946:
definition), and the CGS unit. Although called "legal", this standard was not adopted by any national legislation. The "international" ohm was recommended by unanimous resolution at the
International Electrical Congress 1893 in Chicago. The unit was based upon the ohm equal to 10 units of resistance of the C.G.S. system of electromagnetic units. The international ohm is represented by the resistance offered to an unvarying electric current in a mercury column of constant cross-sectional area 106.3 cm long of mass 14.4521 grams and 0 °C. This definition became the basis for the legal definition of the ohm in several countries. In 1908, this definition was adopted by scientific representatives from several countries at the International Conference on Electric Units and Standards in London. The mercury column standard was maintained until the 1948
570:
237:
38:
565:{\displaystyle \Omega ={\dfrac {\text{V}}{\text{A}}}={\dfrac {1}{\text{S}}}={\dfrac {\text{W}}{{\text{A}}^{2}}}={\dfrac {{\text{V}}^{2}}{\text{W}}}={\dfrac {\text{s}}{\text{F}}}={\dfrac {\text{H}}{\text{s}}}={\dfrac {\text{Wb}}{\text{C}}}={\dfrac {{\text{J}}{\cdot }{\text{s}}}{{\text{C}}^{2}}}={\dfrac {{\text{kg}}{\cdot }{\text{m}}^{2}}{{\text{s}}{\cdot }{\text{C}}^{2}}}={\dfrac {\text{J}}{{\text{s}}{\cdot }{\text{A}}^{2}}}={\dfrac {{\text{kg}}{\cdot }{\text{m}}^{2}}{{\text{s}}^{3}{\cdot }{\text{A}}^{2}}}}
852:
force between two unit charges. This latter method ensures coherence with the units of energy. Defining a unit for resistance that is coherent with units of energy and time in effect also requires defining units for potential and current. It is desirable that one unit of electrical potential will force one unit of electric current through one unit of electrical resistance, doing one unit of work in one unit of time, otherwise, all electrical calculations will require conversion factors.
208:
2433:
844:
measurement for resistance. Resistance was often expressed as a multiple of the resistance of a standard length of telegraph wires; different agencies used different bases for a standard, so units were not readily interchangeable. Electrical units so defined were not a coherent system with the units for energy, mass, length, and time, requiring conversion factors to be used in calculations relating energy or power to resistance.
945:
ohm, a reproducible standard, was defined by the international conference of electricians at Paris in 1884 as the resistance of a mercury column of specified weight and 106 cm long; this was a compromise value between the B. A. unit (equivalent to 104.7 cm), the
Siemens unit (100 cm by
1464:
points out that there are three cases in which the final vowel of an SI prefix is commonly omitted: megohm (not megaohm), kilohm (not kiloohm), and hectare (not hectoare). In all other cases in which the unit name begins with a vowel, both the final vowel of the prefix and the vowel of the unit name
1196:
The mercury column method of realizing a physical standard ohm turned out to be difficult to reproduce, owing to the effects of non-constant cross section of the glass tubing. Various resistance coils were constructed by the
British Association and others, to serve as physical artifact standards for
863:
The absolute-unit system related magnetic and electrostatic quantities to metric base units of mass, time, and length. These units had the great advantage of simplifying the equations used in the solution of electromagnetic problems, and eliminated conversion factors in calculations about electrical
851:
cell, could be specified as producing defined quantities for resistance, voltage, and so on. Alternatively, the electrical units can be related to the mechanical units by defining, for example, a unit of current that gives a specified force between two wires, or a unit of charge that gives a unit of
915:
to report upon standards of electrical resistance. Their objectives were to devise a unit that was of convenient size, part of a complete system for electrical measurements, coherent with the units for energy, stable, reproducible and based on the French metrical system. In the third report of the
843:
The rapid rise of electrotechnology in the last half of the 19th century created a demand for a rational, coherent, consistent, and international system of units for electrical quantities. Telegraphers and other early users of electricity in the 19th century needed a practical standard unit of
1276:. It is used in many instances where the value has a decimal place. For example, 5.6 Ω is listed as 5R6, or 2200 Ω is listed as 2K2. This method avoids overlooking the decimal point, which may not be rendered reliably on components or when duplicating documents.
859:
of the relations between potential, current, and resistance show that resistance is expressed in units of length per time – a velocity. Some early definitions of a unit of resistance, for example, defined a unit resistance as one quadrant of the Earth per second.
953:
By the end of the 19th century, units were well understood and consistent. Definitions would change with little effect on commercial uses of the units. Advances in metrology allowed definitions to be formulated with a high degree of precision and repeatability.
884:. However, this unit was not coherent with other units. One proposal was to devise a unit based on a mercury column that would be coherent – in effect, adjusting the length to make the resistance one ohm. Not all users of units had the resources to carry out
787:
A linear resistor has a constant resistance value over all applied voltages or currents; many practical resistors are linear over a useful range of currents. Non-linear resistors have a value that may vary depending on the applied voltage (or current). Where
1197:
the unit of resistance. The long-term stability and reproducibility of these artifacts was an ongoing field of research, as the effects of temperature, air pressure, humidity, and time on the standards were detected and analyzed.
