sup>n</sup>
! Prefix
! Symbol
! Decimal
|-----
| 10<sup>5</sup>|| [[grada]]||<center>ga</center>||100 000
|-----
| 10<sup>4</sup>|| [[myria]]||<center>ma</center>||10 000
|-----
| 10<sup>−4</sup>|| [[myrio]]||<center>mo</center>||0.000 1
|-----
| 10<sup>−5</sup>|| [[grado]]||<center>go</center>||0.000 01
|}
The prefix ''kilo'' derives from the [[Greek language|Greek]] word ''χίλια'' (''khilia'' or ''chilia'') = thousand.
Double prefixes such as those formerly used in [[Farad|''micromicrofarads'']] (picofarads), ''hectokilometres'' (100 kilometres), and ''millimicrons'' or ''micromillimetres'' (both nanometres) were also dropped with the introduction of the SI.
Though in principle legal, many combinations of prefixes with quantities are rarely used. In most contexts only a few, i.e. the most common, standard combination are established:
* Mass: hectogram, gram, milligram, microgram, and smaller are common. However, megagram or larger are rarely used; tonnes or [[scientific notation]] are used instead. Megagram is sometimes used to disambiguate the (metric) tonne from the various (non-metric) tons.
* Volume in litres: litre, decilitre, centilitre, millilitre, microlitre, and smaller are common. Larger volumes are sometimes denoted in hectolitres; otherwise in cubic metres or cubic kilometres. In Australia<!-- what about elsewhere? -->, large quantities of water are measured in kilolitres, megalitres and gigalitres.
* Length: kilometre, metre, decimetre, centimetre, millimetre, and smaller are common. The micrometre is often referred to by the non-SI term ''[[Micrometre|micron]]''. In some fields such as [[chemistry]], the [[angstrom]] (equal to 0.1 nm) competes with the nanometre. The [[femtometre]], used mainly in particle physics, is usually called a [[fermi (unit)|fermi]]. At large scales, megametre, gigametre, and larger are rarely used. Often used are [[astronomical unit]]s, [[light year]]s, and [[parsec]]s; the astronomical unit is mentioned in the SI standards as an accepted non-SI unit.
* Time: second, millisecond, microsecond, and shorter are common. The kilosecond and megasecond also have some use, though for these and longer times one usually uses either scientific notation or minutes, hours, and so on.
<sup>†</sup> the United Kingdom, Ireland, Australia and New Zealand previously used the [[long and short scales|long scale]] number name conventions, but have now at least partly switched to the [[long and short scales|short scale]] usage. In particular, above a million and below a millionth, the ''same'' name has different values in the two naming systems, so ''billion'' and ''trillion'' (for example) have unfortunately become potentially ambiguous terms internationally. Using the SI prefixes can circumvent this problem.
== उच्चारण ==
There are two accepted pronunciations for the prefix ''giga-'': {{IPA|[ˈgɪgə]}} and {{IPA|[ˈdʒɪgə]}}. According to the American writer Self, in the 1920s a German committee member of the [[International Electrotechnical Commission]] proposed giga- as a prefix for 10<sup>9</sup>, drawing on a verse by the humorous poet Christian Morgenstern that appeared in the third (1908) edition of ''Galgenlieder'' (Gallows Songs). This suggests a hard German ''g'' was originally intended as the pronunciation. Self was unable to ascertain at what point the {{IPA|/dʒ/}} (soft ''g'') pronunciation became accepted, but as of 1995 current practice had returned to {{IPA|/g/}} (hard ''g'').<ref>{{cite journal
| last = Self
| first = Kevin
| title = Technically speaking
| journal = Spectrum
| pages = 18
| publisher = IEEE
|date=October 1994}}</ref>
<ref>{{cite journal
| last = Self
| first = Kevin
| title = Technically speaking
| journal = Spectrum
| pages = 16
| publisher = IEEE
|date=April 1995}}</ref>
When any SI prefix is affixed to a root word, the prefix carries the primary [[stress (linguistics)|stress]], and the root word carries a secondary stress on the same syllable that is stressed when the root word stands alone. For example, the pronunciation and stress of ''[[gigabyte]]'' is {{IPA|/ˈɡɪɡəbaɪt/}}. However, when a word with an SI prefix is also commonly used outside the scientific community, it may adopt other pronunciations that do not follow this rule. For example, ''kilometre'' (or in the USA, ''kilometer'') may also be pronounced {{IPA|/kɨˈlɑmɨtɚ/}}.
