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  2. Light - Wikipedia

    en.wikipedia.org/wiki/Light

    Light, visible light, or visible radiation is electromagnetic radiation that can be perceived by the human eye. [1] Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terahertz .

  3. List of unsolved problems in chemistry - Wikipedia

    en.wikipedia.org/wiki/List_of_unsolved_problems...

    How do the spin–orbit coupling, other relativistic corrections, and inter-electron effects modify the chemistry of the trans-actinides? [1] [2] Is it possible to create a practically-useful lithium–air battery? [3]

  4. Luminous intensity - Wikipedia

    en.wikipedia.org/wiki/Luminous_intensity

    Light with the same radiant intensity at other wavelengths has a lower luminous intensity. The curve which represents the response of the human eye to light is a defined standard function y (λ) or V (λ) established by the International Commission on Illumination (CIE, for Commission Internationale de l'Éclairage ) and standardized in ...

  5. Balmer series - Wikipedia

    en.wikipedia.org/wiki/Balmer_series

    where λ is the wavelength of the absorbed/emitted light and R H is the Rydberg constant for hydrogen. The Rydberg constant is seen to be equal to ⁠ 4 / B ⁠ in Balmer's formula, and this value, for an infinitely heavy nucleus, is ⁠ 4 / 3.645 0682 × 10 −7 m ⁠ = 10 973 731.57 m −1. [3]

  6. Refractive index - Wikipedia

    en.wikipedia.org/wiki/Refractive_index

    [1]: 236 The birefringence of the material is the difference between these indices of refraction, Δn = n e − n o. [1]: 237 Light propagating in the direction of the optical axis will not be affected by the birefringence since the refractive index will be n o independent of polarization. For other propagation directions the light will split ...

  7. Dispersion (optics) - Wikipedia

    en.wikipedia.org/wiki/Dispersion_(optics)

    In a dispersive prism, material dispersion (a wavelength-dependent refractive index) causes different colors to refract at different angles, splitting white light into a spectrum. A compact fluorescent lamp seen through an Amici prism. Dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency. [1]

  8. Photochemistry - Wikipedia

    en.wikipedia.org/wiki/Photochemistry

    Photochemical immersion well reactor (50 mL) with a mercury-vapor lamp.. Photochemistry is the branch of chemistry concerned with the chemical effects of light. Generally, this term is used to describe a chemical reaction caused by absorption of ultraviolet (wavelength from 100 to 400 nm), visible (400–750 nm), or infrared radiation (750–2500 nm).

  9. Lumen (unit) - Wikipedia

    en.wikipedia.org/wiki/Lumen_(unit)

    In equation form, 1 lx = 1 lm/m 2. A source radiating a power of one watt of light in the color for which the eye is most efficient (a wavelength of 555 nm, in the green region of the optical spectrum) has luminous flux of 683 lumens. So a lumen represents at least 1/683 watts of visible light power, depending on the spectral distribution.