313:
2831:
1862:
49:
1677:
686:
Prior to 1948, various standards for luminous intensity were in use in a number of countries. These were typically based on the brightness of the flame from a "standard candle" of defined composition, or the brightness of an incandescent filament of specific design. One of the best-known of these was
722:
In practice, realizing a standard based on Violle's proposal turned out to be more difficult than expected. Impurities on the surface of the platinum could directly affect its emissivity, and in addition impurities could affect the luminous intensity by altering the melting point. Over the following
1621:
For the purpose of measuring illumination, the candela is not a practical unit, as it only applies to idealized point light sources, each approximated by a source small compared to the distance from which its luminous radiation is measured, also assuming that it is done so in the absence of other
831:
The definition describes how to produce a light source that (by definition) emits one candela, but does not specify the luminous efficiency function for weighting radiation at other frequencies. Such a source could then be used to calibrate instruments designed to measure luminous intensity with
457:
673:
714:
at its melting point (or freezing point). The resulting unit of intensity, called the "violle", was roughly equal to 60 English candlepower. Platinum was convenient for this purpose because it had a high enough melting point, was not prone to
60:(green) luminous efficiency functions. The photopic includes the CIE 1931 standard (solid), the Judd–Vos 1978 modified data (dashed), and the Sharpe, Stockman, Jagla & Jägle 2005 data (dotted). The horizontal axis is wavelength in nm.
294:
1857:{\displaystyle {\text{illuminance at point }}\mathbf {r} {\text{ on }}dA{\text{, }}E_{\mathrm {v} }(\mathbf {r} )=\sum _{i}{{\frac {|\mathbf {\hat {a}} \cdot (\mathbf {r} -\mathbf {r} _{i})|}{|\mathbf {r} -\mathbf {r} _{i}|^{3}}}I_{i}}.}
744:(International Commission on Illumination) and the CIPM proposed a "new candle" based on this concept, with value chosen to make it similar to the earlier unit candlepower. The decision was promulgated by the CIPM in 1946:
719:, and could be obtained in pure form. Violle showed that the intensity emitted by pure platinum was strictly dependent on its temperature, and so platinum at its melting point should have a consistent luminous intensity.
210:
emits light with a luminous intensity of roughly one candela. If emission in some directions is blocked by an opaque barrier, the emission would still be approximately one candela in the directions that are not obscured.
350:
832:
reference to a specified luminous efficiency function. An appendix to the SI Brochure makes it clear that the luminous efficiency function is not uniquely specified, but must be selected to fully define the candela.
1943:
343:. At other frequencies, more radiant intensity is required to achieve the same luminous intensity, according to the frequency response of the human eye. The luminous intensity for light of a particular wavelength
1595:
574:
1630:
in lm/m (lux). However, if designing illumination from many point light sources, like light bulbs, of known approximate omnidirectionally uniform intensities, the contributions to illuminance from
531:
2248:
764:. In 1967 the 13th CGPM removed the term "new candle" and gave an amended version of the candela definition, specifying the atmospheric pressure applied to the freezing platinum:
2107:
723:
half century various scientists tried to make a practical intensity standard based on incandescent platinum. The successful approach was to suspend a hollow shell of
1607:
of the lamp—the full vertex angle of the emission cone. For example, a lamp that emits 590 cd with a radiation angle of 40° emits about 224 lumens. See
203:
740:
835:
The arbitrary (1/683) term was chosen so that the new definition would precisely match the old definition. Although the candela is now defined in terms of the
1878:
2806:
247:
2454:
for the definition of the candela and associated derived units for photometric and radiometric quantities in the
International System of Units (SI)"
878:
2215:
1515:
1980:
of 555 nm in air, which is yellowish-green light approximately at the peak of human visual response. The color can be approximated on an
2279:
2101:
2860:
677:
Focused into a 20° beam (0.095 steradians), the same light bulb would have an intensity of around 18,000 cd or 18 kcd within the beam.
2522:
2357:
2174:
452:{\displaystyle I_{\mathrm {v} }(\lambda )=683.002\ \mathrm {lm/W} \cdot {\overline {y}}(\lambda )\cdot I_{\mathrm {e} }(\lambda ),}
668:{\displaystyle I_{\text{V}}={\frac {1700\ {\text{lm}}}{4\pi \ {\text{sr}}}}\approx 135\ {\text{lm}}/{\text{sr}}=135\ {\text{cd}}.}
2712:
2325:"Platinum and the Standard of Light: A Selective Review of Proposals Which Led to an International Unit of Luminous Intensity"
780:
In 1979, because of the difficulties in realizing a Planck radiator at high temperatures and the new possibilities offered by
2816:
2068:
752:
is such that the brightness of the full radiator at the temperature of solidification of platinum is 60 new candles per
557:
71:
1437:
recommend that photometric quantities be denoted with a subscript "v" (for "visual") to avoid confusion with radiometric or
2531:
179:
788:
The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency
871:
537:
199:
498:
839:(an SI base unit) and the watt (a derived SI unit), the candela remains a base unit of the SI system, by definition.
