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  2. Visible spectrum - Wikipedia

    en.wikipedia.org/wiki/Visible_spectrum

    Visible-light spectroscopy is an important tool in astronomy (as is spectroscopy at other wavelengths), where scientists use it to analyze the properties of distant objects. Chemical elements and small molecules can be detected in astronomical objects by observing emission lines and absorption lines.

  3. BBC Bitesize - Wikipedia

    en.wikipedia.org/wiki/BBC_Bitesize

    GCSE Bitesize was launched in January 1998, covering seven subjects. For each subject, a one- or two-hour long TV programme would be broadcast overnight in the BBC Learning Zone block, and supporting material was available in books and on the BBC website. At the time, only around 9% of UK households had access to the internet at home.

  4. Visible-light astronomy - Wikipedia

    en.wikipedia.org/wiki/Visible-light_astronomy

    Visible-light astronomy has existed as long as people have been looking up at the night sky, although it has since improved in its observational capabilities since the invention of the telescope, which is commonly credited to Hans Lippershey, a German-Dutch spectacle-maker, [1] although Galileo played a large role in the development and ...

  5. Spectroscopy - Wikipedia

    en.wikipedia.org/wiki/Spectroscopy

    An example of spectroscopy: a prism analyses white light by dispersing it into its component colors. Spectroscopy is the field of study that measures and interprets electromagnetic spectrum. [1] [2] In narrower contexts, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum.

  6. Photochromism - Wikipedia

    en.wikipedia.org/wiki/Photochromism

    Photochromism is the reversible change of color upon exposure to light. It is a transformation of a chemical species ( photoswitch ) between two forms by the absorption of electromagnetic radiation ( photoisomerization ), where the two forms have different absorption spectra.

  7. Opacity - Wikipedia

    en.wikipedia.org/wiki/Opacity

    Opacity is the measure of impenetrability to electromagnetic or other kinds of radiation, especially visible light. In radiative transfer , it describes the absorption and scattering of radiation in a medium , such as a plasma , dielectric , shielding material , glass, etc.

  8. 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 .

  9. Luminous efficacy - Wikipedia

    en.wikipedia.org/wiki/Luminous_efficacy

    Not all wavelengths of light are equally visible, or equally effective at stimulating human vision, due to the spectral sensitivity of the human eye; radiation in the infrared and ultraviolet parts of the spectrum is useless for illumination. The luminous efficacy of a source is the product of how well it converts energy to electromagnetic ...