Law 1 when a dense substance solid liquid or

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Law #1:  When a dense substance (solid, liquid, or compressed gas) is heated up,  it produces light (it begins to glow).  Passing that light through a prism produces a “smooth rainbow of colors” that we call a  continuous spectrum. Law #2:  When a low-density gas is energized, it begins to glow. When this light  is passed through a prism, the spectrum looks like a series of bright lines with  different colors.  This is called an  emission line spectrum. Law #3:  When the light produced by a hot, dense substance passes through a cool gas before passing through a prism, the spectrum looks like a  continuous   spectrum with a series of dark lines in it.  This is called an  absorption line  spectrum.   Interestingly, the locations of the dark lines produced by the cool gas  are in  exactly  the same place as the bright lines produced when that gas is heated  up. L IGHT  D ESCRIBED   AS   A  W AVE In 1873, a Scottish physicist named James Clerk Maxwell developed a theory that  describes light as an electromagnetic wave (the  electromagnetic  is not so important for  us, but the  wave  is…).  We will make use of some of the basic elements of this  description of light: The speed of the wave is equal to the speed of light The size of the wave is characterized by the distance between two successive  crests (or peaks).  This is called the  wavelength.   The symbol used for  wavelength is the Greek letter lambda:  λ . QUESTION:  When viewed on a typical computer screen or tablet, what is the 
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3 wavelength (approximate) for the wave shown on the above diagram? About 1/10 meter (decimeter, or 10 centimeters) In terms of how we see light, each color has its own characteristic wavelength.  The table  below summarizes the colors of the spectrum and their corresponding wavelengths. An ANGSTROM is an insanely small unit of measurement. 10 BILLION of them can fit  into a single meter.  Visible Colors & Corresponding Wavelengths Color Wavelength Range (Angstroms) Red 7800 – 6200 Orange 6200 – 6000 Yellow 6000 – 5750 Green 5750 – 4900 Blue 4900 – 4500 Violet 4500 - 3900 Visible light, however, is just a tiny sliver of the entire “electromagnetic spectrum,”  which contains all the different wavelengths of light:
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4 W ARM -U P  Q UESTIONS These questions will require you to use a combination of lecture slides and Google  searches. A good basic description for most of the material can be found here: 1. What color of visible light
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  • Spring '16
  • Nelson,D.
  • Light, spectrum

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