957:
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
581:
248:
576:{\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}}}}
49:
863:
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.
855:
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.
219:
2444:
956:
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
1475:
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
1207:
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
874:
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
862:
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
926:
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
854:
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
1287:. 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.
870:
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.
964:
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.
895:. 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
798:
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
1208:
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.
1497:
1219:
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.
803:
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
771:
1496:(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.
934:
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.
1257:
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
2088:
914:
meeting suggesting that standards for electrical units be established and suggesting names for these units derived from eminent philosophers, 'Ohma', 'Farad' and 'Volt'. The
915:
911:
192:
1417:
1359:
1421:
1520:
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".
1493:
1445:
1250:
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.
629:
In many cases the resistance of a conductor is approximately constant within a certain range of voltages, temperatures, and other parameters. These are called
949:
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.
2071:
2419:
1964:
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
1958:
1489:
958:
1215:
experiments relating accurately dimensioned inductors and capacitors provided a more fundamental basis for the definition of the ohm. Since 1990 the
2473:
1453:
858:
Two different methods of establishing a system of electrical units can be chosen. Various artifacts, such as a length of wire or a standard
1809:. Thirty-fourth Meeting of the British Association for the Advancement of Science. London: John Murray. p. Foldout facing page 349
2135:
708:
195:
proposed a unit derived from existing units of mass, length and time, and of a convenient scale for practical work as early as 1861.
1835:
1764:
1717:
1558:
938:
923:
1695:
Report of the Thirty-First
Meeting of the British Association for the Advancement of Science; held at Manchester in September 1861
2325:
1364:
811:
643:
In the US, a double vowel in the prefixed units "kiloohm" and "megaohm" is commonly simplified, producing "kilohm" and "megohm".
1988:
2429:
875:
quantities. However, the centimeter–gram–second, CGS, units turned out to have impractical sizes for practical measurements.
230:
The ohm is defined as an electrical resistance between two points of a conductor when a constant potential difference of one
210:
were redefined in terms of fundamental constants, the ohm is now also defined as an exact value in terms of these constants.
70:
2144:
1619:
887:
180:
866:
Since so-called "absolute" units of charge and current are expressed as combinations of units of mass, length, and time,
1827:
1756:
1738:. Thirty-second Meeting of the British Association for the Advancement of Science. London: John Murray. pp. 125–163
1709:
1457:
927:
committee, 1864, the resistance unit is referred to as "B.A. unit, or Ohmad". By 1867 the unit is referred to as simply
883:
899:
experiments to the required precision, so working standards notionally based on the physical definition were required.
48:
2018:
1061:
1884:. Thirty-seventh Meeting of the British Association for the Advancement of Science. London: John Murray. p. 488
1403:
IEEE/ASTM SI 10-2002: IEEE/ASTM Standard for Use of the
International System of Units (SI): The Modern Metric System
846:) this formula remains valid numerically when these units are used (and thought of as being cancelled or omitted).
2468:
2383:
187:. Various empirically derived standard units for electrical resistance were developed in connection with early
1735:
Provisional Report of the
Committee appointed by the British Association on Standards of Electrical Resistance
2424:
1839:
1768:
1721:
1223:
697:
may be calculated from its resistance, and the voltage or current involved. The formula is a combination of
199:
2128:
2023:
1851:
1780:
1658:
1354:
907:
679:
1348:
176:
85:
1662:
1733:
1559:"The Ohm Is Where the Art Is: British Telegraph Engineers and the Development of Electrical Standards"
1435:
Thompson, Ambler; Taylor, Barry N. (November 2008) . "Chapter 9.3 Spelling unit names with prefixes".
