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Candela

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This article is about the unit of luminous intensity. For other uses, see Candela (disambiguation). Candela Photopic (black) and scotopic [1] (green) luminosity functions. The photopic includes the CIE 1931 standard [2] (solid), the Judd–Vos 1978 modified data [3] (dashed), and the Sharpe, Stockman, Jagla & Jägle 2005 data [4] (dotted). The horizontal axis is wavelength in nm. Unit information Unit system SI base unit Unit of Luminous intensity Symbol cd  Unit conversions 1 cd in ... ... is equal to ...     international candles     0.981 cp     Hefner Kerze     1.11 HK The candela ( / k æ n ˈ d ɛ l ə / or / k æ n ˈ d iː l ə / ; symbol: cd) is the base unit of luminous intensity in the International System of Units (SI); that is, luminous power per unit solid angle emitted by a point light source in a particular direction. Luminous intensity is analogous to radiant intensity, but instead of simply adding up the cont

Lumen (unit)

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For other uses, see Lumen (disambiguation). Lumen Unit system SI derived unit Unit of Luminous flux Symbol lm  Unit conversions 1 lm in ... ... is equal to ...     SI base units     1 lm = 1 cd ⋅ sr. The lumen (symbol: lm) is the SI derived unit of luminous flux, a measure of the total quantity of visible light emitted by a source. Luminous flux differs from power ( radiant flux ) in that radiant flux includes all electromagnetic waves emitted, while luminous flux is weighted according to a model (a "luminosity function") of the human eye's sensitivity to various wavelengths. Lumens are related to lux in that one lux is one lumen per square meter. The lumen is defined in relation to the candela as 1 lm = 1 cd ⋅ sr. A full sphere has a solid angle of 4π steradians, [1] so a light source that uniformly radiates one candela in all directions has a total luminous flux of 1 cd × 4π sr = 4π cd⋅sr ≈ 12.57 lumens . [2] Conten

Human eye

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This article is about the human eye. For eyes in general, see Eye. This article uses anatomical terminology; for an overview, see Anatomical terminology. The human eye 1. vitreous body 2. ora serrata 3. ciliary muscle 4. ciliary zonules 5. Schlemm's canal 6. pupil 7. anterior chamber 8. cornea 9. iris 10. lens cortex 11. lens nucleus 12. ciliary process 13. conjunctiva 14. inferior oblique muscle 15. inferior rectus muscle 16. medial rectus muscle 17. retinal arteries and veins 18. optic disc 19. dura mater 20. central retinal artery 21. central retinal vein 22. optic nerve 23. vorticose vein 24. bulbar sheath 25. macula 26. fovea 27. sclera 28. choroid 29. superior rectus muscle 30. retina Details Identifiers Latin Oculi Hominum Greek ἀνθρώπινος ὀφθαλμός MeSH D005123 TA A01.1.00.007 A15.2.00.001 FMA 54448 Anatomical terminology [edit on Wikidata] The human eye is an organ which reacts to light and pressure. As a sense organ, the mamm