1674:
being measured, and provided that all light sources lie in the same half-space divided by the plane of this area,
2770:
1058:
289:
31:
1614:
If the source emits light uniformly in all directions, the flux can be found by multiplying the intensity by 4
2811:
864:
843:
2855:
2515:
1434:
2222:
2088:
202:, the model of the sensitivity of the human eye to different wavelengths, standardized by the CIE and
2266:
1406:
732:
2796:
1422:
1381:
1347:
973:
735:
that depends on the temperature and is not sensitive to details of how the device is constructed.
1003:
474:
175:
86:
2162:
250:(CGPM) redefined the candela in 2018. The new definition, which took effect on 20 May 2019, is:
540:. If more than one wavelength is present (as is usually the case), one must integrate over the
2834:
2720:
2508:
2373:
2353:
2275:
2170:
2097:
1665:
1302:
1252:
1175:
1135:
800:
772:
square metre of a black body at the temperature of freezing platinum under a pressure of
760:
It was then ratified in 1948 by the 9th CGPM which adopted a new name for this unit, the
753:
492:
255:
187:
2347:
2144:
1631:
332:
2587:
2274:(9th ed.), International Bureau of Weights and Measures, December 2022, p. 135,
2072:
920:
724:
340:
336:
283:
57:
53:
2221:. Versailles: Bureau International des Poids et Mesures. 13 November 2018. Archived from
2449:
312:
186:
emitted by a light source in a particular direction. Luminous intensity is analogous to
2740:
2672:
768:
The candela is the luminous intensity, in the perpendicular direction, of a surface of
219:
2035:
687:
the
English standard of candlepower. One candlepower was the light produced by a pure
335:
for bright conditions, is most sensitive near this frequency. Under these conditions,
2849:
2801:
2725:
2662:
2652:
2324:
1953:
1497:
964:
727:
with a small hole in it in a bath of molten platinum. The shell (cavity) serves as a
320:
1421:" are for length, time and luminous intensity respectively, not the symbols for the
2745:
2702:
2687:
2642:
2622:
2539:
2479:
2066:
Sharpe, Stockman, Jagla & Jägle (2005) 2-deg V*(l) luminous efficiency function
1509:
1295:
980:
940:
935:
842:
The 26th CGPM approved the modern definition of the candela in 2018 as part of the
707:
692:
561:
2065:
2420:
2140:
ISO/CIE 23539:2023 CIE TC 2-93 Photometry — The CIE system of physical photometry
2049:
2021:
2617:
2572:
2148:
1957:
1627:
1623:
1090:
1036:
846:, which redefined the SI base units in terms of fundamental physical constants.
700:
696:
234:
228:
183:
157:
136:
2216:"Convocation of the General Conference on Weights and Measures (26th meeting)"
1977:
1386:
1190:
1081:
781:
728:
688:
191:
2682:
2597:
1043:
984:
824:
716:
568:
328:
195:
17:
2138:
194:
of light in the source's spectrum, the contribution of each wavelength is
30:
This article is about the unit of luminous intensity. For other uses, see
2562:
711:
541:
534:
2294:
2190:
1483:
Relationships between luminous intensity, luminous flux, and illuminance
2750:
2735:
2677:
2607:
2602:
2122:
691:
candle weighing one sixth of a pound and burning at a rate of 120
48:
1938:{\displaystyle E_{\mathrm {v} }(r)={\frac {I_{\mathrm {v} }}{r^{2}}}.}
1455:
1453:
1451:
553:
A common candle emits light with roughly 1 cd luminous intensity.
2765:
2667:
2577:
2557:
2547:
2084:
1438:
836:
207:
273:, to be 683 when expressed in the unit lm W, which is equal to
2167:
Color
Science: Concepts and Methods, Quantitative Data and Formulae
710:
had proposed a standard based on the light emitted by 1 cm of
254:
The candela is defined by taking the fixed numerical value of the
2780:
2775:
2760:
2637:
2632:
2627:
2612:
2567:
2124:
CIE S 017:2020 ILV: International
Lighting Vocabulary, 2nd edition
1952:
Like other SI units, the candela can also be modified by adding a
1079:
source area. The candela per square metre is sometimes called the
795:
564:; if that light is radiated equally in all directions (i.e. over 4
327:, corresponding to a wavelength of about 555 nanometres. The
324:
311:
2755:
2697:
2692:
2426:
1981:
1608:
1320:
1314:
1272:
1266:
820:
2504:
281:, where the kilogram, metre and second are defined in terms of
2730:
2657:
2647:
2249:"Mise en pratique for the definition of the candela in the SI"
2050:"Judd–Vos modified CIE 2-deg photopic luminosity curve (1978)"
1985:
1634:
being additive, it is mathematically estimated as follows. If
1367:
Luminous efficacy normalized by the maximum possible efficacy
1111:
1105:
784:, the 16th CGPM adopted a new definition of the candela:
706:
A better standard for luminous intensity was needed. In 1884,
190:, but instead of simply adding up the contributions of every
2500:
1376:
76:
2486:. Bureau International des Poids et Mesures. 22 March 2021
2460:. Bureau International des Poids et Mesures. 22 March 2021
1618:: a uniform 1 candela source emits 12.6 lumens.
