Physics 212 Lecture 27, Slide 1

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Physics 212 Lecture 27
Optical Devices
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Music

• Who is the Artist?
• Jefferson Airplane
• Grateful Dead
• Moby Grape
• The Doors
• Cream

What a Long Strange Trip
Its Been There is (or was) nothing like a Dead
concert ! Need I say anything more ?
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Engineers Without BordersFundraiser
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Cause he gets up in the morning, and he goes to
work at nine, And he comes back home at
five-thirty, gets the same train every
time. Cause his world is built on punctuality, it
never fails. CHORUS And he's oh, so good, and
he's oh, so fine, And he's oh, so healthy, in his
body and his mind. He's a well respected man
about town, doing the best things so
conservatively. And his mother goes to meetings,
while his father pulls the maid, And she stirs
the tea with councilors, while discussing foreign
trade, And she passes looks, as well as bills, at
every suave young man CHORUS And he likes his
own backyard, and he likes his fags the
best, Cause he's better than the rest, and his
own sweat smells the best, And he hopes to grab
his father's loot, when Pater passes
on. CHORUS And he plays at stocks and shares,
and he goes to a Regatta, He adores the girl next
door, and he's dying to get at her, But his
mother knows the best about the matrimonial
stakes. CHORUS
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Your thoughts
There are so many formulas and derivations, what
do we really have to know?
angular magnification, two lens systems with the
second inside the focal length. yay last
lecture! i'll write my haiku now two twelve is
over no more gauss or e and m just one more
week left
Material seems easy, but its really hard to keep
track of what's going on. Like when its virtual,
real, focal point...I get lost easily.
For next year the students should have their
choice of prelecture voicing, like Microsoft Sam,
Vanilla Ice, or Mr. T. ("I pity tha fool who
don't know that far-sighted people need
converging-lens glasses.") Aaand how!
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Executive Summary - Lenses
real inverted bigger
2f S f
virtual upright bigger
f S 0
virtual upright smaller
S 0
diverging
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Executive Summary - Mirrors
real inverted bigger
2f S f
concave
f
virtual upright bigger
f S 0
virtual upright smaller
S 0
convex
f
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Note Drawing principal rays for more than one
element is tricky, its best just to
use above rules !
You will get some practice when Gary does a
problem
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Normal Eye
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Far-sighted
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Near-sighted
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Near-sighted
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Two people who wear glasses are camping. One of
them is nearsighted and the other is farsighted.
Which person's glasses will be useful in
starting a fire with the sun's rays? A) the
farsighted person's glasses B) the nearsighted
person's glasses
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A person with normal vision (near point 28cm) is
standing in front of a plane mirror. What is the
closest distance to the mirror the person can
stand and still see himself in focus? A) 14cm
B) 28cm C) 56cm
If he stands 14 cm away from the mirror, the
persons image will appear 14 cm behind the
mirror. Thus, the image will be 28 cm away.
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A parallel laser beam of width w1 is incident on
a two lens system as shown below. Each lens is
converging. The second lens has a larger focal
length than the first (f2 f1). What does the
beam look like when it emerges from the second
lens?
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A parallel laser beam of width w1 is incident on
a two lens system as shown below. Each lens is
converging. The second lens has a larger focal
length than the first (f2 f1). What does the
beam look like when it emerges from the second
lens? A) The beam is converging B) The
beam is diverging C) The beam is parallel to the
axis with a width to the axis with a width w1 E) The beam is
parallel to the axis with a width w1
CD
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The Large Synoptic Survey Telescope
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(No Transcript)
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(No Transcript)
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How to make a big telescope mirror
52,000 lbs of borosilicate glass when filled
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Trick to making a big parabolic piece of glass
Melt it spin it
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Multiple Lenses Exercises
Two converging lenses are set up as shown. The
focal length of each lens is 47 cm. The object
is a light bulb located 70 cm in front of the
first lens.
s170 cm
f47 cm

• What is the nature of the image from the first
  lens alone?
• REAL (B) REAL (C) VIRTUAL (D)
  VIRTUAL
• UPRIGHT INVERTED
  UPRIGHT INVERTED

PICTURES
EQUATIONS
Draw Rays as above
s f
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Multiple Lenses Exercises
Two converging lenses are set up as shown. The
focal length of each lens is 47 cm. The object
is a light bulb located 70 cm in front of the
first lens.
Lens separation 2 m
s1 70 cm
f 47 cm
s1 1.43 m

• What is the object distance s2 for lense 2?
• s2 -1.43 m (B) s2 1.43 m (C)
  s2 -0.57 m (D) s2 0.57 m (E) s2
  2.7 m

THE OBJECT FOR THE SECOND LENS IS THE IMAGE OF
THE FIRST LENS
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Multiple Lenses Exercises
Two converging lenses are set up as shown. The
focal length of each lens is 47 cm. The object
is a light bulb located 70 cm in front of the
first lens.
Lens separation 2 m
s170 cm
f47 cm
s1 1.43 m
s2 0.57 m

• What is the nature of the FINAL image in terms of
  the ORIGINAL object?
• REAL (B) REAL (C) VIRTUAL (D)
  VIRTUAL
• UPRIGHT INVERTED
  UPRIGHT INVERTED

PICTURES
EQUATIONS
Draw Rays as above
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Multiple Lenses Exercises
Suppose we increase the initial object distance
to 74 cm
Lens separation 2 m
s174 cm
f47 cm

• How does the L, the distance to the FINAL image,
  change?
• L increases (B) L decreases
  (C) L remains the same

Step through images, one at a time
EQUATIONS
WORDS
Increasing s1 will decrease s1 (moving closer
to focal point would increase the image distance)
Decreasing s1 will increase s2 Increasing s2
will decrease s2
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Multiple Lenses Exercises
Suppose we now decrease the initial object
distance to 58 cm. Applying the lens equation,
we find s1 2.48m
Lens separation 2 m
s1 58 cm
f 47 cm
s1 2.48 m

• What is the object distance s2 for lense 2?
• s2 -0.48 m (B) s2 0.48 m (C) s2
  -2.48 m (D) s2 2.48 m (E) s2 2.58
  m

THE OBJECT FOR THE SECOND LENS IS THE IMAGE OF
THE FIRST LENS
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Multiple Lenses Exercises
Suppose we now decrease the initial object
distance to 58 cm. Applying the lens equation,
we find s1 2.48m
Lens separation 2 m
s158 cm
f47 cm
s1 2.48 m
s2 -0.48 m

• What is the nature of the FINAL image in terms of
  the ORIGINAL object?
• REAL (B) REAL (C) VIRTUAL (D)
  VIRTUAL
• UPRIGHT INVERTED
  UPRIGHT INVERTED

PICTURES
EQUATIONS
Draw Rays as above
M M1M2
inverted image