Download Chapter 19 Optical Instruments Reading Quiz Answer Reading Quiz

Chapter 19
Optical Instruments
Reading Quiz
1. The units of refractive power are
A. watts.
B. m2.
C. m–1.
D. joules.
Topics:
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•
•
•
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The thin-lens equation
The camera
The human eye
The magnifier
The microscope
The telescope
Resolution of optical
instruments
Sample question:
This anablepsis is called the “four-eyed
“four
fish.” How must the top
half of its eye differ from the lower half so that it has clear vision
both above and below the waterline at the same time?
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Answer
Reading Quiz
1. The units of refractive power are
2. Accommodation of the eye refers to its ability to
A. focus on both nearby and distant objects.
B. move in the eye socket to look in different directions.
C. see on both the brightest days and in the dimmest light.
D. see both in air and while under water
C. m–1.
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Answer
Reading Quiz
2. Accommodation of the eye refers to its ability to
A. focus on both nearby and distant objects.
3. The magnification of a microscope is increased when
A. the focal length of the objective lens is increased.
B. the focal length of the objective lens is decreased.
C. the focal length of the eyepiece is increased.
D. the distance between the objective lens and eyepiece is
decreased.
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Answer
Reading Quiz
3. The magnification of a microscope is increased when
4. The fundamental resolution of an optical instrument is set by
A. the accuracy to which lenses can be polished.
B. the fact that white light is composed of all visible colors.
C. the fact that all types of glass have nearly the same index
of refraction.
D. the wave nature of light.
C. the focal length of the eyepiece is increased.
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Answer
The Thin-Lens Equation
4. The fundamental resolution of an optical instrument is set by
D. the wave nature of light.
1 1 1
+ =
s s′ f
Thin-lens
lens equation (also works for mirrors)
relating object and image distance to focal length
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Sign Conventions for Lenses and Mirrors
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The Camera
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Focusing a Camera
Digital Cameras
A digital image is made up
of millions of pixels.
A CCD chip records the
digital image.
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The Human Eye
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Focusing and Accommodation
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Correcting Myopia
Myopia and Hyperopia
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The Magnifier
Apparent Size
Largest angular size
without a magnifier is
θ0 ≈
h
25 cm
With a magnifier,
the angular size is
h
θ0 ≈
f
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The magnification is thus
M=
θ 25 cm
=
θ0
f
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The Microscope
The Microscope
M = MoMe = −
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L 25 cm
f0 fe
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Lens Aberrations: Spherical Aberration
The Telescope
M =−
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The Hubble space
telescope originally
suffered from
spherical aberration.
f0
fe
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Chromatic Aberration
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Resolution and the Wave Nature of Light
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Rayleigh’s Criterion
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The Resolution of a Microscope
Two objects are resolvable if their
angular separation is greater than
Numerical aperturre NA = nsin φ0
1.22 λ
θ1 =
D
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Resolving power RP
P = dmin =
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0.61λ0
NA
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Optical and Electron Micrographs of e. coli
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