Unformatted text preview: e at
UCSD in 2000 by Shelly Schultz and David Smith (my
friend, and former college roommate here at UCSD).
Tuesday, November 12, 2013 Light wave with index n
Traveling wave with frequency ω = 2π /T
vacuum index n k = | | = 2π /λ
k with ω = ωvac
k = nkvac λ = λvac /n Same time dependence on two sides,
only the spatial part is affected. Tuesday, November 12, 2013 wavelength, index n
λ = λvac /n leads to
Snell’s law Tuesday, November 12, 2013 Fermat’s principle
“Light always takes the path of shortest time.”
If n is unchanged everywhere, the shortest time path is
the same as the shortest distance path. Even if light
goes faster in some regions than others (n is larger in
the slower regions), light always manages to ﬁnd and
take the quickest path. Example: mirages Tuesday, November 12, 2013 Reﬂection & refraction Fermat: the path always (locally) minimizes the time
needed for light to go from source to observer.
Shortens distance on slower side, to reduce time.
n1 sin θ1 = n2 sin θ2 Tuesday, November 12,...
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