Refraction and Snell's Law

1
A fish swims below the surface of the water at
point P. An observer at point O sees the fish at
1) a greater depth than it really is 2) the
same depth 3) a shallower depth than it really is
2
A fish swims below the surface of the water at
point P. An observer at point O sees the fish at
1) a greater depth than it really is 2) the
same depth 3) a shallower depth than it really is
3
A fish swims below the surface of the water.
Suppose an observer is looking at the fish from
point O?, which is directly above the fish. The
observer sees the fish at
1) a greater depth than it really is 2) the
same depth 3) a shallower depth than it really is
4
A fish swims below the surface of the water.
Suppose an observer is looking at the fish from
point O?, which is directly above the fish. The
observer sees the fish at
1) a greater depth than it really is 2) the
same depth 3) a shallower depth than it really is
5
To shoot a fish with a gun, should you aim
directly at the image that you see, slightly
above the image, or slightly below it? 1) aim
directly at the image 2) aim slightly above 3)
aim slightly below
6
To shoot a fish with a gun, should you aim
directly at the image slightly above or slightly
below? 1) aim directly at the image 2) aim
slightly above 3) aim slightly below
You will see the fish at a position above its
actual position, so you should aim below this
image.
7
To shoot a fish with a laser pistol, should you
aim directly at the image slightly above or
slightly below? A) aim directly at the
image B) aim slightly above C) aim slightly
below, about where you would aim a gun D) aim
even further below than you would aim with a gun
8
light from fish
laser beam
To shoot a fish with a laser pistol, should you
aim directly at the image slightly above or
slightly below? A) aim directly at the
image B) aim slightly above C) aim slightly
below, about where you would aim a gun D) aim
even further below than you would aim with a gun
The light from the laser beam will also bend when
it hits the air-water interface, so aim directly
the fish.
9
An observer views two closely spaced lines
through an angled piece of glass. To the
observer, the lines appear
1) shifted to the right 2) shifted to the
left 3) spaced farther apart 4) spaced closer
together 5) no change -- exactly as before
10
?1
v1?t
v2?t
?2
11
?1
v1?t
?i
?i
h
?r
?2
v2?t
?r
12
Snells Law
We can classify materials by their index of
refraction defined as the ratio of
speed of light in a vacuum, c speed of light
through medium, v
i.e.
Note then that
reversing the indices!
So often Snells Law is also written as n1sin?1
n2sin?2
13
A ray of light is shown entering a glass prism,
bending down (toward the normal) as it enters.
As the ray re-enters the air through the opposite
face of the prism

1. it bends up.
2. it passes through without bending.
3. it bends further down.

14
A ray of light is shown entering a glass prism,
bending down (toward the normal) as it enters.
Glass-into-air light bends away from normal
Air-into-glass light bends toward normal
As the ray re-enters the air through the opposite
face of the prism

1. it bends up.
2. it passes through without bending.
3. it bends further down.