Diffraction

1
Refraction
n1 1
?1
?1
?1
?2
n2 gt 1
?2
?2
Radius vT (c/n)T
2
Triangle hcg sin ?2 ?2/hc
Triangle hce sin ?1 ?1/hc
sin ?1 /sin ?2 ?1 /?2 (v1/f) / (v2/f) v1/v2
(c/n1)/(c/n2) n2/n1
n1 sin ?1 n2 sin ?2
Snells Law
3
n1 sin ?1 n2 sin ?2
?2?/2 gt sin ?c n2/n1
Water n1.5 Air n1.
?c 41.80
Reflection refraction
4
Halo
5
Sun Dogs
n sin?2sin ?1
n sin?3sin ?4
?2 ?3 600
Deflection ?1 ?4 - 600
n1.33
6
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7
nred lt nblue
vredc/nred gt vblue c/nblue
prism
8
Fermats Principle

• The path taken by light in travelling from one
  point to another is such that the time of travel
  is a minimum

9
Refraction

• Minimize t with respect to x
• dt/dx0 using dL1/dxx/L1 sin?1 and
  dL2/dx(x-d)/L2 -sin?2
• dt/dx(n1sin ?1 - n2 sin ?2)/c 0

Time?
10
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