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3.6: Key Terms

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    Stars and Light Key Terms

    • radiation: emission of energy as electromagnetic waves or photons, also the transmitted energy itself
    • electromagnetic radiation: radiation consisting of waves propagated through regularly varying electric and magnetic fields and traveling at the speed of light
    • wavelength: the distance from crest to crest or trough to trough in a wave
    • frequency: the number of waves that cross a given point per unit time
    • inverse square law: for light the amount of energy flowing through a given area in a given time decreases in proportion to the square of the distance from the source of energy or light
    • luminosity: the rate at which a star or other object emits electromagnetic energy into space; the total power output of an object
    • apparent brightness: a measure of the amount of light received by Earth from a star or other object—that is, how bright an object appears in the sky, as contrasted with its luminosity
    • electromagnetic spectrum: the full range of electromagnetic waves, from radio to gamma rays
    • infrared: electromagnetic radiation of wavelength 103–106 nanometers; longer than the longest red wavelengths that can be perceived by the eye, but shorter than radio wavelengths
    • visible light: electromagnetic radiation with wavelengths of roughly 400–700 nanometers; visible to the human eye
    • ultraviolet: electromagnetic radiation of wavelengths 10 to 400 nanometers; shorter than the shortest visible wavelengths
    • X-rays: electromagnetic radiation with wavelengths between 0.01 nanometer and 10 nanometers; intermediate between those of ultraviolet radiation and gamma rays
    • gamma rays: photons of electromagnetic radiation of energy with wavelengths no longer than 0.01 nanometer; the most energetic form of electromagnetic radiation
    • Wien's law: formula that relates the temperature of a blackbody to the wavelength at which it emits the greatest intensity of radiation
    • blackbody: an idealized object that absorbs all electromagnetic energy that falls onto it

    3.6: Key Terms is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by LibreTexts.

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