1486:
1208:
has been used to define the ohm with high precision and repeatability. The quantum Hall experiments are used to check the stability of working standards that have convenient values for comparison.
792:
is applied to the circuit (or where the resistance value is a function of time), the relation above is true at any instant, but calculation of average power over an interval of time requires
760:
1485:(NIST), Physical Measurement Laboratory. 2016-08-25 . Chapter 9: Rules and Style Conventions for Spelling Unit Names, 9.3: Spelling unit names with prefixes. Special Publication 811.
923:
The B.A. ohm was intended to be 10 CGS units but owing to an error in calculations the definition was 1.3% too small. The error was significant for preparation of working standards.
1246:
to render the character Ω. Where the font is not supported, the same document may be displayed with a "W" ("10 W" instead of "10 Ω", for instance). As W represents the
2077:
903:
meeting suggesting that standards for electrical units be established and suggesting names for these units derived from eminent philosophers, 'Ohma', 'Farad' and 'Volt'. The
1509:
Aubrecht II, Gordon J.; French, Anthony P.; Iona, Mario (2012-01-20). "About the
International System of Units (SI) Part IV. Writing, Spelling, and Mathematics".
1239:
in 1867. In documents printed before Second World War the unit symbol often consisted of the raised lowercase omega (ω), such that 56 Ω was written as 56.
618:
In many cases the resistance of a conductor is approximately constant within a certain range of voltages, temperatures, and other parameters. These are called
938:
units, using a mercury column 1 mm in cross-section, approximately 104.9 cm in length at 0 °C, similar to the apparatus suggested by
Siemens.
2060:
1953:
An
Electrical Congress was held in Chicago, U.S.A. in August 1893, to consider......and at the last one held in London in October 1908 were finally adopted
1478:
904:
900:
181:
1204:
experiments relating accurately dimensioned inductors and capacitors provided a more fundamental basis for the definition of the ohm. Since 1990 the
1406:
1348:
1410:
1482:
1434:
1442:
847:
Two different methods of establishing a system of electrical units can be chosen. Various artifacts, such as a length of wire or a standard
2408:
1947:
1798:. Thirty-fourth Meeting of the British Association for the Advancement of Science. London: John Murray. p. Foldout facing page 349
947:
697:
184:
proposed a unit derived from existing units of mass, length and time, and of a convenient scale for practical work as early as 1861.
1547:
1684:
Report of the Thirty-First
Meeting of the British Association for the Advancement of Science; held at Manchester in September 1861
2462:
632:
In the US, a double vowel in the prefixed units "kiloohm" and "megaohm" is commonly simplified, producing "kilohm" and "megohm".
1977:
1050:
864:
quantities. However, the centimeter–gram–second, CGS, units turned out to have impractical sizes for practical measurements.
219:
The ohm is defined as an electrical resistance between two points of a conductor when a constant potential difference of one
199:
were redefined in terms of fundamental constants, the ohm is now also defined as an exact value in terms of these constants.
855:
Since so-called "absolute" units of charge and current are expressed as combinations of units of mass, length, and time,
1727:. Thirty-second Meeting of the British Association for the Advancement of Science. London: John Murray. pp. 125–163
1446:
916:
committee, 1864, the resistance unit is referred to as "B.A. unit, or Ohmad". By 1867 the unit is referred to as simply
2124:
888:
experiments to the required precision, so working standards notionally based on the physical definition were required.
2007:
1824:
1753:
1706:
927:
912:
1873:. Thirty-seventh Meeting of the British Association for the Advancement of Science. London: John Murray. p. 488
1392:
IEEE/ASTM SI 10-2002: IEEE/ASTM Standard for Use of the
International System of Units (SI): The Modern Metric System
2314:
1353:
835:) this formula remains valid numerically when these units are used (and thought of as being cancelled or omitted).
800:
2418:
176:. Various empirically derived standard units for electrical resistance were developed in connection with early
59:
1724:
Provisional Report of the
Committee appointed by the British Association on Standards of Electrical Resistance
2133:
1608:
876:
169:
686:
may be calculated from its resistance, and the voltage or current involved. The formula is a combination of
1816:
1745:
1698:
872:
1651:
1722:
1548:"The Ohm Is Where the Art Is: British Telegraph Engineers and the Development of Electrical Standards"
1424:
Thompson, Ambler; Taylor, Barry N. (November 2008) . "Chapter 9.3 Spelling unit names with prefixes".
2457:
1377:
2372:
1868:
1793:
1272:
instead of the Ω symbol, thus, a 10 Ω resistor may be represented as 10R. This is part of the
1682:
2413:
1828:
1757:
1710:
1212:
188:
37:
880:. He proposed a column of pure mercury, of one square millimeter cross section, one meter long:
2117:
2078:
Scanned books of Georg Simon Ohm at the library of the
University of Applied Sciences Nuernberg
2012:
1937:
1840:
1769:
1647:
1343:
896:
668:
867:
Various artifact standards were proposed as the definition of the unit of resistance. In 1860
1337:
1299:, but it is only included for backward compatibility and the Greek uppercase omega character
165:
74:
1951:. Vol. 27 (11th ed.). Cambridge University Press. pp. 738–745, see page 742.
