Phot

Short description: Measure of illuminance

For the 9th-century theologian and scholar, see Patriarch Photius I of Constantinople.

Phot

Unit system| CGS units
Unit of| Illuminance
Symbol| ph
Conversions
1 ph in ...| ... is equal to ...
SI derived unit|  10000 lx
SAE units|  929 fc

A phot (ph) is a photometric unit of illuminance, or luminous flux through an area. It is not an SI unit but rather is associated with the older centimetre–gram–second system of units. The name was coined by André Blondel in 1921.[1]

Metric equivalence:

1 phot=1 lumencentimetre2=10,000 lumensmetre2=10,000 lux=10 kilolux

Metric dimensions:

Illuminance = luminous intensity × solid angle / length2

## See also

* Illuminance
* Lumen (unit)
* Lux
* Photometry (optics)
* Light

## References

1. ↑ Parry Moon. "System of photometer concepts", in the Journal of the Optical Society of America, volume 32, number 6 (June 1942), doi:10.1364/JOSA.32.000348. – Page 355: "The lumen was proposed by Blondel in 1894 and is now universally accepted. The names, phot and stilb were likewise coined by Blondel (1921) and are in general use on the Continent."

## External links

* Knowledgedoor, LLC (2005). Library of Units and Constants: Illuminance Quantity. Retrieved 2006-07-21.
* Illuminance Converter. Retrieved 2006-07-21.

* v
* t
* e

CGS units

Base units|

centimetre • gram • second

Derived non EM units|

barye • dyne • erg • gal • kelvin • poise • phot • stilb

Derived EMU units|

abcoulomb • abhenry • abohm • biot • gauss • gilbert • maxwell • oersted

Derived ESU units|

statcoulomb • statvolt

0.00

(0 votes)

Original source: https://en.wikipedia.org/wiki/Phot. Read more

|

Retrieved from "https://handwiki.org/wiki/index.php?title=Physics:Phot&oldid=422110"
*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template