286:"Candlepower" is largely an obsolete term. However, people still sometimes use it to describe the luminous intensity of high powered flashlights and spotlights. Narrow-beamed lights of all sorts can have very high candlepower specifications, because candlepower measures the intensity of the light on a target, rather than the total amount of light it emits. A given lamp has a higher candlepower rating if its light is more tightly focused.
29:
273:
To measure the candlepower of a lamp, a person judged by eye the relative brightness of adjacent surfaces—one illuminated only by a standard lamp (or candle) and the other only by the lamp under test. They adjusted the distance of one of the lamps until the two surfaces appeared to be of equal
402:
220:(Germany). The majority redefined the candle in term of an electric lamp with a carbon filament. The Germans, however, dissented and decided to use a definition equal to 9/10 of the output of a
231:(International Commission for Illumination, commonly referred to as the CIE) redefined the international candle again in terms of a carbon filament
304:, have the very high candlepower ratings characteristic of narrow-beamed spotlights but, simultaneously, a wide unfocused distribution of light.
211:
155:
202:
544:
500:"Platinum and the Standard of Light - A Selective Review Of Proposals Which Led To An International Unit Of Luminous Intensity"
216:
318:
176:
pound (76 grams) and burns at a rate of 120 grains per hour (7.8 grams per hour). Spermaceti is a material from the heads of
534:
452:
460:
183:
At the time the UK established candlepower as a unit, the French standard of light was based on the illumination from a
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In 1909, several agencies met to establish an international standard. It was attended by representatives of the
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brightness. Then they calculated the candlepower of the lamp under test from the two distances and the
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now equates directly (1:1) to the number of candelas—an implicit increase from its old value.
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In 1937, the international candle was redefined again—against the luminous intensity of a
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57:
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539:
232:
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Candlepower is still used today in law. For example, it is presently used in the
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134:
of specific size and constituents. The historical candlepower is equal to 0.981
420:
480:
523:
193:
184:
476:
130:. It expresses levels of light intensity relative to the light emitted by a
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197:) at a defined rate. Ten standard candles equaled about one Carcel burner.
221:
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187:, which defined the illumination that emanates from a lamp burning pure
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97:
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which was to be 58.9 international candles per square centimetre.
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135:
106:
380:
131:
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The candlepower was based on the light emitted from a candle
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at Sizes.com Last revised: 27 June 2007. Accessed July 2007
455:
by Bill
Williams Edition: 2.3 - (2005) Accessed July 2007.
28:
250:
300:
Only a few artificial light sources, such as military
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unit is about 0.981 candela. In general modern use, a
370:
154:The term candlepower was originally defined in the
443:2003 Bob Sherman at Craftcave. Accessed July 2007.
180:, and was once used to make high-quality candles.
449:2004 by The Wolfstone Group. Accessed July 2007.
521:
461:"The genesis of incandescent lamp - manufacture"
421:"How Many? A Dictionary of Units of Measurement"
423:. University of North Carolina at Chapel Hill
297:and other lamps, including accessory lamps.
505:. Platinum Metals Review. pp. 30, (2)
497:
27:
465:Engineering Science and Education Journal
341:
339:
229:Commission Internationale de l'Eclairage
492:Measurement of the candlepower of lamps
418:
329:
268:
522:
458:
336:
217:Physikalische Technische Reichsanstalt
319:List of obsolete units of measurement
293:to define the legal requirements for
191:(obtained from the seed of the plant
498:Cottington, Ian E. (February 1986).
203:Laboratoire Central de l’Electricité
142:is sometimes used as a synonym for
13:
412:
162:, as the light produced by a pure
14:
556:
249:In 1948, the international unit (
49:international standard (obsolete)
242:at the freezing point of liquid
459:Coaton, J. R. (February 2002).
453:A History of Light and Lighting
403:California Vehicle Code § 25105
126:) is a unit of measurement for
395:
364:
1:
545:Obsolete units of measurement
281:
514:Metropolitan Gas Act of 1860
441:Candle History - Candlepower
419:Rowlett, Russ (2001-07-13).
373:"Frequently Asked Questions"
208:National Physical Laboratory
7:
535:Units of luminous intensity
307:
10:
561:
351:Merriam-Webster Dictionary
347:"Candlepower - Definition"
257:replaced candlepower. One
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447:Brief History Of Lighting
214:(United States), and the
160:Metropolitan Gas Act 1860
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71:
63:
53:
43:
38:
26:
21:
371:Peak Beam Systems, Inc.
405:, among other sections.
291:California Vehicle Code
477:10.1049/esej:20020103
483:on September 9, 2017
435:International candle
330:Notes and references
269:Calibration of lamps
212:Bureau of Standards
194:Brassica campestris
166:candle that weighs
138:. In modern usage,
109:(modern definition)
84:... is equal to ...
39:General information
16:Unit of measurement
276:inverse square law
128:luminous intensity
103:
95:
58:Luminous intensity
383:on 4 January 2015
233:incandescent lamp
113:
112:
72:Conversions
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504:
494:
489:
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479:. Archived from
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379:. Archived from
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302:photoflash bombs
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118:(abbreviated as
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413:Further reading
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227:In 1921, the
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185:Carcel burner
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507:. Retrieved
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485:. Retrieved
481:the original
471:. IEEE: 21.
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425:. Retrieved
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385:. Retrieved
381:the original
377:peakbeam.com
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354:. Retrieved
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324:Lumen (unit)
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288:
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178:sperm whales
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83:
78:
54:Unit of
387:15 February
356:15 February
263:candlepower
259:candlepower
222:Hefner lamp
140:candlepower
116:Candlepower
45:Unit system
22:Candlepower
524:Categories
509:2007-07-10
487:2007-07-10
427:2007-07-10
282:Modern use
210:(UK), the
164:spermaceti
77:1 cp
295:headlamps
240:blackbody
189:colza oil
158:, by the
540:Lighting
308:See also
244:platinum
136:candelas
98:SI units
530:Candles
314:Candela
255:candela
171:⁄
150:History
107:candela
144:candla
132:candle
79:in ...
64:Symbol
503:(PDF)
401:See
389:2015
358:2015
473:doi
122:or
526::
512:.
490:.
469:11
467:.
463:.
375:.
349:.
338:^
278:.
253:)
251:SI
235:.
224:.
146:.
124:CP
120:cp
105:1
67:cp
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430:.
391:.
360:.
173:6
169:1
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