1578:
1932:
1864:
1860:
1848:
1832:
1785:
1777:
1761:
1714:
1643:
1617:
1520:
1254:, this can lead to confusion, making the use of the correct Unicode code point preferable.
1236:
1034:
1010:
A specified copper wire 25 ft (7.620 m) long weighing 345 gr (22.36 g)
892:
881:
856:
691:
656:
636:
22:
1388:
8:
2398:
2034:
1844:
1773:
1511:
1262:
1205:
908:
789:
228:
1621:
1524:
2467:
1820:
1749:
1702:
1570:
1438:
1400:
1296:
950:, at which the ohm was redefined in absolute terms instead of as an artifact standard.
2436:
2322:
2110:
1574:
1243:
1224:
2087:
1903:
1625:
1562:
1528:
2189:
1852:
1836:
1781:
1765:
1718:
1656:
1251:
848:
652:
1498:
1002:
100 million ft/s (30,480 km/s), considered obsolete even in 1884
2342:
2274:
1599:
868:
648:
576:
1390:
1235:
The symbol Ω was suggested, because of the similar sound of ohm and omega, by
2451:
2403:
2327:
2264:
2254:
1942:
1629:
1425:
871:(1816–1892) published a suggestion for a reproducible resistance standard in
2347:
2304:
2289:
2244:
2224:
2141:
2097:
1891:
1856:
1789:
687:
596:
592:
124:
2219:
2174:
1389:
SASB/SCC14 – SCC14 – Quantities, Units, and Letter Symbols (2002-12-30).
1358:
1097:-inch-diameter (1.588 mm) pure annealed copper wire at 15.5 °C
629:, which exhibits a strong dependence of its resistance with temperature.
223:(V), applied to these points, produces in the conductor a current of one
207:
2082:
1265:
standard recommends using the unit name "ohm" as a symbol instead of Ω.
1242:
Historically, some document editing software applications have used the
660:
626:
212:
177:
1936:
1532:
1433:(2nd corrected printing, 2008 ed.). Gaithersburg, Maryland, USA:
2284:
2199:
2092:
1908:
1201:
885:
173:
92:
1603:
2164:
1566:
1317:
1273:
1220:
793:
683:
622:
608:
196:
132:
2041:. 1998. Section 24.1 "Introduction to character entity references"
2352:
2337:
2279:
2209:
2204:
2154:
1978:
Historical Studies in International Corporate Business. Teich p34
1815:
1744:
1697:
1279:
1163:
777:
604:
2367:
2269:
2179:
2159:
2149:
1216:
824:
803:, when each of these quantities has its corresponding SI unit (
625:. In other cases resistance varies, such as in the case of the
619:
584:
224:
192:
144:
140:
21:
This article is about the SI derived unit. For other uses, see
1268:
In the electronics industry it is common to use the character
1158:
Electromagnetic absolute unit in centimeter–gram–second units
2382:
2377:
2362:
2239:
2234:
2229:
2214:
2169:
1870:
Report of the Committee on Standards of Electrical Resistance
1795:
Report of the Committee on Standards of Electrical Resistance
1258:
1148:
612:
600:
588:
161:
136:
1185:
Electrostatic absolute unit in centimeter–gram–second units
2357:
2299:
2294:
2102:
1427:
Guide for the Use of the International System of Units (SI)
1247:
1227:, the ohm is now also defined in terms of these constants.
1133:
A German mile (8,238 yd or 7,533 m) of iron wire
816:
804:
580:
220:
2332:
2249:
935:
1502:
64:
1652:"Measurement of Electrical Quantities and Resistance"
1508:
1316:) is preferred. In MS-DOS and Microsoft Windows, the
1074:
Iron wire 1 km long and 4 mm cross section
1045:
100 cm and 1 mm cross section at 0 °C
700:
502:
466:
409:
371:
356:
341:
326:
302:
278:
263:
248:
240:
1061:
Standard coils deposited at Kew Observatory in 1863
677:
1604:"Vorschlag eines reproducirbaren WiderstandsmaaĂźes"
1417:
901:British Association for the Advancement of Science
754:
564:
182:British Association for the Advancement of Science
957:
2449:
1349:International Committee for Weights and Measures
575:in which the following additional units appear:
755:{\displaystyle P=VI={\frac {V^{2}}{R}}=I^{2}R,}
1483:National Institute of Standards and Technology
1435:National Institute of Standards and Technology
1423:
2118:
1320:ALT 234 may produce the Ω symbol. In Mac OS,
796:of "instantaneous" power over that interval.
