2 The Wave Nature of Light

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2- The Wave Nature of Light
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Beginnings Greek Arab scientists
Johannes Kepler (1571-1630) Human
Eye Spectacles Telescope Camera Obscura
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Thomas Young Mixing Red, Green, Blue - we see
White James Clerk Maxwell - other colors can be
produced from RGB Hermann von Helmholtz - eye has
3 color sesnsors, each having its own color peak
and spread of colors
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Isaac Newton
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White light is a collection (summation) of colors
that a prism separates
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ALSO 2 separated colors, when recombined,
could yield a third different color! ? What we
call color is not just a physical property of the
light, but is related to how we perceive it
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1802 Thomas Young - Diffraction Interference
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Light is a Wave!
Wavelength ? - Units meters (m) Amplitude A -
but INTENSITY that is detected actually goes as
A2 Frequency ? or f - Unit cycles/s, universally
called Hertz (1 Hertz 1 cycle/s) Speed - Units
m/s NOTE v f ?
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Maxwell - Light is a electromagnetic wave with f
? c c speed of light in a vacuum In other
media, vc/n nindex of refraction Vacuum
n1.00000 Air n1.000 Water n1.3 n depends on
?, giving rise to dispersion
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Heinrich Hertz - produces detects radio
waves William Herschel discovers infrared light
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Polarization
Total plane polarization Unpolarized Partially
polarized
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• 4 methods
• Transmission
• Reflection
• Refraction
• Scattering

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Transmission
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J/K is the cosine of the angle between the two,
so J K cos (angle JK). For a 45? angle, we get
See Java Applets
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Reflection
Brewsters Angle
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Refraction
birefringence
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Many plastic materials become birefringent when
physically stressed - much more later on
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Scattering
Hadingers Brush
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Optical Activity
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Polarized Light in the Environment
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