== SI के बाहर प्रयोग ==
The symbol "K" is often used informally to mean a multiple of (a) thousand, so one may talk of "a 40K salary" (40 000), or the [[Year 2000 problem|Y2K problem]]. In these cases an uppercase K is often used, although using an uppercase K is never correct when writing under the rules of the SI. Also, it is often used as a prefix to designate the [[binary prefix]] kilo = 2<sup>10</sup> = 1024, although this is now non-standard.
=== गैर-SI इकाइयाँ ===
<!--note that in this subsection, we are interested in the combination of prefix and unit; if that combination doesn't have an article in Wikipedia, a link to the underlying units (or to the underlying prefixes, for that matter) serves no useful purpose whatsoever -->
* Prefixes go back to the introduction of the [[metric system]] in the 1790s, long before the SI was introduced in 1960. The prefixes (including those introduced after the introduction of SI) are used with any metric units, SI or not (e.g. millidynes).
* SI prefixes rarely appear coupled with [[imperial unit]]s or [[English unit]]s except in some specialised cases (''e.g.'' microinches, kilofeet, kilopound or 'kip').
* They are also used with other specialized units used in particular fields (''e.g.'' megaelectronvolts, gigaparsecs).
* They are also occasionally used with currency units (e.g., gigadollar), mainly by people who are familiar with the prefixes from scientific usage.
=== गणना करना ===
{{main|Binary prefix}}
The prefixes k and greater are common in [[computing]], where they are applied to information and storage units like the [[bit]] and the [[byte]]. Since 2<sup>10</sup> = 1024, and 10<sup>3</sup> = 1000, this led to the SI prefix letters being used to denote "binary" powers. Although these are incorrect usages according to the SI standards it seems common to apply base 10 prefixes, when relating to computer memory, as follows:
; k:= 2<sup>10</sup> = 1 024
; M:= 2<sup>20</sup> = 1 048 576
; G:= 2<sup>30</sup> = 1 073 741 824
; T:= 2<sup>40</sup> = 1 099 511 627 776
; P:= 2<sup>50</sup> = 1 125 899 906 842 624
These prefixes, however, usually retain their powers-of-1000 meanings when used to describe either disk storage or rates of data transmission ([[bit rate]]s): 10 [[Mbit/s]] [[Ethernet]] runs at 10,000,000 bit/s, not 10,485,760 bit/s. The confusion is compounded by the fact that the units of information (the [[bit]] and the [[byte]]) are not part of SI, where the bit, byte, [[octet (computing)|octet]], [[baud]] or [[symbol rate]] would rather be given in [[hertz]].
Although some use "bit" for the [[bit]] and "b" for the [[byte]], "b" is often used for bit and "B" for byte instead. It is recommended by several standards bodies to use '''bit''' and '''B''' to keep the units very distinct, as in ''kbit'' or ''MiB''.{{Facts|date=November 2007}} French-speakers often use "o" for "octet", nowadays a synonym for byte.
Consequently, the [[International Electrotechnical Commission]] (IEC) adopted new [[binary prefix]]es in 1998, formed from the first syllable of the decimal prefix plus 'bi' (pronounced 'bee'). The symbol is the decimal symbol plus 'i'. So now, one [[kilobyte]] (1 kB) equals 1000 bytes, whereas one [[kibibyte]] (1 KiB) equals 2<sup>10</sup> = 1024 bytes. Likewise [[mebi]] (Mi; 2<sup>20</sup>), [[gibi]] (Gi; 2<sup>30</sup>), [[tebi]] (Ti; 2<sup>40</sup>), [[pebi]] (Pi; 2<sup>50</sup>), and [[exbi]] (Ei; 2<sup>60</sup>). Although the IEC standard does not mention them, the sequence can be readily extended to [[zebi]] (Zi; 2<sup>70</sup>) and [[yobi]] (Yi; 2<sup>80</sup>). The practical use of these binary prefixes is growing only very slowly and is largely limited to expert literature. They remain mostly ignored by marketing literature.