1590:{\displaystyle \Phi _{\mathrm {v} }=I_{\mathrm {v} }2\pi }
2349:
2480:"Units for photochemical and photobiological quantities"
1864:
In the case of a single point light source of intensity
1443:
USA Standard Letter
Symbols for Illuminating Engineering
226:. The old name "candle" is still sometimes used, as in
502:
501:
1881:
1680:
1518:
577:
353:
339:
dominates the visual perception of our eyes over the
695:
544:
of wavelengths to get the total luminous intensity.
2789:
2711:
2586:
2538:
1626:is incident light on a sensor of finite area, i.e.
143:
122:
100:
92:
82:
70:
65:
41:
1937:
1856:
1589:
667:
525:
451:
1960:, for example millicandela (mcd) for 10 candela.
1758:
526:{\textstyle \textstyle {\overline {y}}(\lambda )}
1622:light sources. What gets directly measured by a
1496:(in candelas) in a well-defined cone, the total
2429:Reference on Constants, Units, and Uncertainty
2516:
2318:
2316:
1487:If a source emits a known luminous intensity
872:
8:
2402:16th CGPM Resolution 3, CR, 100 (1979), and
2385:13th CGPM Resolution 5, CR, 104 (1967), and
2352:. U. S. Department of Commerce. p. 18.
2085:International Bureau of Weights and Measures
1342:Ratio of luminous flux to power consumption
1075:Luminous flux per unit solid angle per unit
2807:Historical definitions of the SI base units
2036:"CIE (1931) 2-deg color matching functions"
2523:
2509:
2501:
1611:for emission angles of some common lamps.
879:
865:
855:
248:General Conference on Weights and Measures
182:(SI). It measures luminous power per unit
38:
1924:
1913:
1912:
1906:
1887:
1886:
1880:
1844:
1831:
1826:
1819:
1814:
1805:
1800:
1793:
1784:
1779:
1770:
1753:
1752:
1747:
1744:
1743:
1737:
1722:
1712:
1711:
1702:
1691:
1686:
1681:
1679:
1668:to the illuminated elemental opaque area
1573:
1539:
1538:
1524:
1523:
1517:
955:The lumen second is sometimes called the
657:
643:
638:
633:
616:
600:
591:
582:
576:
503:
500:
430:
429:
403:
391:
384:
359:
358:
352:
2364:(NIST Special Publication 330, 1991 ed.)
2061:
2059:
741:Commission Internationale de l'Éclairage
258:of monochromatic radiation of frequency
2013:
1969:
1875:and normally incident, this reduces to
1398:
2090:The International System of Units (SI)
2022:"CIE Scotopic luminosity curve (1951)"
900:
896:
893:
890:
7:
2169:(2nd ed.). Wiley-Interscience.
2110:from the original on 18 October 2021
1459:Alternative symbols sometimes seen:
776: newtons per square metre.
1914:
1888:
1713:
1540:
1525:
1520:
1475:for luminous efficacy of a source.
1405:The symbols in this column denote
699:, a unit based on the output of a
431:
396:
388:
385:
360:
25:
2268:The International System of Units
104:
2830:
2829:
2421:"Base unit definitions: Candela"
1976:This frequency corresponds to a
1815:
1806:
1780:
1771:
1755:
1723:
1687:
1108:(= lumen per square metre)
571:), it will have an intensity of
47:
2295:"Hefner unit, or Hefner candle"
1996:
1649:th source of uniform intensity
319:The frequency chosen is in the
2817:System of units of measurement
1900:
1894:
1827:
1801:
1794:
1790:
1767:
1748:
1727:
1719:
1584:
1581:
1567:
1552:
998:Luminous energy per unit time
558:compact fluorescent light bulb
519:
513:
443:
437:
419:
413:
372:
366:
1:
1229:lumen second per cubic metre
1021:(= lumen per steradian)
770:1 / 600 000
232:and the modern definition of
180:International System of Units
27:SI unit of luminous intensity
1211:Time-integrated illuminance
538:luminous efficiency function
508:
408:
200:luminous efficiency function
2861:Units of luminous intensity
2374:Proceedings of the 9th CGPM
2323:Cottington, Ian E. (1986).