1943:
1875:
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1859:
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647:
33:
2409:
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1855:
1804:
1784:
1522:
1283:
instead of the Ω symbol, thus, a 10 Ω resistor may be represented as 10R. This is part of the
1273:
1216:
919:
800:
239:
1693:
2478:
1831:
1760:
1713:
1581:
1449:
1411:
1307:
891:. He proposed a column of pure mercury, of one square millimeter cross section, one meter long:
2089:
Scanned books of Georg Simon Ohm at the library of the
University of Applied Sciences Nuernberg
1948:
2447:
2333:
2121:
1254:
1235:
878:
Various artifact standards were proposed as the definition of the unit of resistance. In 1860
1310:, but it is only included for backward compatibility and the Greek uppercase omega character
1962:. Vol. 27 (11th ed.). Cambridge University Press. pp. 738–745, see page 742.
1914:
1636:
1589:
1573:
1539:
1265:, this can lead to confusion, making the use of the correct Unicode code point preferable.
1021:
A specified copper wire 25 ft (7.620 m) long weighing 345 gr (22.36 g)
2200:
1863:
1847:
1792:
1776:
1729:
1667:
1262:
859:
663:
2045:
1632:
1535:
2353:
2285:
1610:
961:, at which the ohm was redefined in absolute terms instead of as an artifact standard.
879:
659:
587:
218:
2462:
2414:
2338:
2275:
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1953:
1585:
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2098:
1867:
1800:
607:
603:
135:
698:
2230:
2185:
1509:
1369:
1013:
100 million ft/s (30,480 km/s), considered obsolete even in 1884
1401:
1246:
The symbol Ω was suggested, because of the similar sound of ohm and omega, by
671:
637:
223:
188:
1640:
1436:
882:(1816–1892) published a suggestion for a reproducible resistance standard in
2295:
2210:
1212:
896:
184:
103:
2108:
1902:
2175:
1400:
SASB/SCC14 – SCC14 – Quantities, Units, and Letter Symbols (2002-12-30).
1328:
1284:
1231:
1108:-inch-diameter (1.588 mm) pure annealed copper wire at 15.5 °C
804:
694:
640:, which exhibits a strong dependence of its resistance with temperature.
633:
619:
234:(V), applied to these points, produces in the conductor a current of one
207:
143:
2093:
1276:
standard recommends using the unit name "ohm" as a symbol instead of Ω.
1253:
Historically, some document editing software applications have used the
2363:
2348:
2290:
2220:
2215:
2165:
1290:
1174:
788:
615:
1947:
1543:
1444:(2nd corrected printing, 2008 ed.). Gaithersburg, Maryland, USA:
17:
2378:
2280:
2190:
2170:
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2103:
1919:
1227:
835:
630:
595:
235:
203:
155:
151:
1614:
1577:
2393:
2388:
2373:
2250:
2245:
2240:
2225:
2180:
2052:. 1998. Section 24.1 "Introduction to character entity references"
1269:
1159:
623:
611:
599:
217:
172:
147:
1989:
Historical Studies in International Corporate Business. Teich p34
2368:
2310:
2305:
1258:
827:
815:
591:
231:
2117:
814:, when each of these quantities has its corresponding SI unit (
636:. In other cases resistance varies, such as in the case of the
32:
This article is about the SI derived unit. For other uses, see
2343:
2260:
1279:
In the electronics industry it is common to use the character
1169:
Electromagnetic absolute unit in centimeter–gram–second units
946:
1881:
Report of the Committee on Standards of Electrical Resistance
1806:
Report of the Committee on Standards of Electrical Resistance
1196:
Electrostatic absolute unit in centimeter–gram–second units
2113:
1438:
Guide for the Use of the International System of Units (SI)
1238:, the ohm is now also defined in terms of these constants.
1144:
A German mile (8,238 yd or 7,533 m) of iron wire
75:
1663:"Measurement of Electrical Quantities and Resistance"
1327:) is preferred. In MS-DOS and Microsoft Windows, the
1085:
Iron wire 1 km long and 4 mm cross section
1056:
100 cm and 1 mm cross section at 0 °C
711:
513:
477:
420:
382:
367:
352:
337:
313:
289:
274:
259:
251:
1072:
Standard coils deposited at Kew Observatory in 1863
2402:
2324:
2199:
2151:
1615:"Vorschlag eines reproducirbaren WiderstandsmaaĂźes"
131:
109:
99:
91:
81:
69:
64:
41:
912:British Association for the Advancement of Science
765:
575:
193:British Association for the Advancement of Science
1360:International Committee for Weights and Measures
586:in which the following additional units appear:
766:{\displaystyle P=VI={\frac {V^{2}}{R}}=I^{2}R,}
1494:National Institute of Standards and Technology
1446:National Institute of Standards and Technology
2129:
1331:ALT 234 may produce the Ω symbol. In Mac OS,
807:of "instantaneous" power over that interval.
