This preview shows page 1. Sign up to view the full content.
Unformatted text preview: 2013 “Snell’s law” Refraction, cont.
n1 sin θ1 = n2 sin θ2 !
sin θ1 =
sin θ2 ≤ 1
image No refraction
if this is >1!
sin θ2 = n1 /n2 Total internal reﬂection inside slower region if the angle is
big enough. Try it out in a pool. From underwater, look up,
out of the water: see a mirrored surface at big angles.
Tuesday, November 12, 2013 “Where is
that ﬁsh?” Fiber optics
Total internal reﬂection. Basis for global, landline
data transfer. Tuesday, November 12, 2013 Dispersion
If n = n( ω ) or, equivalently, n = n( λ) Shorter wavelengths have bigger index of refraction
(can picture that they collide into more atoms, so
they are slowed more than longer wavelenghts).
So shorter wavelengths are bent more by the prism.
Tuesday, November 12, 2013 Polarization
E.g.: E = E0 y cos(kx − ω t) Polarized light wave.
Most light sources (light bulbs, sun, etc) make
unpolarized light, which is a superposition of
randomly polarized light waves. Polarizing ﬁlters
block the components except those with E along
(actually perpendicular to) the polarizer’s axis. Tuesday, November...
View Full Document