light: geometric optics
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Light: Geometric Optics. Introduction – 23-1, 23-4, 23-5, 24-10. Light. Electromagnetic Spectrum. Light. Light is the Part of the EM spectrum that stimulates the retina of the human eye ROY G BIV. Ray Model of Light. Light travels in straight line in vacuum or uniform media - PowerPoint PPT PresentationTRANSCRIPT
Light: Geometric Optics
Introduction – 23-1, 23-4, 23-5, 24-10
Light Electromagnetic Spectrum
Light Light is the Part of the EM spectrum
that stimulates the retina of the human eye
ROY G BIV
Ray Model of Light Light travels in straight line in
vacuum or uniform media Ray model assumes straight line
travel for light Ray Optics – ray diagrams to study
travel of light; ignores wave nature of light
Speed of Light Before 1700, thought to be
instantaneous Galileo worked on speed of light
Couldn’t believe that it was that fast! Ole Roemer – first to determine light
traveled with measureable speed A.A. Michelson – measured light
between two mountaintops in California2.997996 x 108 +/- .00004 x 108 m/s
1960’s Lasers found to measure speed of light better than atomic clocks v = λf = c
Sources of Light luminous--body emits light illuminated--body reflects light incandescent--glows HOT; luminous;
W wire is heated by electricity and glows inside a light bulb
luminous flux, P--rate at which light is emitted from a sourceLumen – lm – unit of flux
illuminance, E--lm/m2 or lux, lx
Illumination 100W light bulb – 1750 lm
If 1m sphere: 1750 lm / (4π(1)2) = 1750/4π lx
If 2m sphere: 1750 lm / (4π(2)2) = 1750/16π lx
Candela cd – measures luminous intensity1750/4π lx = 139 cd
Illumination To increase illumination
increase flux of alternate sourcedecrease distance between source and
surface
Illuminance = E = P/4πd2
perpendicular line between source and surface
point sources
Light and Matter Transparent – light through;
transmitted Translucent — light sort of through;
transmits and diffuses light Opaque – light not through; absorbs
reflects all light; no transmission
Color Models
Additive - RGB Subtractive CMY
Polarizers
Dual Polarizers