238:(A), the conductor not being the seat of any
8:
2005:NIST Special Publication Proceedings of SPIE
2001:Stability of Double-Walled Maganin Resistors
1938:
1936:
1416:: CS1 maint: multiple names: authors list (
1351:, used for indicating the value of resistors
2420:Historical definitions of the SI base units
2019:"The B.A. unit for electrical measurements"
678:spelled backwards, symbol is ℧); it is the
2136:
2122:
2114:
1420:) CS1 maint: numeric names: authors list (
959:General Conference on Weights and Measures
38:
1918:
945:unit of ohm for the resistance, based on
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733:
727:
710:
563:
558:
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541:
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366:
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336:
321:
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273:
258:
250:
226:is the measurement of resistance in ohms.
1903:"The Electrical Congress Of Paris, 1884"
1389:BIPM SI Brochure: Appendix 1, p.46 (pdf)
1336:
1332:
972:
918:in 1861 appointed a committee including
53:A laboratory one-ohm standard resistor,
29:SI derived unit of electrical resistance
1381:
1211:Artifact standards are still used, but
1409:
1268:Where the character set is limited to
222:One of the functions of many types of
1476:are retained and both are pronounced.
910:(1832–1888) presented a paper at the
795:is the current through the resistor.
183:. It is named after German physicist
7:
1698:. September 1861. pp. xxxix–xl.
674:, historically known as the "mho" (
1979:, Cassel and Company, London, 1884
1306:, distinct from Greek omega among
1154: in (4.233 mm) diameter
1035:Based on the meter and the second
252:
181:International System of Units (SI)
25:
2072:The Unicode Standard, Version 4.0
999:considered obsolete even in 1884
939:International Electrical Congress
689:Power as a function of resistance
646:In alternating current circuits,
113:
2443:
2442:
2109:History of the electrical units.
1456:. NIST Special Publication 811.
1365:Orders of magnitude (resistance)
1062:British Association (B.A.) "ohm"
47:
2104:History of the ohm at sizes.com
2043:E.g. recommended in HTML 4.01:
2007:, The Institute, 1988 pp. 63–64
1975:Gordon Wigan (trans. and ed.),
1874:; Forbes, D.; Hockin, Charles;
1500:from the original on 2021-01-31
1492:. Gaithersburg, Maryland, USA:
1463:from the original on 2021-01-31
1448:, U.S. Department of Commerce.
1050:1860. A column of pure mercury
843:
2474:Units of electrical resistance
2430:System of units of measurement
2017:Preece, William Henry (1867),
1473:
969:Historical units of resistance
1:
1620:Annalen der Physik und Chemie
1098:1 mi (1.609 km) of
888:Annalen der Physik und Chemie
171:, the uppercase Greek letter
54:
2099:NIST Special Publication 811
2027:, vol. 33, p. 397
1234:were redefined in terms of
1131:-inch-diameter copper wire
1032:Weber's absolute unit Ă— 10
810:Since the ohm belongs to a
2495:
2075:, accessed 11 October 2006
1321:GREEK CAPITAL LETTER OMEGA
990:Absolute foot/second Ă— 10
984:
981:
978:
975:
842:, which are related as in
693:The power dissipated by a
650:is also measured in ohms.
31:
2438:
2046:"HTML 4.01 Specification"
1977:Electrician's Pocket Book
937:On 21 September 1881 the
791:across the resistor, and
127:
46:
2384:minute and second of arc
1913:(758): 26–27. May 1884.
