10 Optics Part 1

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10 - Optics Part 1
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Preliminaries
Reflection (Hero(n) of Alexandria ) ?1?1
Only determines direction of reflection, not SPD
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Refraction
v speed of light in mediun (material) c speed
of light in vacuum v c/n n index of
refraction of medium
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Trigonometry refresher Given the right triangle
shown here sin(B) b/c cos(B) a/c tan(B)
b/a
Snells Law of Refraction n1 sin ?1 n2 sin ?2
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Characteristic Frequencies
Electric charges in matter respond to a driving
force of the electromagnetic wave. Greatest
response at some favored or resonant frequency
?0
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Selective Absorption
Damping force diminishes oscillations - Damped
oscillations
(hard to illustrate without demonstration movies
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Dispersion
Light of different wavelengths will be refracted
by different angles Amount of refraction depends
on the nature of the material normal dispersion -
more refraction at higher frequencies (shorter
wavelengths) anomalous dispersion - more
refraction at lower frequencies (longer
wavelengths)
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(a) the amplitude and phase of a damped driven
oscillator
(c) n index of refraction k the
absorption coefficient
(b) dielectric functions
(d) also determines reflectance, too!