2149:10.25039/IS0.CIE.23539.2023
1445:USAS Z7.1-1967, Y10.18-1967
2877:
2195:Merriam-Webster Dictionary
2191:"Candlepower – Definition"
1683:illuminance at point
1294:Ratio of luminous flux to
850:SI photometric light units
560:puts out around 1700
29:
2825:
2071:27 September 2007 at the
1441:quantities. For example:
1371:
1346:
1301:
1251:
1215:
1174:
1134:
1089:
1042:
1002:
963:
919:
914:
911:
908:
905:
118:
46:
2771:minute and second of arc
2376:, 1948, page 54 (French)
2346:Barry N. Taylor (1992).
1956:that multiplies it by a
1216:Luminous energy density
1063:cd/m (= lm/(sr⋅m))
1059:candela per square metre
859:SI photometry quantities
32:Candela (disambiguation)
2812:2019 revision of the SI
2165:; Stiles, W.S. (1982).
1645:is the position of the
1471:for luminous flux, and
1435:Standards organizations
1425:litre, tesla and joule.
1350:, luminous coefficient
1151:lumen per square metre
1035:Luminous flux per unit
844:2019 revision of the SI
2484:SI Brochure Appendix 3
2458:SI Brochure Appendix 2
2329:Platinum Metals Review
2247:BIPM (22 March 2021).
1939:
1858:
1591:
829:
778:
758:
669:
527:
453:
316:
305:
1940:
1859:
1592:
1463:for luminous energy,
1138:, luminous emittance
803:in that direction of
786:
766:
746:
670:
528:
454:
315:
252:
126:international candles
2713:Other accepted units
2228:on 19 September 2019
2127:(2nd ed.). CIE.
1879:
1678:
1516:
733:black-body radiation
575:
499:
351:
2797:Conversion of units
1664:is the unit vector
1348:Luminous efficiency
887:
113:... is equal to ...
66:General information
2590:with special names
1935:
1854:
1742:
1587:
1004:Luminous intensity
990:lm (= cd⋅sr)
856:
665:
523:
522:
475:luminous intensity
449:
317:
176:luminous intensity
151:
145:
130:
124:
87:luminous intensity
2843:
2842:
2721:astronomical unit
2281:978-92-822-2272-0
2143:. ISO/CIE. 2023.
2103:978-92-822-2272-0
1930:
1838:
1761:
1733:
1705:
1694:
1684:
1395:
1394:
1303:Luminous efficacy
1253:Luminous efficacy
1176:Luminous exposure
1136:Luminous exitance
967:, luminous power
801:radiant intensity
754:square centimetre
748:The value of the
660:
656:
646:
636:
632:
622:
619:
615:
603:
599:
585:
511:
493:radiant intensity
411:
383:
256:luminous efficacy
188:radiant intensity
174:) is the unit of
164:
163:
101:Conversions
16:(Redirected from
2868:
2833:
2832:
2525:
2518:
2511:
2502:
2496:
2495:
2493:
2491:
2476:
2470:
2469:
2467:
2465:
2452:Mise en pratique
2446:
2440:
2439:
2437:
2435:
2417:
2411:
2400:
2394:
2383:
2377:
2371:
2365:
2363:
2343:
2337:
2336:
2320:
2311:
2310:
2308:
2306:
2291:
2285:
2284:
2273:
2263:
2257:
2256:
2244:
2238:
2237:
2235:
2233:
2227:
2220:
2212:
2206:
2205:
2203:
2201:
2187:
2181:
2180:
2159:
2153:
2152:
2135:
2129:
2128:
2118:
2112:
2111:
2096:(9th ed.),
2095:
2081:
2075:
2063:
2054:
2053:
2046:
2040:
2039:
2032:
2026:
2025:
2018:
2002:
2000:
1999:
1995:
1991:
1974:
1944:
1942:
1941:
1936:
1931:
1929:
1928:
1919:
1918:
1917:
1907:
1893:
1892:
1891:
1871:, at a distance
1863:
1861:
1860:
1855:
1850:
1849:
1848:
1839:
1837:
1836:
1835:
1830:
1824:
1823:
1818:
1809:
1804:
1798:
1797:
1789:
1788:
1783:
1774:
1763:
1762:
1754:
1751:
1745:
1741:
1726:
1718:
1717:
1716:
1706:
1703:
1695:
1692:
1690:
1685:
1682:
1673:
1663:
1657:
1644:
1632:incoherent light
1617:
1602:
1596:
1594:
1593:
1588:
1577:
1545:
1544:
1543:
1530:
1529:
1528:
1507:
1495:
1476:
1474:
1470:
1466:
1462:
1457:
1446:
1432:
1426:
1403:
1355:
1310:
1262:
1226:
1187:
1148:
1102:
1055:
1015:
983:(= candela
977:
932:
888:
881:
874:
867:
860:
818:
816:
815:
812:
809:
798:
793:
775:
771:
674:
672:
671:
666:
661:
658:
654:
647:
644:
642:
637:
634:
630:
623:
621:
620:
617:
613:
605:
604:
601:
597:
592:
587:
586:
583:
567:
532:
530:
529:
524:
512:
504:
490:
472:
458:
456:
455:
450:
436:
435:
434:
412:
404:
399:
395:
381:
365:
364:
363:
321:visible spectrum
280:
276:
265:
263:
156:
152:
146:
135:
131:
125:
51:
39:
21:
2876:
2875:
2871:
2870:
2869:
2867:
2866:
2865:
2846:
2845:
2844:
2839:
2821:
2802:Metric prefixes
2785:
2707:
2589:
2582:
2534:
2529:
2499:
2489:
2487:
2478:
2477:
2473:
2463:
2461:
2448:
2447:
2443:
2433:
2431:
2419:
2418:
2414:
2401:
2397:
2393:, 43–44 (1968).
