Notes for 11-10-97

The speed of light in a vacuum is 3x10^18 Angstroms/sec. An Angstrom is 10^-10 meters.

Light (electromagnetic spectrum) varies in:

1. wavelength (this determines the 'color') (Y)
   • The longer the wavelength the lower the energy
   • IR/Red is 7700 angstroms
   • Violet/UV is 3900 angstroms
   • The wavelength is in part determined by the material the light is passing through
2. frequency (f)
   • = wavelength/time
   • frequency stays the same irregardless of changes due to passing through different media
3. energy (e)
   • Plank's law: e = hf = hc/Y
     • h = Plank's constant
4. speed 'c'
   • This is variable, depending on the medium the light is traveling through.
   • For practical (ie our) purposes, the speed of light in air is the same as that in a vacuum.
     • This results in bending as light goes from one medium to another:
       • Refractive Index; proportional to speed of light in a material (n)
       • c/c(m) = n = (speed of light in air)/(speed of light in material)
       • n has a reciprocal relationship to speed; as speed goes down n goes up
         • garnet n = 1.85
         • quartz n = 1.54
         • balsam = 1.537
   • c = Y*f

Monochromatic is light that is all the same wavelength.

Polychromatic is light that is white (ie has a mix of wavelengths)

The vibration direction of light is at right angles to the propagation direction.

{done through 11-10p2 start}

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