227:(A), the conductor not being the seat of any
1994:NIST Special Publication Proceedings of SPIE
1990:Stability of Double-Walled Maganin Resistors
1927:
1925:
1405:: CS1 maint: multiple names: authors list (
1340:, used for indicating the value of resistors
2409:Historical definitions of the SI base units
2008:"The B.A. unit for electrical measurements"
1642:
1592:
1191:
667:spelled backwards, symbol is ℧); it is the
2125:
2111:
1409:) CS1 maint: numeric names: authors list (
948:General Conference on Weights and Measures
642:
1922:
1907:
934:unit of ohm for the resistance, based on
215:is the measurement of resistance in ohms.
1892:"The Electrical Congress Of Paris, 1884"
1539:
1471:
1382:
1378:BIPM SI Brochure: Appendix 1, p.46 (pdf)
907:in 1861 appointed a committee including
206:
42:A laboratory one-ohm standard resistor,
18:SI derived unit of electrical resistance
1931:
1598:
1371:
1364:
1200:Artifact standards are still used, but
2450:
2005:
1257:Where the character set is limited to
211:One of the functions of many types of
2106:
1465:are retained and both are pronounced.
899:(1832–1888) presented a paper at the
784:is the current through the resistor.
172:. It is named after German physicist
1687:. September 1861. pp. xxxix–xl.
1545:
663:, historically known as the "mho" (
13:
1968:, Cassel and Company, London, 1884
1295:, distinct from Greek omega among
1143: in (4.233 mm) diameter
1024:Based on the meter and the second
241:
170:International System of Units (SI)
14:
2479:
2071:
2061:The Unicode Standard, Version 4.0
988:considered obsolete even in 1884
928:International Electrical Congress
678:Power as a function of resistance
635:In alternating current circuits,
2432:
2431:
2098:History of the electrical units.
1445:. NIST Special Publication 811.
1354:Orders of magnitude (resistance)
1051:British Association (B.A.) "ohm"
36:
2093:History of the ohm at sizes.com
2052:
2032:E.g. recommended in HTML 4.01:
2026:
1999:
1996:, The Institute, 1988 pp. 63–64
1982:
1971:
1964:Gordon Wigan (trans. and ed.),
1958:
1884:
1863:; Forbes, D.; Hockin, Charles;
1809:
1738:
1691:
1489:from the original on 2021-01-31
1481:. Gaithersburg, Maryland, USA:
1452:from the original on 2021-01-31
1437:, U.S. Department of Commerce.
1039:1860. A column of pure mercury
832:
2463:Units of electrical resistance
2419:System of units of measurement
2006:Preece, William Henry (1867),
1675:
1636:
1462:
958:Historical units of resistance
1:
1609:Annalen der Physik und Chemie
1087:1 mi (1.609 km) of
877:Annalen der Physik und Chemie
202:
160:, the uppercase Greek letter
43:
2132:
2088:NIST Special Publication 811
7:
2016:, vol. 33, p. 397
1331:
1223:were redefined in terms of
1120:-inch-diameter copper wire
1021:Weber's absolute unit Ă— 10
799:Since the ohm belongs to a
10:
2484:
2064:, accessed 11 October 2006
1310:GREEK CAPITAL LETTER OMEGA
979:Absolute foot/second Ă— 10
973:
970:
967:
964:
838:
831:, which are related as in
682:The power dissipated by a
639:is also measured in ohms.
20:
2427:
2391:
2313:
2188:
2140:
2035:"HTML 4.01 Specification"
1966:Electrician's Pocket Book
1230:
926:On 21 September 1881 the
780:across the resistor, and
120:
116:
98:
88:
80:
70:
58:
53:
35:
30:
2373:minute and second of arc
1902:(758): 26–27. May 1884.
1630:10.1002/andp.18601860502
1192:Realization of standards
801:coherent system of units
2414:2019 revision of the SI
1948:Encyclopædia Britannica
1938:"Units, Physical"
1546:Hunt, Bruce J. (1994).
1213:2019 revision of the SI
1066:Digney, Breguet, Swiss
643:Relation to conductance
189:2019 revision of the SI
2013:Philosophical Magazine
1988:R. Dzuiba and others,
1479:"NIST Guide to the SI"
1344:History of measurement
1314:Ω, Ω
1282:encodes the symbol as
756:
566:
216:
1933:Fleming, John Ambrose
1865:Joule, James Prescott
1849:Siemens, Carl Wilhelm
1786:Joule, James Prescott
1778:Siemens, Carl Wilhelm
1338:Electronic color code
1225:fundamental constants
996:using imperial units
982:using imperial units
757:
567:
210:
166:electrical resistance
75:electrical resistance
2315:Other accepted units
2083:Official SI brochure
1845:Maxwell, James Clerk
1774:Maxwell, James Clerk
1365:Notes and references
1237:William Henry Preece
1110:One mile of special
1035:Siemens mercury unit
882:Siemens mercury unit
857:dimensional analysis
698:
657:electric conductance
637:electrical impedance
238:
23:Ohm (disambiguation)
2399:Conversion of units
1648:Bright, Sir Charles
1622:1860AnP...186....1S
1525:2012PhTea..50...77A
1512:The Physics Teacher
1206:quantum Hall effect
1007:Jacobi copper unit
971:Value in B.A. ohms
790:alternating current
772:is the resistance,
229:electromotive force
111:... is equal to ...