2384:
2380:
2372:
2368:
2360:
2345:
2344:
2340:
2322:
2321:
2314:
2304:
2302:
2293:
2292:
2288:
2282:
2271:
2265:
2264:
2260:
2246:
2245:
2241:
2231:
2229:
2225:
2218:
2214:
2213:
2209:
2199:
2197:
2189:
2188:
2184:
2177:
2161:
2160:
2156:
2137:
2136:
2132:
2120:
2119:
2115:
2104:
2093:
2087:(20 May 2019),
2083:
2082:
2078:
2073:Wayback Machine
2064:
2057:
2048:
2047:
2043:
2034:
2033:
2029:
2020:
2019:
2015:
2011:
2006:
2005:
1997:
1993:
1989:
1975:
1971:
1966:
1950:
1920:
1908:
1882:
1877:
1876:
1869:
1840:
1825:
1813:
1799:
1778:
1746:
1707:
1676:
1675:
1669:
1659:
1655:
1650:
1643:
1635:
1615:
1605:radiation angle
1598:
1534:
1519:
1514:
1513:
1506:
1500:
1494:
1488:
1485:
1480:
1479:
1472:
1468:
1464:
1460:
1458:
1449:
1433:
1429:
1404:
1400:
1391:
1353:
1308:
1258:
1255:(of radiation)
1225:
1219:
1186:
1180:
1170:from a surface
1147:
1141:
1101:
1095:
1054:
1048:
1027:(= lm/sr)
1014:
1008:
976:
970:
931:
925:
921:Luminous energy
898:
886:
885:
858:
852:
813:
810:
807:
806:
804:
799:and that has a
791:
789:
773:
769:
725:thorium dioxide
684:
606:
593:
578:
573:
572:
565:
550:
497:
496:
484:
478:
466:
460:
425:
354:
349:
348:
341:scotopic vision
337:photopic vision
310:
301:
278:
274:
272:
261:
259:
244:
206:. A common wax
154:
150:
144:
133:
129:
123:
61:
35:
28:
23:
22:
15:
12:
11:
5:
2874:
2872:
2864:
2863:
2858:
2848:
2847:
2841:
2840:
2838:
2837:
2826:
2823:
2822:
2820:
2819:
2814:
2809:
2804:
2799:
2793:
2791:
2787:
2786:
2784:
2783:
2778:
2773:
2768:
2763:
2758:
2753:
2748:
2743:
2738:
2733:
2728:
2723:
2717:
2715:
2709:
2708:
2706:
2705:
2700:
2695:
2690:
2685:
2680:
2675:
2670:
2665:
2660:
2655:
2650:
2645:
2640:
2635:
2630:
2625:
2620:
2615:
2610:
2608:degree Celsius
2605:
2600:
2594:
2592:
2588:Derived units
2584:
2583:
2581:
2580:
2575:
2570:
2565:
2560:
2555:
2550:
2544:
2542:
2536:
2535:
2530:
2528:
2527:
2520:
2513:
2505:
2498:
2497:
2471:
2441:
2412:
2395:
2378:
2366:
2358:
2338:
2312:
2286:
2280:
2258:
2239:
2207:
2182:
2175:
2154:
2130:
2113:
2102:
2076:
2055:
2041:
2027:
2012:
2010:
2007:
2004:
2003:
1990:rgb(120,255,0)
1968:
1967:
1965:
1962:
1949:
1946:
1934:
1927:
1923:
1916:
1911:
1905:
1902:
1899:
1896:
1890:
1885:
1867:
1853:
1847:
1843:
1834:
1829:
1822:
1817:
1812:
1808:
1803:
1796:
1792:
1787:
1782:
1777:
1773:
1769:
1766:
1760:
1757:
1750:
1740:
1736:
1732:
1729:
1725:
1721:
1715:
1710:
1701:
1698:
1693: on
1689:
1653:
1639:
1586:
1583:
1580:
1576:
1572:
1569:
1566:
1563:
1560:
1557:
1554:
1551:
1548:
1542:
1537:
1533:
1527:
1522:
1504:
1492:
1484:
1481:
1478:
1477:
1447:
1427:
1397:
1396:
1393:
1392:
1390:
1389:
1384:
1379:
1373:
1369:
1368:
1365:
1360:
1358:
1356:
1351:
1344:
1343:
1340:
1323:
1317:
1311:
1306:
1305:(of a source)
1299:
1298:
1292:
1275:
1269:
1263:
1256:
1249:
1248:
1246:
1233:
1230:
1227:
1223:
1217:
1213:
1212:
1209:
1196:
1193:
1188:
1184:
1178:
1172:
1171:
1166:Luminous flux
1164:
1155:
1152:
1149:
1145:
1139:
1132:
1131:
1126:Luminous flux
1124:
1115:
1114:(= lm/m)
1109:
1103:
1099:
1093:
1087:
1086:
1073:
1064:
1061:
1056:
1052:
1046:
1040:
1039:
1033:
1028:
1022:
1016:
1012:
1006:
1000:
999:
996:
991:
988:
978:
972:
968:
961:
960:
953:
944:
938:
933:
929:
923:
917:
916:
913:
910:
907:
903:
902:
