Physics 212 Lecture 28, Slide 1

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Physics 212 Lecture 28
Optical Devices
Great work on hour exam 3!!!!
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Final Exam FAQ
What will the exam be like? About 50 questions
evenly distributed over entire course
How do we study for this FINAL?!?!?!?!?!?!?!?!?
Old hour exams are good for most of the
material Homework and Quizzes are best for new
material
Will there be extra office hours? Extra office
hours will be posted on the web PES Room 311,
317 from 2-4 pm on Thursday.
What do I need to get on the final to get a good
grade in physics 212? Look on our web site under
course description.
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Can we perform this experiment with the
iclickers? Tell everyone that the answer choice
(A through E) with the lowest percentage will get
a bonus point. Then show the bar graph with the
percentages for a minute while people
choose/change their answer and see what happens!
PLEEEEEEEEEEAAAAAAAAAAAAASSSSSSSSSSSSSEEEEEEEEEEEE
!
i hope ull miss us, cause ill miss u.
I am having a hard time visualizing how these
lenses work, if we could slowly step through the
process for analyzing them that would be great!
My last preflight question for PHYS 212!!! Nice!
OH....I mean....how terribly sad
This class was fun. Thank you.
PARTY?! DEMO till we drop! test...this friday
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its the last lecture, and i have yet to see
something of mine put up on the screen. i really
must make this one count. i suppose some
statement of obvious fact would be appropriate,
so here WHITE SOX gt CUBS
Play "Thé à la Menthe" from Ocean's Twelve
Soundtrack before class plzzzz, I might even
breakdance for the class (if my swollen finger
allows).
Since I probably won't fill out the ICES form, I
just wanted to take this opportunity to say
thanks for this little box at the end of the
preflight. Every time lecture got painful I would
just tell myself it's ok, remember how your
comment made it up on the power point last
tuesday.... (this would be a good time to put
this comment up on the power point to convince me
and my peers to fill out the ICES or forever hold
your peace)
HAVE A GREAT SUMMER!!!
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Executive Summary - Lenses
real inverted bigger
2f gt S gt f
virtual upright bigger
f gt S gt 0
virtual upright smaller
S gt 0
diverging
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Executive Summary - Mirrors
real inverted bigger
2f gt S gt f
concave
f
virtual upright bigger
f gt S gt 0
virtual upright smaller
S gt 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 !
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Multiple Lens/Mirror Summary

• Image from first becomes object for second.
• Object distance positive if up stream of
  mirror/lens

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Normal Eye
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Far-sighted
Converging Lens creates virtual image at
persons near point
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Near-sighted
I just want to find out what the diopters for my
prescription contacts actual mean, because I'm
-8.5 and all I know is that I'm pretty close to
blind
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Near-sighted
Fix with diverging lens that creates virtual
image at far point.
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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 gt f1). What does the
beam look like when it emerges from the second
lens?
Oooh I have no idea..
i sketched it
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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 gt 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 lt w1 D) The beam is parallel
to the axis with a width w1 E) The beam is
parallel to the axis with a width gt w1
CD
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The Large Synoptic Survey Telescope
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How to make a big telescope mirror
52,000 lbs of borosilicate glass when filled
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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 gt 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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Thanks for a GREAT semester!