54:General information
2192:with special names
1867:(September 1867).
1792:(September 1864).
1721:(September 1862).
1297:letterlike symbols
897:Sir Charles Bright
752:
562:
560:
496:
460:
403:
365:
350:
335:
320:
296:
272:
257:
217:
180:practice, and the
130:
122:
2445:
2444:
2323:astronomical unit
1859:; Foster, G. C.;
1533:10.1119/1.3677278
1250:, the SI unit of
1189:
1188:
833:§ Definition
731:
559:
550:
533:
519:
508:
495:
486:
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333:
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319:
318:
308:
295:
287:
282:
271:
270:
256:
255:
252:
164:) is the unit of
150:
149:
99:Conversions
2475:
2458:SI derived units
2435:
2434:
2127:
2120:
2113:
2104:
2103:
2065:
2056:
2050:
2049:
2047:
2046:
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2023:
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2003:
1997:
1986:
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1962:
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1940:
1929:
1920:
1919:
1917:
1916:
1911:
1909:10.1038/030026a0
1888:
1882:
1881:
1879:
1878:
1853:Stewart, Balfour
1837:Jenkin, Fleeming
1813:
1807:
1806:
1804:
1803:
1782:Stewart, Balfour
1766:Jenkin, Fleeming
1742:
1736:
1735:
1733:
1732:
1719:Jenkin, Fleeming
1695:
1689:
1688:
1679:
1673:
1672:
1670:
1669:
1640:
1634:
1633:
1596:
1590:
1589:
1587:
1586:
1577:. Archived from
1552:
1543:
1537:
1536:
1506:
1500:
1497:
1495:
1494:
1475:
1469:
1467:
1458:
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1432:
1421:
1415:
1414:
1404:
1396:
1386:
1380:
1375:
1315:
1311:
1308:
1305:
1303:
1294:
1291:
1288:
1286:
1182:
1180:
1177:
1174:
1142:
1141:
1137:
1119:
1118:
1114:
1096:
1095:
1091:
962:
961:
895:(1822–1898) and
830:
822:
814:
810:
783:
775:
771:
767:
761:
759:
758:
753:
745:
744:
732:
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717:
674:
571:
569:
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563:
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531:
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451:
448:
445:
440:
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434:
433:
432:
427:
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401:
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395:
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389:
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378:
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366:
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351:
346:
343:
342:
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331:
328:
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294:
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131:
123:
48:
45:
40:
28:
27:
2483:
2482:
2478:
2477:
2476:
2474:
2473:
2472:
2448:
2447:
2446:
2441:
2423:
2404:Metric prefixes
2387:
2309:
2191:
2184:
2136:
2131:
2074:
2069:
2068:
2057:
2053:
2044:
2042:
2033:
2031:
2027:
2019:
2017:
2004:
2000:
1987:
1983:
1976:
1972:
1963:
1959:
1930:
1923:
1914:
1912:
1890:
1889:
1885:
1876:
1874:
1841:Bright, Charles
1833:Matthiessen, A.
1814:
1810:
1801:
1799:
1770:Bright, Charles
1762:Matthiessen, A.
1743:
1739:
1730:
1728:
1715:Matthiessen, A.
1696:
1692:
1681:
1680:
1676:
1667:
1665:
1657:The Electrician
1641:
1637:
1600:Siemens, Werner
1597:
1593:
1584:
1582:
1550:
1544:
1540:
1507:
1503:
1492:
1490:
1477:
1476:
1472:
1455:
1453:
1449:
1430:
1422:
1418:
1398:
1397:
1387:
1383:
1376:
1372:
1367:
1334:
1328:does the same.