1641:10.1002/andp.18601860502
1203:Realization of standards
812:coherent system of units
2425:2019 revision of the SI
1959:Encyclopædia Britannica
1949:"Units, Physical"
1557:Hunt, Bruce J. (1994).
1224:2019 revision of the SI
1077:Digney, Breguet, Swiss
654:Relation to conductance
200:2019 revision of the SI
2024:Philosophical Magazine
1999:R. Dzuiba and others,
1490:"NIST Guide to the SI"
1355:History of measurement
1325:Ω, Ω
1293:encodes the symbol as
767:
577:
227:
1944:Fleming, John Ambrose
1876:Joule, James Prescott
1860:Siemens, Carl Wilhelm
1797:Joule, James Prescott
1789:Siemens, Carl Wilhelm
1349:Electronic color code
1236:fundamental constants
1007:using imperial units
993:using imperial units
768:
578:
221:
177:electrical resistance
86:electrical resistance
2326:Other accepted units
2094:Official SI brochure
1856:Maxwell, James Clerk
1785:Maxwell, James Clerk
1376:Notes and references
1248:William Henry Preece
1121:One mile of special
1046:Siemens mercury unit
893:Siemens mercury unit
868:dimensional analysis
709:
668:electric conductance
648:electrical impedance
249:
34:Ohm (disambiguation)
2410:Conversion of units
1659:Bright, Sir Charles
1633:1860AnP...186....1S
1536:2012PhTea..50...77A
1523:The Physics Teacher
1217:quantum Hall effect
1018:Jacobi copper unit
982:Value in B.A. ohms
801:alternating current
783:is the resistance,
240:electromotive force
122:... is equal to ...
65:General information
2203:with special names
1878:(September 1867).
1803:(September 1864).
1732:(September 1862).
1308:letterlike symbols
908:Sir Charles Bright
763:
573:
571:
507:
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361:
346:
331:
307:
283:
268:
228:
191:practice, and the
141:
133:
2456:
2455:
2334:astronomical unit
1870:; Foster, G. C.;
1544:10.1119/1.3677278
1261:, the SI unit of
1200:
1199:
844:§ Definition
742:
570:
561:
544:
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282:
281:
267:
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175:) is the unit of
161:
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110:Conversions
16:(Redirected from
2486:
2469:SI derived units
2446:
2445:
2138:
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1920:10.1038/030026a0
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1864:Stewart, Balfour
1848:Jenkin, Fleeming
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1818:
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1815:
1814:
1793:Stewart, Balfour
1777:Jenkin, Fleeming
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1730:Jenkin, Fleeming
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1607:
1601:
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1598:
1597:
1588:. Archived from
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906:(1822–1898) and
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2415:Metric prefixes
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2320:
2202:
2195:
2147:
2142:
2085:
2080:
2079:
2068:
2064:
2055:
2053:
2044:
2042:
2038:
2030:
2028:
2016:
2015:
2011:
1998:
1994:
1987:
1983:
1974:
1970:
1942:
1941:
1934:
1925:
1923:
1901:
1900:
1896:
1887:
1885:
1852:Bright, Charles
1844:Matthiessen, A.
1826:
1825:
1821:
1812:
1810:
1781:Bright, Charles
1773:Matthiessen, A.
1755:
1754:
1750:
1741:
1739:
1726:Matthiessen, A.
1708:
1707:
1703:
1692:
1691:
1687:
1678:
1676:
1668:The Electrician
1653:
1652:
1648:
1611:Siemens, Werner
1609:
1608:
1604:
1595:
1593:
1561:
1556:
1555:
1551:
1519:
1518:
1514:
1503:
1501:
1488:
1487:
1483:
1466:
1464:
1460:
1441:
1434:
1433:
1429:
1408:
1399:
1398:
1394:
1387:
1383:
1378:
1345:
1339:does the same.
