Reflection

1
Reflection Refraction
2
Nature of Light

• Wave like properties
• Reflection
• Refraction
• Diffraction
• Particle like properties
• Photoelectric Effect
• Ultraviolet Catastrophy

3
Speed of Light

• Roemers Method - Determined from the eclipse of
  Io.
• Fizeaus Method - Measured by the round trip from
  a mirror.

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4
Ray Optics

• Waves move in a straight line in the direction of
  the rays.
• Diffraction - Bending of light through a small
  opening.
• At a small opening, assume each opening acts as a
  source of spherical waves.

d - opening width
5
Reflection

• Change in direction of a wave due to striking a
  surface.
• Specular - Light rays leave a smooth surface in
  an orderly fashion.
• Diffuse - Light rays randomly leave a rough
  surface.

6
Reflection

• Law of Reflection - The angle of reflection
  equals the angle of incidence.

7
Refraction

• Change in the path of light due to a change in
  its speed.
• When light slows down, the angle becomes smaller.

8
Inferior Mirages

• Hot air at the surface refracts light upward
  giving a second image of a distant object.

9
Prism

• At what angle does light leave an equilateral
  prism is the incident light is parallel with the
  base?

10
Dispersion

• Different frequencies of light take different
  paths after refraction because the index of
  refraction is dependent on wavelength.
• Smaller wavelengths experience a larger index of
  refraction.

11
Rainbows

• Sunlight refracts when entering a droplet,
  reflects off the back and refracts when leaving
  the front.

Why does a rainbow have red at the top?
12
Halos

• Shorter wavelengths of light travel slower
  through ice and, therefore, refract more than red
  light.

Going from less dense to more dense material
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13
HaloSim Ice Columns

• 22 Halo
• Sun dog
• Sun Pillar
• Upper tangent arc

14
Double Halo
15
Critical Angle

• Critical Angle - Angle of incidence corresponding
  to a 90 angle of refraction.
• At this angle and beyond you get total internal
  reflection.
• What is the critical angle between water and air?

n2
n1
16
Brewster Angle

• Light reflecting off a surface is partially
  polarized.
• At the Brewster Angle the light is entirely
  polarized.

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n1
n2
17
Scattering of Light

• Spectrum of light
• White Clouds
• Blue Skies
• Red Sunsets