1327:
1323:
1313:
1309:
1306:
1301:
1300:
1292:
1289:
1284:
1283:
1244:Symbol typeface
1233:
1215:, in which the
1194:
1178:
1175:
1172:
1170:
1139:
1135:
1134:
1116:
1112:
1111:
1093:
1089:
1088:
993:Thomson's unit
960:
849:electrochemical
841:
828:
820:
812:
808:
781:
773:
769:
765:
740:
736:
722:
718:
716:
699:
696:
695:
680:
672:
653:SI derived unit
645:
552:
547:
546:
541:
535:
530:
529:
528:
521:
516:
515:
510:
505:
504:
501:
488:
483:
482:
477:
472:
471:
465:
452:
447:
446:
441:
436:
435:
428:
423:
422:
417:
412:
411:
408:
396:
391:
390:
384:
379:
374:
373:
370:
355:
340:
325:
310:
305:
304:
301:
289:
284:
283:
277:
262:
247:
239:
236:
235:
205:
191:, in which the
129:
121:
49:
46:
26:
19:
12:
11:
5:
2481:
2471:
2470:
2465:
2460:
2443:
2442:
2440:
2439:
2428:
2425:
2424:
2422:
2421:
2416:
2411:
2406:
2401:
2395:
2393:
2389:
2388:
2386:
2385:
2380:
2375:
2370:
2365:
2360:
2355:
2350:
2345:
2340:
2335:
2330:
2325:
2319:
2317:
2311:
2310:
2308:
2307:
2302:
2297:
2292:
2287:
2282:
2277:
2272:
2267:
2262:
2257:
2252:
2247:
2242:
2237:
2232:
2227:
2222:
2217:
2212:
2210:degree Celsius
2207:
2202:
2196:
2194:
2190:Derived units
2186:
2185:
2183:
2182:
2177:
2172:
2167:
2162:
2157:
2152:
2146:
2144:
2138:
2137:
2130:
2129:
2122:
2115:
2107:
2101:
2100:
2095:
2090:
2085:
2080:
2073:
2072:External links
2070:
2067:
2066:
2058:Excerpts from
2051:
2025:
1998:
1981:
1970:
1957:
1943:Chisholm, Hugh
1921:
1883:
1861:Clark, Latimer
1821:Wheatstone, C.
1817:Williamson, A.
1808:
1750:Wheatstone, C.
1746:Williamson, A.
1737:
1703:Wheatstone, C.
1699:Williamson, A.
1690:
1674:
1650:(1861-11-09).
1644:Clark, Latimer
1635:
1591:
1567:10.1086/368729
1538:
1501:
1470:
1459:. p. 31:
1416:
1381:
1369:
1368:
1366:
1363:
1362:
1361:
1356:
1351:
1346:
1341:
1333:
1330:
1325:
1321:
1232:
1229:
1211:Following the
1193:
1190:
1187:
1186:
1183:
1168:
1166:
1160:
1159:
1156:
1153:
1151:
1145:
1144:
1131:
1128:
1126:
1122:
1121:
1108:
1105:
1103:
1099:
1098:
1085:
1082:
1080:
1076:
1075:
1072:
1069:
1067:
1063:
1062:
1059:
1056:
1053:
1047:
1046:
1043:
1040:
1037:
1031:
1030:
1028:
1025:
1022:
1018:
1017:
1016:Used in 1850s
1014:
1011:
1008:
1004:
1003:
1000:
997:
994:
990:
989:
986:
983:
980:
976:
975:
972:
969:
966:
959:
956:
869:Werner Siemens
840:
837:
768:is the power,
751:
748:
743:
739:
735:
730:
725:
721:
715:
712:
709:
706:
703:
679:
676:
644:
641:
573:
572:
555:
544:
538:
524:
513:
500:
491:
480:
464:
455:
444:
431:
420:
407:
399:
382:
369:
354:
339:
324:
313:
300:
292:
276:
267:
261:
246:
243:
204:
201:
187:Following the
148:
147:
127:
118:
117:
114:
113:
108:
101:
100:
96:
95:
90:
86:
85:
82:
78:
77:
72:
68:
67:
62:
56:
55:
51:
50:
41:
33:
32:
17:
9:
6:
4:
3:
2:
2480:
2469:
2466:
2464:
2461:
2459:
2456:
2455:
2453:
2438:
2430:
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2420:
2417:
2415:
2412:
2410:
2407:
2405:
2402:
2400:
2397:
2396:
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2390:
2384:
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2379:
2376:
2374:
2371:
2369:
2366:
2364:
2361:
2359:
2356:
2354:
2351:
2349:
2346:
2344:
2343:degree of arc
2341:
2339:
2336:
2334:
2331:
2329:
2326:
2324:
2321:
2320:
2318:
2316:
2312:
2306:
2303:
2301:
2298:
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2283:
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2278:
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2273:
2271:
2268:
2266:
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2258:
2256:
2253:
2251:
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2246:
2243:
2241:
2238:
2236:
2233:
2231:
2228:
2226:
2223:
2221:
2218:
2216:
2213:
2211:
2208:
2206:
2203:
2201:
2198:
2197:
2195:
2193:
2187:
2181:
2178:
2176:
2173:
2171:
2168:
2166:
2163:
2161:
2158:
2156:
2153:
2151:
2148:
2147:
2145:
2143:
2139:
2135:
2128:
2123:
2121:
2116:
2114:
2109:
2108:
2105:
2099:
2096:
2094:
2091:
2089:
2086:
2084:
2081:
2079:
2076:
2075:
2063:
2062:
2055:
2040:
2036:
2029:
2015:
2014:
2009:
2002:
1995:
1991:
1985:
1979:
1974:
1967:
1961:
1954:
1950:
1949:
1944:
1939:
1934:
1928:
1926:
1910:
1905:
1901:
1897:
1893:
1887:
1872:
1871:
1866:
1862:
1858:
1857:Varley, C. F.
1854:
1850:
1846:
1842:
1838:
1834:
1830:
1829:Miller, W. H.
1826:
1822:
1818:
1812:
1797:
1796:
1791:
1790:Varley, C. F.