1338:
1334:
1324:
1320:
1317:
1312:
1311:
1303:
1300:
1295:
1294:
1255:Symbol typeface
1244:
1226:, in which the
1205:
1189:
1186:
1183:
1181:
1150:
1146:
1145:
1127:
1123:
1122:
1104:
1100:
1099:
1004:Thomson's unit
971:
860:electrochemical
852:
839:
831:
823:
819:
792:
784:
780:
776:
747:
729:
707:
706:
691:
683:
664:SI derived unit
656:
557:
540:
539:
526:
515:
493:
482:
457:
446:
433:
422:
401:
384:
315:
294:
247:
246:
216:
202:, in which the
140:
132:
60:
57:
37:
30:
23:
22:
15:
12:
11:
5:
2492:
2490:
2482:
2481:
2476:
2471:
2461:
2460:
2454:
2453:
2451:
2450:
2439:
2436:
2435:
2433:
2432:
2427:
2422:
2417:
2412:
2406:
2404:
2400:
2399:
2397:
2396:
2391:
2386:
2381:
2376:
2371:
2366:
2361:
2356:
2351:
2346:
2341:
2336:
2330:
2328:
2322:
2321:
2319:
2318:
2313:
2308:
2303:
2298:
2293:
2288:
2283:
2278:
2273:
2268:
2263:
2258:
2253:
2248:
2243:
2238:
2233:
2228:
2223:
2221:degree Celsius
2218:
2213:
2207:
2205:
2201:Derived units
2197:
2196:
2194:
2193:
2188:
2183:
2178:
2173:
2168:
2163:
2157:
2155:
2149:
2148:
2143:
2141:
2140:
2133:
2126:
2118:
2112:
2111:
2106:
2101:
2096:
2091:
2084:
2083:External links
2081:
2078:
2077:
2069:Excerpts from
2062:
2036:
2009:
1992:
1981:
1968:
1954:Chisholm, Hugh
1932:
1894:
1872:Clark, Latimer
1832:Wheatstone, C.
1828:Williamson, A.
1819:
1761:Wheatstone, C.
1757:Williamson, A.
1748:
1714:Wheatstone, C.
1710:Williamson, A.
1701:
1685:
1661:(1861-11-09).
1655:Clark, Latimer
1646:
1602:
1578:10.1086/368729
1549:
1512:
1481:
1470:. p. 31:
1427:
1392:
1380:
1379:
1377:
1374:
1373:
1372:
1367:
1362:
1357:
1352:
1344:
1341:
1243:
1240:
1222:Following the
1204:
1201:
1198:
1197:
1194:
1179:
1177:
1171:
1170:
1167:
1164:
1162:
1156:
1155:
1142:
1139:
1137:
1133:
1132:
1119:
1116:
1114:
1110:
1109:
1096:
1093:
1091:
1087:
1086:
1083:
1080:
1078:
1074:
1073:
1070:
1067:
1064:
1058:
1057:
1054:
1051:
1048:
1042:
1041:
1039:
1036:
1033:
1029:
1028:
1027:Used in 1850s
1025:
1022:
1019:
1015:
1014:
1011:
1008:
1005:
1001:
1000:
997:
994:
991:
987:
986:
983:
980:
977:
970:
967:
880:Werner Siemens
851:
848:
779:is the power,
762:
759:
754:
750:
746:
741:
736:
732:
726:
723:
720:
717:
714:
690:
687:
655:
652:
584:
583:
566:
555:
549:
535:
524:
511:
502:
491:
475:
466:
455:
442:
431:
418:
410:
393:
380:
365:
350:
335:
324:
311:
303:
287:
278:
272:
257:
254:
215:
212:
198:Following the
159:
158:
138:
129:
128:
125:
124:
119:
112:
111:
107:
106:
101:
97:
96:
93:
89:
88:
83:
79:
78:
73:
67:
66:
62:
61:
52:
44:
43:
28:
24:
14:
13:
10:
9:
6:
4:
3:
2:
2491:
2480:
2477:
2475:
2472:
2470:
2467:
2466:
2464:
2449:
2441:
2440:
2437:
2431:
2428:
2426:
2423:
2421:
2418:
2416:
2413:
2411:
2408:
2407:
2405:
2401:
2395:
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2387:
2385:
2382:
2380:
2377:
2375:
2372:
2370:
2367:
2365:
2362:
2360:
2357:
2355:
2354:degree of arc
2352:
2350:
2347:
2345:
2342:
2340:
2337:
2335:
2332:
2331:
2329:
2327:
2323:
2317:
2314:
2312:
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2307:
2304:
2302:
2299:
2297:
2294:
2292:
2289:
2287:
2284:
2282:
2279:
2277:
2274:
2272:
2269:
2267:
2264:
2262:
2259:
2257:
2254:
2252:
2249:
2247:
2244:
2242:
2239:
2237:
2234:
2232:
2229:
2227:
2224:
2222:
2219:
2217:
2214:
2212:
2209:
2208:
2206:
2204:
2198:
2192:
2189:
2187:
2184:
2182:
2179:
2177:
2174:
2172:
2169:
2167:
2164:
2162:
2159:
2158:
2156:
2154:
2150:
2146:
2139:
2134:
2132:
2127:
2125:
2120:
2119:
2116:
2110:
2107:
2105:
2102:
2100:
2097:
2095:
2092:
2090:
2087:
2086:
2082:
2074:
2073:
2066:
2063:
2051:
2047:
2040:
2037:
2026:
2025:
2020:
2013:
2010:
2006:
2002:
1996:
1993:
1990:
1985:
1982:
1978:
1972:
1969:
1965:
1961:
1960:
1955:
1950:
1945:
1939:
1937:
1933:
1921:
1916:
1912:
1908:
1904:
1898:
1895:
1883:
1882:
1877:
1873:
1869:
1868:Varley, C. F.
1865:
1861:
1857:
1853:
1849:
1845:
1841:
1840:Miller, W. H.
1837:
1833:
1829:
1823:
1820:
1808:
1807:
1802:
1801:Varley, C. F.
1798:
1794:
1790:
1786:
1782:
1778:
1774:
1770:
1769:Miller, W. H.
1766:
1762:
1758:
1752:
1749:
1737:
1736:
1731:
1727:
1723:
1722:Miller, W. H.
1719:
1715:
1711:
1705:
1702:
1697:
1696:
1689:
1686:
1674:
1670:
1669:
1664:
1660:
1656:
1650:
1647:
1642:
1638:
1634:
1630:
1626:
1623:(in German).
1622:
1621:
1616:
1612:
1606:
1603:
1592:on 2014-03-08
1591:
1587:
1583:
1579:
1575:
1571:
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1560:
1553:
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1533:
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1513:
1510:
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1474:
1459:
1455:
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1440:
1439:
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1428:
1423:
1419:
1413:
1405:
1404:
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1390:
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1375:
1371:
1368:
1366:
1363:
1361:
1358:
1356:
1353:
1350:
1347:
1346:
1342:
1340:
1330:
1309:
1292:
1288:
1286:
1282:
1277:
1275:
1271:
1266:
1264:
1260:
1256:
1251:
1249:
1241:
1239:
1237:
1233:
1229:
1225:
1220:
1218:
1214:
1209:
1202:
1195:
1180:
1178:
1176:
1173:
1172:
1168:
1165:
1163:
1161:
1158:
1157:
1143:
1140:
1138:
1135:
1134:
1120:
1117:
1115:
1112:
1111:
1097:
1094:
1092:
1089:
1088:
1084:
1082:9.266–10.420
1081:
1079:
1076:
1075:
1071:
1068:
1065:
1063:
1060:
1059:
1055:
1052:
1049:
1047:
1044:
1043:
1040:
1037:
1034:
1031:
1030:
1026:
1023:
1020:
1017:
1016:
1012:
1009:
1006:
1003:
1002:
998:
995:
992:
989:
988:
974:
968:
966:
962:
960:
955:
950:
948:
944:
940:
935:
932:
930:
925:
921:
917:
913:
909:
905:
904:Latimer Clark
900:
898:
894:
890:
889:
885:
884:Poggendorff's
881:
876:
872:
869:
864:
861:
856:
849:
847:
845:
837:
829:
817:
813:
808:
806:
802:
796:
790:
773:
760:
757:
752:
748:
744:
739:
734:
730:
724:
721:
718:
715:
712:
704:
700:
696:
688:
686:
681:
677:
673:
669:
665:
661:
653:
651:
649:
644:
641:
639:
635:
632:
627:
625:
621:
617:
613:
609:
605:
601:
597:
593:
589:
564:
553:
547:
533:
522:
509:
500:
489:
473:
464:
453:
440:
429:
416:
408:
391:
378:
363:
348:
333:
322:
309:
301:
285:
276:
270:
255:
245:
244:
243:
241:
237:
233:
225:
220:
213:
211:
209:
205:
201:
196:
194:
190:
186:
182:
178:
174:
170:
166:
157:
153:
149:
145:
139:
137:
136:SI base units
130:
126:
123:
120:
118:
114:
108:
105:
102:
98:
94:
90:
87:
84:
80:
77:
74:
72:
68:
63:
50:
45:
40:
35:
27:
19:
2359:electronvolt
2270:
2070:
2065:
2054:. Retrieved
2049:
2039:
2029:, retrieved
2022:
2012:
2004:
2000:
1995:
1984:
1976:
1971:
1963:
1957:
1924:. Retrieved
1910:
1906:
1897:
1886:. Retrieved
1880:
1822:
1811:. Retrieved
1805:
1751:
1740:. Retrieved
1734:
1704:
1694:
1688:
1677:. Retrieved
1672:
1666:
1649:
1624:
1618:
1605:
1594:. Retrieved
1590:the original
1569:
1565:
1552:
1530:(2): 77–79.
1527:
1521:
1515:
1502:. Retrieved
1484:
1471:
1465:. Retrieved
1437:
1430:
1402:
1395:
1384:
1289:
1280:
1278:
1267:
1252:
1245:
1221:
1210:
1206:
1136:German mile
1090:Matthiessen
963:
953:
951:
942:
936:
933:
928:
901:
886:
877:
873:
865:
857:
853:
809:
797:
774:
692:
682:of the ohm:
675:
657:
645:
642:
628:
585:
229:
197:
168:
164:
162:
121:
116:
82:Unit of
26:
1836:Thomson, W.
1765:Thomson, W.
1718:Thomson, W.
1627:(5): 1–20.
1370:Resistivity
979:Definition
805:integration
703:Joule's law
662:(S) is the
224:multimeters
100:Named after
71:Unit system
58: 1917
2463:Categories
2153:Base units
2056:2018-11-22
2031:2017-02-26
1926:2023-12-23
1888:2014-02-27
1813:2014-02-27
1742:2014-02-27
1679:2014-02-27
1596:2014-02-27
1504:2021-01-31
1479:(85 pages)
1472:Reference
1467:2021-01-31
1274:IEEE 260.1
941:defined a
822:, ohm for
684:1 S = 1 Ω.
680:reciprocal
672:admittance
638:thermistor
622:(kg), and
214:Definition
189:telegraphy
2479:Georg Ohm
2296:steradian
2211:becquerel
1586:145557228
1572:: 48–63.
1412:cite book
1213:metrology
943:practical
902:In 1861,
897:metrology
699:Ohm's law
634:resistors
554:⋅
523:⋅
490:⋅
454:⋅
430:⋅
392:⋅
253:Ω
185:Georg Ohm
167:(symbol:
115:1 Ω
104:Georg Ohm
2448:Category
2403:See also
2176:kilogram
2145:SI units
1946:(1911).
1675:(1): 3–4
1613:(1860).
1498:Archived
1458:Archived
1343:See also
1329:alt code
1304:OHM SIGN
1301:Ω
1285:RKM code
1232:kilogram
1230:and the
985:Remarks
695:resistor
620:kilogram
208:kilogram
206:and the
2364:hectare
2349:decibel
2291:sievert
2286:siemens
2216:coulomb
2166:candela
1956:(ed.).
