G
Geometric
ti O
Optics
ti
Chapter 34
January 26, 2012
January 26, 2012
Physics 221
1
To access the applets
pp
shown in class
Go to the Study Area on the Mastering
Physics web site.
Chapter 34
January 26, 2012
January 26, 2012
Physics 221
2
Sign
g rules for
reflection and refraction..
„
The object distance is positive if it is on the same side of the
lens/mirror as the “incoming rays” (s is positive).
„
The image distance is positive if it is on the same side of the
lens/mirror as the “outgoing rays” (s’ is positive).
„
„
The radius of curvature of a spherical surface is positive when
the Center of Curvature is on the same side as the outgoing
light (R is positive).
The “lateral” magnification of a system is defined as
M = image height/object height = y(image)/y(object)
January 26, 2012
Physics 221
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Summary of Mirror Equations
January 26, 2012
Physics 221
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Physics 221
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Physics 221
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January 26, 2012
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Thin Lenses….converging
Thin lenses are formed by
th iintersection
the
t
ti off ttwo
surfaces.
Two Spherical Surfaces
A Sphere and a plane
January 26, 2012
Physics 221
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and diverging lenses…
January 26, 2012
Physics 221
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Focusing properties
of a thin lens
S ll’ Law
Snell’s
L
is
i obeyed
b
d att each
h interface
i t f
off the
th lens.
l
Parallel light
g enters the lens.
Light is focused to a point after the lens
January 26, 2012
Physics 221
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Lens Conventions..
„
The focal length is positive for a converging lens and negative
for a diverging lens.
„
The object
Th
bj t distance
di t
is
i positive
iti if it iis on the
th same side
id off the
th
lens as the “incoming rays”.
„
The image distance is positive if it is on the opposite side of the
lens from where the “incoming rays” originate.
„
Image distances are positive for REAL images and negative for
VIRTUAL images.
i
„
The height of the image is positive if it is “upright”.
January 26, 2012
Physics 221
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The Lens Formula…
y
y'
y y'
and
= '
= '
f s−f
s s
substituting for y and y ' and solving
1 1 1
we get
+ '=
s s
f
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Physics 221
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For thin lenses…..
1 1 1
+ '=
s s
f
Object
j
distance
January 24, 2012
Image distance
Physics 221
Focal distance
13
For thin lenses…..
Lateral Magnification
g
s
m =s
January 24, 2012
Physics 221
'
14
Lensmaker’s equation…..
⎛ 1
1 1
1 ⎞
⎟⎟
+ ' = (n − 1 )⎜⎜
−
s s
R2 ⎠
⎝ R1
and
⎛ 1
1 ⎞
1
⎟⎟
= (n − 1 )⎜⎜
−
f
R2 ⎠
⎝ R1
January 24, 2012
Physics 221
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Examples
November 22, 2011
January 24, 2012
Physics 221
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Camera
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The eye
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The magnifier
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Microscope
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Telescope
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