1787:
1783:
1779:
1775:
1771:
1767:
1763:
1759:
1758:Miller, W. H.
1755:
1751:
1747:
1741:
1726:
1725:
1720:
1716:
1712:
1711:Miller, W. H.
1708:
1704:
1700:
1694:
1686:
1685:
1678:
1663:
1659:
1658:
1653:
1649:
1645:
1639:
1631:
1627:
1623:
1619:
1615:
1612:(in German).
1611:
1610:
1605:
1601:
1595:
1581:on 2014-03-08
1580:
1576:
1572:
1568:
1564:
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1505:
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1484:
1480:
1474:
1466:
1463:
1448:
1444:
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1436:
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1408:
1402:
1394:
1393:
1385:
1379:
1374:
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1350:
1347:
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1339:
1336:
1335:
1329:
1319:
1298:
1281:
1277:
1275:
1271:
1266:
1264:
1260:
1255:
1253:
1249:
1245:
1240:
1238:
1228:
1226:
1222:
1218:
1214:
1209:
1207:
1203:
1198:
1184:
1169:
1167:
1165:
1162:
1161:
1157:
1154:
1152:
1150:
1147:
1146:
1132:
1129:
1127:
1124:
1123:
1109:
1106:
1104:
1101:
1100:
1086:
1083:
1081:
1078:
1077:
1073:
1071:9.266–10.420
1070:
1068:
1065:
1064:
1060:
1057:
1054:
1052:
1049:
1048:
1044:
1041:
1038:
1036:
1033:
1032:
1029:
1026:
1023:
1020:
1019:
1015:
1012:
1009:
1006:
1005:
1001:
998:
995:
992:
991:
987:
984:
981:
978:
977:
963:
955:
951:
949:
944:
939:
937:
933:
929:
924:
921:
919:
914:
910:
906:
902:
898:
894:
893:Latimer Clark
889:
887:
883:
879:
878:
874:
873:Poggendorff's
870:
865:
861:
858:
853:
850:
845:
836:
834:
826:
818:
806:
802:
797:
795:
791:
785:
779:
762:
749:
746:
741:
737:
733:
728:
723:
719:
713:
710:
707:
704:
701:
693:
689:
685:
675:
670:
666:
662:
658:
654:
650:
640:
638:
633:
630:
628:
624:
621:
616:
614:
610:
606:
602:
598:
594:
590:
586:
582:
578:
553:
542:
536:
522:
511:
498:
489:
478:
462:
453:
442:
429:
418:
405:
397:
380:
367:
352:
337:
322:
311:
298:
290:
274:
265:
259:
244:
234:
233:
232:
230:
226:
222:
214:
209:
200:
198:
194:
190:
185:
183:
179:
175:
171:
167:
163:
159:
155:
146:
142:
138:
134:
128:
126:
125:SI base units
119:
115:
112:
109:
107:
103:
102:
97:
94:
91:
87:
83:
79:
76:
73:
69:
66:
63:
61:
57:
52:
39:
34:
29:
24:
16:
2348:electronvolt
2259:
2059:
2054:
2043:. Retrieved
2038:
2028:
2018:, retrieved
2011:
2001:
1993:
1989:
1984:
1973:
1965:
1960:
1952:
1946:
1913:. Retrieved
1899:
1895:
1886:
1875:. Retrieved
1869:
1811:
1800:. Retrieved
1794:
1740:
1729:. Retrieved
1723:
1693:
1683:
1677:
1666:. Retrieved
1661:
1655:
1638:
1613:
1607:
1594:
1583:. Retrieved
1579:the original
1558:
1554:
1541:
1519:(2): 77–79.
1516:
1510:
1504:
1491:. Retrieved
1473:
1460:
1454:. Retrieved
1426:
1419:
1391:
1384:
1373:
1278:
1269:
1267:
1256:
1241:
1234:
1210:
1199:
1195:
1125:German mile
1079:Matthiessen
952:
942:
940:
931:
925:
922:
917:
890:
875:
866:
862:
854:
846:
842:
798:
786:
763:
681:
671:of the ohm:
664:
646:
634:
631:
617:
574:
218:
186:
157:
153:
151:
110:
105:
71:Unit of
15:
1825:Thomson, W.
1754:Thomson, W.
1707:Thomson, W.
1616:(5): 1–20.
1359:Resistivity
968:Definition
794:integration
692:Joule's law
651:(S) is the
213:multimeters
89:Named after
60:Unit system
47: 1917
2452:Categories
2142:Base units
2045:2018-11-22
2020:2017-02-26
1915:2023-12-23
1877:2014-02-27
1802:2014-02-27
1731:2014-02-27
1668:2014-02-27
1585:2014-02-27
1493:2021-01-31
1468:(85 pages)
1461:Reference
1456:2021-01-31
1263:IEEE 260.1
930:defined a
811:, ohm for
673:1 S = 1 Ω.