899:
895:
892:
884:
883:
876:
869:
861:
857:
851:
848:
683:
680:
679:
678:
675:
664:
653:
650:
641:
629:
626:
612:
609:
596:
590:
581:
554:
549:
546:
521:
518:
515:
510:
507:
482:
464:
448:
445:
442:
439:
433:
428:
424:
421:
418:
415:
410:
407:
402:
398:
394:
390:
387:
380:
377:
374:
371:
368:
362:
357:
309:
306:
299:
270:
243:
240:
162:
161:
148:
141:
140:
127:
120:
119:
116:
115:
110:
103:
102:
98:
97:
94:
90:
89:
84:
80:
79:
74:
68:
67:
63:
62:
52:
44:
43:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
2873:
2862:
2859:
2857:
2856:SI base units
2854:
2853:
2851:
2836:
2828:
2827:
2824:
2818:
2815:
2813:
2810:
2808:
2805:
2803:
2800:
2798:
2795:
2794:
2792:
2788:
2782:
2779:
2777:
2774:
2772:
2769:
2767:
2764:
2762:
2759:
2757:
2754:
2752:
2749:
2747:
2744:
2742:
2741:degree of arc
2739:
2737:
2734:
2732:
2729:
2727:
2724:
2722:
2719:
2718:
2716:
2714:
2710:
2704:
2701:
2699:
2696:
2694:
2691:
2689:
2686:
2684:
2681:
2679:
2676:
2674:
2671:
2669:
2666:
2664:
2661:
2659:
2656:
2654:
2651:
2649:
2646:
2644:
2641:
2639:
2636:
2634:
2631:
2629:
2626:
2624:
2621:
2619:
2616:
2614:
2611:
2609:
2606:
2604:
2601:
2599:
2596:
2595:
2593:
2591:
2585:
2579:
2576:
2574:
2571:
2569:
2566:
2564:
2561:
2559:
2556:
2554:
2551:
2549:
2546:
2545:
2543:
2541:
2537:
2533:
2526:
2521:
2519:
2514:
2512:
2507:
2506:
2503:
2485:
2481:
2475:
2472:
2459:
2455:
2453:
2445:
2442:
2430:
2428:
2422:
2416:
2413:
2409:
2405:
2399:
2396:
2392:
2388:
2382:
2379:
2375:
2370:
2367:
2361:
2359:0-941375-74-9
2355:
2351:
2350:
2342:
2339:
2334:
2330:
2326:
2319:
2317:
2313:
2301:. 30 May 2007
2300:
2296:
2290:
2287:
2283:
2277:
2270:
2269:
2262:
2259:
2254:
2250:
2243:
2240:
2224:
2217:
2211:
2208:
2196:
2192:
2186:
2183:
2178:
2176:0-471-02106-7
2172:
2168:
2164:
2158:
2155:
2150:
2146:
2142:
2141:
2134:
2131:
2126:
2125:
2117:
2114:
2109:
2105:
2099:
2092:
2091:
2086:
2080:
2077:
2074:
2070:
2067:
2062:
2060:
2056:
2051:
2045:
2042:
2037:
2031:
2028:
2023:
2017:
2014:
2008:
1987:
1984:display with
1983:
1979:
1973:
1970:
1963:
1961:
1959:
1955:
1954:metric prefix
1947:
1945:
1932:
1925:
1921:
1909:
1903:
1897:
1883:
1874:
1870:
1851:
1845:
1841:
1832:
1820:
1810:
1785:
1775:
1764:
1738:
1734:
1730:
1708:
1699:
1696:
1672:
1667:
1662:
1656:
1648:
1642:
1638:
1633:
1629:
1625:
1619:
1612:
1610:
1606:
1601:
1578:
1574:
1570:
1564:
1561:
1558:
1555:
1549:
1546:
1535:
1531:
1511:
1503:
1499:
1498:luminous flux
1491:
1482:
1456:
1454:
1452:
1448:
1444:
1440:
1436:
1431:
1428:
1424:
1420:
1416:
1412:
1408:
1402:
1399:
1388:
1385:
1383:
1380:
1378:
1375:
1374:
1370:
1366:
1364:
1361:
1359:
1357:
1352:
1349:
1345:
1341:
1339:
1335:
1331:
1327:
1324:
1322:
1318:
1316:
1312:
1307:
1304:
1300:
1297:
1293:
1291:
1287:
1283:
1279:
1276:
1274:
1270:
1268:
1264:
1261:
1257:
1254:
1250:
1247:
1245:
1241:
1237:
1234:
1231:
1228:
1222:
1218:
1214:
1210:
1208:
1204:
1200:
1197:
1194:
1192:
1189:
1183:
1179:
1177:
1173:
1169:
1165:
1163:
1159:
1156:
1153:
1150:
1144:
1140:
1137:
1133:
1130:on a surface
1129:
1125:
1123:
1119:
1116:
1113:
1110:
1107:
1104:
1098:
1094:
1092:
1088:
1084:
1083:
1078:
1074:
1072:
1068:
1065:
1062:
1060:
1057:
1051:
1047:
1045:
1041:
1038:
1034:
1032:
1029:
1026:
1023:
1020:
1017:
1011:
1007:
1005:
1001:
997:
995:
992:
989:
986:
982:
979:
975:
969:
966:
965:Luminous flux
962:
958:
954:
952:
948:
945:
942:
939:
937:
934:
928:
924:
922:
918:
904:
889:
882:
877:
875:
870:
868:
863:
862:
854:
849:
847:
845:
840:
838:
833:
828:
826:
822:
802:
797:
785:
783:
777:
774:101 325
765:
763:
757:
755:
751:
745:
743:
742:
738:In 1937, the
736:
734:
730:
726:
720:
718:
713:
709:
704:
702:
698:
694:
690:
681:
676:
662:
651:
648:
639:
627:
624:
610:
607:
594:
588:
579:
570:
563:
559:
555:
552:
551:
547:
545:
543:
539:
536:
516:
505:
494:
488:
481:
476:
470:
463:
446:
440:
426:
422:
416:
405:
400:
392:
378:
375:
369:
355:
346:
342:
338:
334:
330:
326:
322:
314:
307:
304:
302:
298:
292:
291:
286:
285:
269:
257:
251:
249:
241:
239:
237:
236:
231:
230:
225:
221:
217:
212:
209:
205:
201:
197:
193:
189:
185:
181:
177:
173:
169:
159:
149:
142:
138:
128:
121:
117:
114:
111:
109:
105:
99:
95:
91:
88:
85:
81:
78:
75:
73:
69:
64:
59:
55:
50:
45:
40:
37:
33:
19:
2746:electronvolt
2552:
2488:. Retrieved
2483:
2474:
2462:. Retrieved
2457:
2451:
2444:
2434:27 September
2432:. Retrieved
2424:
2415:
2410:, 56 (1980).
2407:
2403:
2398:
2390:
2386:
2381:
2369:
2348:
2341:
2332:
2328:
2303:. Retrieved
2298:
2289:
2267:
2261:
2252:
2242:
2230:. Retrieved
2223:the original
2210:
2198:. Retrieved
2194:
2185:
2166:
2163:Wyszecki, G.
2157:
2139:
2133:
2123:
2121:CIE (2020).
2116:
2089:
2079:
2044:
2030:
2016:
1988:color value
1972:
1951:
1948:SI multiples
1872:
1865:
1670:
1660:
1651:
1646:
1640:
1636:
1620:
1613:
1604:
1599:
1512:is given by
1501:
1489:
1486:
1442:
1430:
1418:
1414:
1410:
1401:
1362:
1337:
1333:
1329:
1325:
1296:radiant flux
1289:
1285:
1281:
1277:
1259:
1243:
1239:
1235:
1220:
1206:
1202:
1198:
1181:
1167:
1161:
1157:
1142:
1127:
1121:
1117:
1096:
1080:
1076:
1070:
1066:
1049:
1030:
1024:
1018:
1009:
993:
956:
950:
946:
936:lumen second
926:
853:
841:
834:
830:
787:
779:
767:
761:
759:
749:
747:
739:
737:
731:, producing
721:
708:Jules Violle
705:
685:
556:A 25 W
486:
479:
468:
461:
347:is given by
344:
318:
296:
288:
282:
279:cd sr kg m s
267:
253:
245:
233:
227:
223:
215:
213:
171:
167:
165:
147:Hefner Kerze
112:
107:
83:Unit of
56:(black) and
36:
2305:25 February
2232:10 February
2200:15 February
1958:power of 10
1628:illuminance
1624:light meter
1091:Illuminance
1037:solid angle
701:Hefner lamp
697:Hefnerkerze
308:Explanation
235:candlepower
229:foot-candle
184:solid angle
72:Unit system
18:Megacandela
2850:Categories
2540:Base units
2404:Metrologia
2387:Metrologia
2009:References
1978:wavelength
1407:dimensions
1387:Radiometry
1382:Photometry
1372:See also:
1313:lumen per
1265:lumen per
1191:lux second
782:radiometry
750:new candle
729:black body
689:spermaceti
569:steradians
264:10 Hz
242:Definition
192:wavelength
106:1 cd
2683:steradian
2598:becquerel
2490:7 October
2464:7 October
2299:Sizes.com
1811:−
1776:−
1765:⋅
1759:^
1735:∑
1565:
1559:−
1550:π
1521:Φ
1077:projected
1044:Luminance
985:steradian
897:Dimension
891:Quantity
825:steradian
717:oxidation
625:≈
611:π
517:λ
509:¯
441:λ
423:⋅
417:λ
409:¯
401:⋅
370:λ
329:human eye
246:The 26th
214:The word
170:(symbol:
2835:Category
2790:See also
2563:kilogram
2532:SI units
2335:(2): 84.
