However, photometric units are precisely defined and precisely measurable.
2.
The lumen is the photometric unit of light output.
3.
A comparison of the watt and the lumen illustrates the distinction between radiometric and photometric units.
4.
Because lumens are photometric units, their relationship to watts depends on the wavelength according to how visible the wavelength is.
5.
"' Andr?Eug�ne Blondel "'( 28 August 1863 15 November 1938 ) was a photometric units of measurement.
6.
Candlepower, a photometric unit defined in the United Kingdom Act of Parliament Metropolitan Gas Act 1860 and adopted at the International Electrotechnical Conference of 1883, was based the light produced by a pure spermaceti candle.
7.
The photometric unit "'lumerg "', also proposed by the Committee on Colorimetry in 1937, correlates with the old CGS unit erg in the same way that the lumen second correlates with the radiometric unit joule, so that 10 7 lumerg = 1 lm?" s.
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