OUTLINE
1. Polarization (continued)
2. Reflection and refraction of light (Skip
Section 33-10 on polarization by reflection
and Brewster’s law.)
3. Plain mirrors
CHECKPOINT 4
Four pairs of polarizing sheets are placed in the
path of initially unpolarized light, with the polarizing
direction of each sheet indicated by the dashed line.
Which pair lets the largest fraction of light through?
Which pair lets through the least?
QUIZ
45°
45°
(a)
(b)
• Initially unpolarized light is sent into a set of three
polarizing sheets, either a or b. Which set lets more
light through?
a. (b completely blocks light.)
• What fraction of the light’s initial intensity is
transmitted?
1/8
CHECKPOINT
(a)
(b)
Light travels from a medium with an index of
refraction n1 into a medium with an index of
refraction n2. In case a, is n2 larger or smaller than
n1?
n2 > n1.
Chromatic dispersion
White light
violet
red
Prisms have double reflections and a limited resolution. To
study a light spectrum, diffraction gratings (see Chapter 36)
are used instead of prisms. See a demo in the lobby.
Total internal reflection
n2
n1
For a total reflection to occur,
n1 has to be larger than n2.
Quiz
radius
n2 ≈ 1
n1 = 1.33
A point source of light is located 3 m below the body
of water. Find the diameter of the circle at the
surface through which light emerges from the water.
θ = 48.8° 2r = 6.84 m
Plain mirrors
i = –p
All reflected rays
extrapolate to point I, as
if they all originated
there. The viewer
perceives a virtual
image located at I.
Quiz
h
A six-foot-tall gator stands in front of a mirror. In
order for him to see himself from top to toe in the
mirror, what is the minimum height required of the
mirror?
3 ft.
CHECKPOINT 1
• A person stands between two vertical, parallel
mirrors A and B separated by distance d and looks
into mirror A. How deep behind mirror A is the first,
closest image of object O?
0.2d.
• How deep behind mirror A is the second image?
1.8d.
• How about the third image?
2.2d.