669:reciprocal
661:admittance
627:thermistor
611:(kg), and
203:Definition
178:telegraphy
2468:Georg Ohm
2285:steradian
2200:becquerel
1575:145557228
1561:: 48–63.
1401:cite book
1202:metrology
932:practical
891:In 1861,
886:metrology
688:Ohm's law
623:resistors
543:⋅
512:⋅
479:⋅
443:⋅
419:⋅
381:⋅
242:Ω
174:Georg Ohm
156:(symbol:
104:1 Ω
93:Georg Ohm
2437:Category
2392:See also
2165:kilogram
2134:SI units
1935:(1911).
1664:(1): 3–4
1602:(1860).
1487:Archived
1447:Archived
1332:See also
1318:alt code
1293:OHM SIGN
1290:Ω
1274:RKM code
1221:kilogram
1219:and the
974:Remarks
684:resistor
609:kilogram
197:kilogram
195:and the
2353:hectare
2338:decibel
2280:sievert
2275:siemens
2205:coulomb
2155:candela
1945:(ed.).
1618:Bibcode
1521:Bibcode
1307:Ω
1280:Unicode
1164:Statohm
1138:⁄
1115:⁄
1102:Varley
1092:⁄
1042:0.9537
1027:0.9191
1013:0.6367
999:0.3202
985:0.3048
913:Thomson
909:Maxwell
839:History
778:voltage
776:is the
649:siemens
605:coulomb
577:siemens
168:in the
2368:minute
2328:dalton
2270:radian
2265:pascal
2255:newton
2180:second
2160:kelvin
2150:ampere
1896:Nature
1573:
1555:Osiris
1443:NSPUE3
1441:
1304:
1302:U+03A9
1287:
1285:U+2126
1261:, the
1231:Symbol
1217:ampere
1130:57.44
1107:25.61
1084:13.59
1058:1.000
825:ampere
764:where
620:linear
599:(Wb),
585:second
225:ampere
193:ampere
106:in ...
81:Symbol
2383:tonne
2378:neper
2363:litre
2305:weber
2290:tesla
2245:lumen
2240:katal
2235:joule
2230:hertz
2225:henry
2215:farad
2170:metre
1941:. In
1571:S2CID
1557:. 2.
1551:(PDF)
1450:(PDF)
1439:CODEN
1431:(PDF)
1322:⌥ Opt
1259:ASCII
1252:power
1171:8.987
1149:Abohm
1055:1863
965:Unit
943:legal
615:(m).
613:meter
607:(C),
603:(J),
601:joule
597:weber
595:(H),
593:henry
591:(F),
589:farad
587:(s),
583:(W),
579:(S),
162:omega
2358:hour
2300:watt
2295:volt
2220:gray
2175:mole
1411:link
1407:link
1248:watt
911:and
905:BAAS
827:for
823:and
819:for
817:volt
807:for
805:watt
690:and
659:and
647:The
581:watt
221:volt
152:The
2333:day
2260:ohm
2250:lux
2039:W3C
1992:in
1904:doi
1626:doi
1614:186
1563:doi
1529:doi
1176:787
1173:551
1155:10
936:CGS
918:ohm
665:ohm
655:of
154:ohm
31:ohm
2454::
2037:.
2010:,
1924:^
1900:30
1898:.
1894:.
1855:;
1851:;
1847:;
1843:;
1839:;
1835:;
1831:;
1827:;
1823:;
1819:;
1788:;
1784:;
1780:;
1776:;
1772:;
1768:;
1764:;
1760:;
1756:;
1752:;
1748:;
1717:;
1713:;
1709:;
1705:;
1701:;
1660:.
1654:.
1646:;
1624:.
1606:.
1569:.
1553:.
1527:.
1517:50
1515:.
1403:}}
1399:{{
1181:10
1117:16
1094:16
941:A
920:.
815:,
694::
507:kg
414:kg
359:Wb
231:.
133:kg
65:SI
44:c.
2126:e
2119:t
2112:v
2048:.
1918:.
1906::
1880:.
1805:.
1734:.
1671:.
1662:1
1632:.
1628::
1620::
1588:.
1565::
1559:9
1535:.
1531::
1523::
1496:.
1413:)
1395:.
1326:Z
1324:+
1312:(
1270:R
1179:Ă—
1140:6
1136:1
1113:1
1090:1
829:I
821:V
813:R
809:P
782:I
774:V
770:R
766:P
750:,
747:R
742:2
738:I
734:=
729:R
724:2
720:V
714:=
711:I
708:V
705:=
702:P
554:2
549:A
537:3
532:s
523:2
518:m
499:=
490:2
485:A
474:s
469:J
463:=
454:2
449:C
438:s
430:2
425:m
406:=
398:2
393:C
386:s
376:J
368:=
362:C
353:=
347:s
344:H
338:=
332:F
329:s
323:=
317:W
312:2
307:V
299:=
291:2
286:A
281:W
275:=
269:S
266:1
260:=
254:A
251:V
245:=
158:Ω
145:A
143:â‹…
141:s
139:â‹…
137:m
135:â‹…
84:Ω
25:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