2108:archived
2069:Archived
1128:incident
794:10
712:platinum
548:Examples
542:spectrum
535:photopic
196:weighted
153:≈
132:≈
58:scotopic
54:Photopic
2751:hectare
2736:decibel
2678:sievert
2673:siemens
2603:coulomb
2553:candela
1998:
1994:#78ff00
1992:or hex
1704:,
1603:is the
1417:" and "
1232:lm⋅s/m
1168:emitted
1019:candela
915:Symbol
909:Symbol
817:
805:
762:candela
682:History
533:is the
491:is the
473:is the
379:683.002
333:adapted
331:, when
275:cd sr W
216:candela
198:by the
178:in the
168:candela
160:
139:
42:candela
2766:minute
2726:dalton
2668:radian
2663:pascal
2653:newton
2578:second
2558:kelvin
2548:ampere
2356:
2278:
2173:
2100:
1666:normal
1658:, and
1597:where
1510:lumens
1439:photon
957:talbot
901:Notes
837:second
819:
693:grains
655:
631:
614:
598:
562:lumens
459:where
382:
224:candle
208:candle
108:in ...
93:Symbol
2781:tonne
2776:neper
2761:litre
2703:weber
2688:tesla
2643:lumen
2638:katal
2633:joule
2628:hertz
2623:henry
2613:farad
2568:metre
2272:(PDF)
2226:(PDF)
2219:(PDF)
2094:(PDF)
1964:Notes
1423:units
1195:lx⋅s
1154:lm/m
981:lumen
912:Name
906:Name
894:Unit
796:hertz
325:green
323:near
277:, or
220:Latin
2756:hour
2698:watt
2693:volt
2618:gray
2573:mole
2492:2023
2466:2023
2436:2010
2427:NIST
2425:The
2354:ISBN
2307:2009
2276:ISBN
2253:BIPM
2234:2019
2202:2015
2171:ISBN
2098:ISBN
1982:sRGB
1609:MR16
1413:", "
1315:watt
1267:watt
823:per
821:watt
595:1700
495:and
293:and
222:for
166:The
155:1.11
134:1.02
2731:day
2658:ohm
2648:lux
2145:doi
1986:CSS
1562:cos
1508:in
1467:or
1409:; "
1319:lm/
1271:lm/
1106:lux
1082:nit
943:⋅s
814:683
790:540
652:135
628:135
260:540
218:is
204:ISO
2852::
2482:.
2456:.
2423:.
2408:16
2406:,
2389:,
2333:30
2331:.
2327:.
2315:^
2297:.
2251:.
2193:.
2106:,
2058:^
2001:.
1671:dA
1450:^
1377:SI
1112:lx
1085:.
1025:cd
987:)
959:.
941:lm
827:.
703:.
659:cd
645:sr
635:lm
618:sr
602:lm
477:,
300:Cs
287:,
271:cd
266:,
238:.
172:cd
158:HK
137:cp
96:cd
77:SI
2524:e
2517:t
2510:v
2494:.
2468:.
2450:"
2438:.
2391:4
2362:.
2309:.
2255:.
2236:.
2204:.
2179:.
2151:.
2147::
2052:.
2038:.
2024:.
1933:.
1926:2
1922:r
1915:v
1910:I
1904:=
1901:)
1898:r
1895:(
1889:v
1884:E
1873:r
1868:v
1866:I
1852:.
1846:i
1842:I
1833:3
1828:|
1821:i
1816:r
1807:r
1802:|
1795:|
1791:)
1786:i
1781:r
1772:r
1768:(
1756:a
1749:|
1739:i
1731:=
1728:)
1724:r
1720:(
1714:v
1709:E
1700:A
1697:d
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