== प्रस्तावित बदलाव ==
=== विस्तारण ===
Continuing backwards in the alphabet, after ''zetta'' and ''yotta'', proposals for the next large number include ''xenta'' and ''xona'' (among others), the latter as an alteration of the [[Latin]]-derived [[numerical prefix]] [[Wiktionary:nona-|nona-]], and the next ''small'' number would also start with an ‘x’.{{Fact|date=June 2007}}
One proposed extension is, after ''zetta'' and ''yotta'', ''xona'', ''weka'', ''vunda'', ''uda'', and ''treda''.<ref>Slide 2 on the presentation at http://bt.pa.msu.edu/TM/BocaRaton2006/talks/davis.pdf</ref>
Preserving the rule on abbreviating the prefixes (a [[Latin alphabet|Latin]] capital for the large number and a lower-case letter for the small number), even without consensus on the full name the following prefix symbols could be used without ambiguity: ‘X’, ‘W’, ‘V’, ‘x’, ‘w’, ‘v’. The logically next small prefix symbol, ‘u’, was formerly the accepted substitution for ‘µ’ (now withdrawn), the symbol for “micro”.<ref>{{cite web
|url=http://isotc.iso.org/livelink/livelink/4289384/ISO_2955-1983E_repr_of_SI_units_with_limited_char_sets.pdf?func=doc.Fetch&nodeid=4289384
|title=International Standard ISO 2955: "Information processing - Representation of SI and other units in Systems with limited character sets (2nd ed.)
|accessdate=2006-07-26
|date=1983-05-15
|publisher=International Organization for Standardizaton
|pages=4}}</ref><ref>A search at [http://www.iso.org/iso/en/CatalogueListPage.CatalogueList?scopelist=CATALOGUE http://www.iso.org/iso/en/CatalogueListPage.CatalogueList?scopelist=CATALOGUE] for standard number 2955 shows this standard is withdrawn (accessed 2006-07-26).</ref>
<!-- However, even some official prefixes may not be understood by all readers, let alone extrapolations of them, so giving an explanation is advisable when using them in communication (as opposed to using them in notes for oneself). // should this be here? -->
Another proposal for xenta/xona is ''novetta'', from the Italian [[Wiktionary:nove|nove]]. {{Fact|date=June 2007}} This does not have the convenience of backward alphabetic order. Also, the symbol 'n' is already in use for "nano".
=== Harmonisation ===
There are also proposals for further harmonisation of the capitalisation. Therefore the symbols for kilo, hecto, and deka would be changed from ‘k’ to ‘K’, from ‘h’ to ‘H’, and from ‘da’ to ‘D’. Likewise some lobby for the removal of prefixes that do not fit the 10<sup>±3''n''</sup> scheme, namely hecto, deka, deci, and centi. The [[CGPM]] has postponed its decision on both matters for now.
An unsolved (and maybe unsolvable) issue is the application of prefixes to units with exponents other than ±1. The prefix is always applied before the exponent. This eventually led to the introduction of special units for area and volume without exponents in the original [[metric system]]:
* 1 [[are]] (a) = 100 m² (10 m × 10 m = 1 dam × 1 dam = 1 dam²)
** ⇒ 1 ca = 1 m² (1 m × 1 m)
** ⇒ 1 ha = 10 000 m² (100 m × 100 m = 1 hm × 1 hm = 1 hm²)
* 1 [[stere]] (st) = 1 m³
* 1 [[litre]] (l or L) = 1 dm³ = 1 mst = 0.001 m³
Of these the litre and the hectare are the most ubiquitous in common use: Litre designations are sometimes used to differentiate a volume of liquid (as opposed to a gas, or solid which are usually designated as cubic volumes). Hectares are widely used as a metric alternative to the acre (approximately 2.5 acres to the hectare).
== References ==
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