Candela - Revision history

Jmdonev: 1 revision imported

2026-06-04T17:16:57Z

1 revision imported

← Older revision	Revision as of 17:16, 4 June 2026
(No difference)

Energy>Jmdonev at 17:20, 21 May 2026

2026-05-21T17:20:17Z

@@ Line 1: / Line 1: @@
 [[category: units]]
-<onlyinclude>The '''candela''' (cd) is the [[SI]] [[units|unit]] of [[luminous intensity]], which is a measure of [[power]] emitted from a light source.</onlyinclude> The definition for a candela is:<ref name=web1>NIST. ''Base unit definitions: Candela'' [Online] Available: http://physics.nist.gov/cuu/Units/candela.html </ref>
+<onlyinclude>The '''candela''' (cd) is one of the 7 base SI units: the [[SI]] [[units|unit]] of [[luminous intensity]]. It is a measure of [[power]] emitted from a light source.</onlyinclude> The current definition for a candela from May of 2019 is:<blockquote>''The candela is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540×10<sup>12</sup> Hz, K<sub>cd</sub>, to be 683 when expressed in the unit lm⋅W<sup>−1</sup>, <small>which is equal to cd⋅sr⋅W<sup>−1</sup>, or cd⋅sr⋅kg<sup>−1</sup>⋅m<sup>−2</sup>⋅s<sup>3</sup>, where the kilogram, meter and second are defined in terms of h, c and Δν<sub>Cs</sub>.</small><ref name="web1">NIST. ''Base unit definitions: Candela'' [Online] Available: http://physics.nist.gov/cuu/Units/candela.html </ref>''</blockquote>Candela is Latin for the word 'candle', and a typical candle's luminous intensity is actually about equal to one candela.<ref>SI Units Explained. ''Luminous Intensity'' [Online] Available: http://www.si-units-explained.info/luminosity/</ref>
-The luminous intensity, in a given direction, of a source that emits monochromatic [[radiation]] of [[frequency]] 540 x 10<sup>12</sup> [[hertz]] and that has a radiant intensity in that direction of 1/683 [[watt]] per steradian.
+== Significance of the Candela (''K<sub>cd</sub>)'' ==
-Candela is Latin for the word 'candle', and a typical candle's luminous intensity is actually about equal to one candela.<ref>SI Units Explained. ''Luminous Intensity'' [Online] Available: http://www.si-units-explained.info/luminosity/</ref>
+=== Candela vs. Lumen vs. Watt ===
-Visit Dr. Rowlett's [http://www.unc.edu/~rowlett/units/dictC.html#candela unit dictionary] to learn more about the candela, and learn more about luminous intensity [http://www.si-units-explained.info/luminosity/ here].
+=== Measuring ''only'' the light coming directly from the source to one's eyes (solid angle) ===
 ==References==
 {{reflist}}
 [[Category:Uploaded]]

Jmdonev: 1 revision imported

2016-02-18T04:31:22Z

1 revision imported

← Older revision	Revision as of 04:31, 18 February 2016
(No difference)

Jmdonev at 23:34, 3 February 2016

2016-02-03T23:34:42Z

← Older revision		Revision as of 23:34, 3 February 2016
Line 1:		Line 1:
	[[Category:Done ~~2015~~-09-05]]		[[Category:Done 2016-01-15]]
	[[category: units]]		[[category: units]]
	<onlyinclude>The '''candela''' (cd) is the [[SI]] [[units\|unit]] of [[luminous intensity]], which is ~~essentially~~ a measure of [[power]] emitted from a source.</onlyinclude> The definition for a candela is:<ref name=web1>NIST. ''Base unit definitions: Candela'' [Online] Available: http://physics.nist.gov/cuu/Units/candela.html </ref>		<onlyinclude>The '''candela''' (cd) is the [[SI]] [[units\|unit]] of [[luminous intensity]], which is a measure of [[power]] emitted from a light source.</onlyinclude> The definition for a candela is:<ref name=web1>NIST. ''Base unit definitions: Candela'' [Online] Available: http://physics.nist.gov/cuu/Units/candela.html </ref>

	The luminous intensity, in a given direction, of a source that emits monochromatic [[radiation]] of [[frequency]] 540 x 10<sup>12</sup> [[hertz]] and that has a radiant intensity in that direction of 1/683 [[watt]] per steradian.		The luminous intensity, in a given direction, of a source that emits monochromatic [[radiation]] of [[frequency]] 540 x 10<sup>12</sup> [[hertz]] and that has a radiant intensity in that direction of 1/683 [[watt]] per steradian.

J.williams: 1 revision imported

2015-09-03T18:22:28Z

1 revision imported

← Older revision	Revision as of 18:22, 3 September 2015
(No difference)

Jmdonev at 18:55, 28 August 2015

2015-08-28T18:55:17Z

← Older revision		Revision as of 18:55, 28 August 2015
Line 1:		Line 1:
	[[Category:Done 2015-02-15]]		[[Category:Done 2015-09-05]]
	[[category: units]]		[[category: units]]
	<onlyinclude>The '''candela''' (cd) is the [[SI]] unit of luminous intensity, which is essentially a measure of [[power]] emitted from a source.</onlyinclude> The definition for a candela is:<ref name=web1>NIST. ''Base unit definitions: Candela'' [Online] Available: http://physics.nist.gov/cuu/Units/candela.html </ref>		<onlyinclude>The '''candela''' (cd) is the [[SI]] [[units\|unit]] of [[luminous intensity]], which is essentially a measure of [[power]] emitted from a source.</onlyinclude> The definition for a candela is:<ref name=web1>NIST. ''Base unit definitions: Candela'' [Online] Available: http://physics.nist.gov/cuu/Units/candela.html </ref>

	The luminous intensity, in a given direction, of a source that emits monochromatic [[radiation]] of [[frequency]] 540 x 10<sup>12</sup> [[hertz]] and that has a radiant intensity in that direction of 1/683 [[watt]] per steradian.		The luminous intensity, in a given direction, of a source that emits monochromatic [[radiation]] of [[frequency]] 540 x 10<sup>12</sup> [[hertz]] and that has a radiant intensity in that direction of 1/683 [[watt]] per steradian.

J.williams: 1 revision imported

2015-08-26T21:30:53Z

1 revision imported

← Older revision	Revision as of 21:30, 26 August 2015
(No difference)

J.williams at 16:51, 12 August 2015

2015-08-12T16:51:37Z

New page

[[Category:Done 2015-02-15]]
[[category: units]]
<onlyinclude>The '''candela''' (cd) is the [[SI]] unit of luminous intensity, which is essentially a measure of [[power]] emitted from a source.</onlyinclude> The definition for a candela is:<ref name=web1>NIST. ''Base unit definitions: Candela'' [Online] Available: http://physics.nist.gov/cuu/Units/candela.html </ref>

The luminous intensity, in a given direction, of a source that emits monochromatic [[radiation]] of [[frequency]] 540 x 10<sup>12</sup> [[hertz]] and that has a radiant intensity in that direction of 1/683 [[watt]] per steradian.

Candela is Latin for the word 'candle', and a typical candle's luminous intensity is actually about equal to one candela.<ref>SI Units Explained. ''Luminous Intensity'' [Online] Available: http://www.si-units-explained.info/luminosity/</ref>

Visit Dr. Rowlett's [http://www.unc.edu/~rowlett/units/dictC.html#candela unit dictionary] to learn more about the candela, and learn more about luminous intensity [http://www.si-units-explained.info/luminosity/ here].

==References==
{{reflist}}
[[Category:Uploaded]]