1629:Bibcode
1532:Bibcode
1318:Ω
1291:Unicode
1175:Statohm
1149:⁄
1126:⁄
1113:Varley
1103:⁄
1053:0.9537
1038:0.9191
1024:0.6367
1010:0.3202
996:0.3048
924:Thomson
920:Maxwell
850:History
789:voltage
787:is the
660:siemens
616:coulomb
588:siemens
179:in the
2379:minute
2339:dalton
2281:radian
2276:pascal
2266:newton
2191:second
2171:kelvin
2161:ampere
1907:Nature
1584:
1566:Osiris
1454:NSPUE3
1452:
1315:
1313:U+03A9
1298:
1296:U+2126
1272:, the
1242:Symbol
1228:ampere
1141:57.44
1118:25.61
1095:13.59
1069:1.000
836:ampere
775:where
631:linear
610:(Wb),
596:second
236:ampere
204:ampere
117:in ...
92:Symbol
18:Kilohm
2394:tonne
2389:neper
2374:litre
2316:weber
2301:tesla
2256:lumen
2251:katal
2246:joule
2241:hertz
2236:henry
2226:farad
2181:metre
1952:. In
1582:S2CID
1568:. 2.
1562:(PDF)
1461:(PDF)
1450:CODEN
1442:(PDF)
1333:⌥ Opt
1270:ASCII
1263:power
1182:8.987
1160:Abohm
1066:1863
976:Unit
954:legal
626:(m).
624:meter
618:(C),
614:(J),
612:joule
608:weber
606:(H),
604:henry
602:(F),
600:farad
598:(s),
594:(W),
590:(S),
173:omega
2369:hour
2311:watt
2306:volt
2231:gray
2186:mole
1422:link
1418:link
1259:watt
922:and
916:BAAS
838:for
834:and
830:for
828:volt
818:for
816:watt
701:and
670:and
658:The
592:watt
232:volt
163:The
2344:day
2271:ohm
2261:lux
2050:W3C
2003:in
1915:doi
1637:doi
1625:186
1574:doi
1540:doi
1187:787
1184:551
1166:10
947:CGS
929:ohm
676:ohm
666:of
165:ohm
42:ohm
2465::
2048:.
2021:,
1935:^
1911:30
1909:.
1905:.
1866:;
1862:;
1858:;
1854:;
1850:;
1846:;
1842:;
1838:;
1834:;
1830:;
1799:;
1795:;
1791:;
1787:;
1783:;
1779:;
1775:;
1771:;
1767:;
1763:;
1759:;
1728:;
1724:;
1720:;
1716:;
1712:;
1671:.
1665:.
1657:;
1635:.
1617:.
1580:.
1564:.
1538:.
1528:50
1526:.
1414:}}
1410:{{
1192:10
1128:16
1105:16
952:A
931:.
826:,
705::
518:kg
425:kg
370:Wb
242:.
144:kg
76:SI
55:c.
2137:e
2130:t
2123:v
2059:.
1929:.
1917::
1891:.
1816:.
1745:.
1682:.
1673:1
1643:.
1639::
1631::
1599:.
1576::
1570:9
1546:.
1542::
1534::
1507:.
1424:)
1406:.
1337:Z
1335:+
1323:(
1281:R
1190:Ă—
1151:6
1147:1
1124:1
1101:1
840:I
832:V
824:R
820:P
793:I
785:V
781:R
777:P
761:,
758:R
753:2
749:I
745:=
740:R
735:2
731:V
725:=
722:I
719:V
716:=
713:P
565:2
560:A
548:3
543:s
534:2
529:m
510:=
501:2
496:A
485:s
480:J
474:=
465:2
460:C
449:s
441:2
436:m
417:=
409:2
404:C
397:s
387:J
379:=
373:C
364:=
358:s
355:H
349:=
343:F
340:s
334:=
328:W
323:2
318:V
310:=
302:2
297:A
292:W
286:=
280:S
277:1
271:=
265:A
262:V
256:=
169:Ω
156:A
154:â‹…
152:s
150:â‹…
148:m
146:â‹…
95:Ω
36:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
