Wave Nature of Light

Question 1

Snell’s Law

Answer 1

n[1]sinΘ[1] = n[2]sinΘ[2]
*n = c/v*

Question 2

Critical Angle

Answer 2

Snell’s law leads to angle of refraction of 90°

Question 3

Total Internal Reflection

Answer 3

When the angle of incidence is greater than the critical angle. Applications: optical instruments (binoculars), fiber optics, diamonds and gems

Question 4

Corpuscular Theory (Newton)

Answer 4

Light travelling at normal speeds follows a curved path, therefore light travels high speeds.
Collisions between light particles at edges of ‘slit’ create diffraction.
Reflection follows laws of motion (perfectly elastic collisions).
Particles bend if v increases.
Theory of fits for partial reflect/refraction
Dispersion is based on mass (different mass different refraction)

Question 5

Wave Theory (Huygens)

Answer 5

Rays represent direction of motion of a wave front.
Diffraction…
Waves obey laws of reflection from optics (Θi = Θr) for plane/curved surface.
Light Bends toward the normal b/c v is slower in optically denser medium.
Waves partially reflect/refract whenever there is change in v, which varies w/Θi
Dispersion occurs b/c different wavelengths

Question 6

Polarization of Light Waves

Answer 6

Light waves oscillate perpendicular to the direction of travel.

Question 7

Interference of Thin Films (free end)

Answer 7

Destructive Interference - t &laquo_space;λ, t = 1/2 λ, t = λ…

Constructive Interference - t = 1/4 λ, t = 3/4 λ, t = 5/4 λ…

Question 8

Interference of Thin Films (fixed end)

Answer 8

Destructive Interference - t = 1/4 λ, t = 3/4 λ, t = 5/4 λ…
Constructive Interference - t &laquo_space;λ, t = 1/2 λ, t = λ…

Question 9

Slit measurements

Answer 9

Single slit - Δy
Double slit - Δx (nodes)
Diffraction Gratings - maximums