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PHYS 1112 In-Class Exam #1A Tue. Feb. 8, 2011, 09:30am-10:45am

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PHYS 1112 In-Class Exam #1A Tue. Feb. 8, 2011, 09:30am-10:45am
Physics 1112
Spring 2011
University of Georgia
Instructor: HBSchüttler
PHYS 1112 In-Class Exam #1A
Tue. Feb. 8, 2011, 09:30am-10:45am
This is a closed-book, closed-notes exam, but you are permitted to bring and use a clean
copy of the official Formula Sheet for this exam, which you should have printed out from the
PHYS1112 web page.
The exam consists of 12 multiple-choice questions. Each question is worth one raw score
point. There will be no penalty for wrong answers. No partial credit will be given. I
recommend that you read all the questions at the start so that you can allocate your time
wisely. (Answer the easy questions first!)
You may use a scientific calculator for arithmetic only; your calculator must be non-graphing,
non-programmable, and non-algebraic. You are not allowed to share your calculator. The
use of cell phones, pagers, PDAs, or any other electronic devices (besides calculators) is
forbidden. All such gadgets must be turned off and put away; distractions caused by these
devices will not be tolerated.
• Do not open the exam until you are told to begin.
• Make sure the scantron sheet has your name and your UGA Card ID (810-...)
number filled in. Make sure you also have entered your name, UGA Card ID number
and signature on the exam cover page (this page!) below.
• At the end of the exam period you must hand in both your scantron sheet and this
entire exam paper, with cover page signed and with your name and UGA Card ID
(810-...) number filled-in.
• Your exam will not be graded, and you will receive a score of zero, if you do not
hand in both a properly filled in scantron sheet and this entire exam paper with
properly filled-in and signed exam cover page.
• You have until the end of the class period (i.e. until 10:45am for Period 2 Class, until
12:15pm for Period 3 Class) to finish the exam and hand in the required exam materials
described above.
By signing below, you indicate that you understand the instructions for this exam and agree
to abide by them. You also certify that you will personally uphold the university standards
of academic honesty for this exam, and will not tolerate any violations of these standards by
others. Unsigned exams will not be graded.
Name (please print):
UGACard ID (810-...) #:
Signature:
1
Physics 1112
Spring 2011
University of Georgia
Instructor: HBSchüttler
WORKSPACE
2
Physics 1112
Spring 2011
University of Georgia
Instructor: HBSchüttler
Conceptual Problems
Problem 1: A student runs northward at 5m/s, away from a vertical plane mirror, while
the mirror, mounted on wheels, travels northward at 7 m/s (with both speeds given relative
to the ground). The speed at which the student’s image moves and its direction, relative to
the ground, is
(A)
(B)
(C)
(D)
(E)
3m/s
3m/s
2m/s
9m/s
9m/s
northward
southward
northward
northward
southward
Problem 2: UGA waves (we didn’t cover those in class, but they do obey Snell’s law!) have
a speed of wave propagation vA = 2097m/s in apple juice and vB = 522m/s in butter milk.
Also, assume that sin(14.414o ) = 522/2097 . A narrow beam of UGA waves striking a
flat horizontal interface between apple juice and butter milk, with the apple juice above
and the butter milk below the interface
(A) will not undergo total internal reflection if incident from above the interface with
an angle of incidence of 29.0o ;
(B) will always have an angle of refraction not exceeding 14.414o if the beam is incident
from below the interface without total internal reflection;
(C) will undergo total internal reflection if incident from above the interface with an
angle of incidence of 8.5o ;
(D) will not undergo total internal reflection if incident from below the interface with
an angle of incidence of 29.0o ;
(E) will have an angle of refraction greater than the angle of incidence if the beam is
incident from above the interface without total internal reflection.
3
Physics 1112
Spring 2011
University of Georgia
Instructor: HBSchüttler
Problem 3: Two identically shaped solid blocks, S and T , made from the two different
transparent materials, are immersed in the same liquid L. A ray of light strikes each block
at the same angle of incidence, as shown. According to the figure below, what is the relative
magnitude of the indices of refraction of the solid blocks, nS and nT , and liquid, nL ?
L
L
S
(A)
(B)
(C)
(D)
(E)
nT
nS
nT
nL
nS
T
< nL < nS ;
< nT < nL ;
< nS < nL ;
< nS < nT ;
< nL < nT .
Problem 4: If a virtual object (d < 0) is presented to a divergent lens (f < 0), at an
absolute distance |d| less then the absolute focal length |f |, i.e., |d| < |f |, then the image is
(A)
(B)
(C)
(D)
(E)
virtual, inverted and enlarged in height relative to the virtual object
virtual, inverted and reduced in height relative to the virtual object
virtual, erect and reduced in height relative to the virtual object
real, inverted and enlarged in height relative to the virtual object
real, erect and enlarged in height relative to the virtual object
4
Physics 1112
Spring 2011
University of Georgia
Instructor: HBSchüttler
Numerical Problems
Problem 5: The state highway patrol radar guns send out a a microwave frequency of
8.090GHz. You have just passed, and are receding from, a radar speed trap driving 29.3m/s
and the radar gun measures the frequency of the microwave reflecting from your car. How
does this reflected microwave frequency, as detected by the receiver on the radar gun, differ
from the original frequency sent out by the gun ?
(A)
(B)
(C)
(D)
(E)
The
The
The
The
The
reflected
reflected
reflected
reflected
reflected
is
is
is
is
is
790Hz higher than the original frequency.
1580Hz higher than the original frequency.
395Hz lower than the original frequency.
1580Hz lower than the original frequency.
790Hz lower than the original frequency.
Problem 6: Visible light has a range of wavelengths from 400nm (violet) to 700nm (red) in
vacuum. A beam of electromagnetic waves with a frequency of 714.3THz in air travels from
air into water, with indices of refraction nAir = 1.00 and nWater = 1.333. To an under-water
observer, the beam while traveling in water will
(A) have a wavelength of 420.0nm, have a frequency of 535.9THz, and be visible to the
human eye;
(B) have a wavelength of 559.9nm, have the same frequency as in air, and be visible to
the human eye;
(C) have a wavelength of 315.1nm, have the same frequency as in air, and be invisible to
the human eye;
(D) have a wavelength of 315.1nm, have a frequency of 952.2THz, and be invisible to the
human eye;
(E) have a wavelength of 315.1nm, have the same frequency as in air, and be visible to
the human eye.
Problem 7: A very thin, flat circular mirror lies flat on the floor. Hanging from the ceiling
and centered 1.6m above the mirror is a small lamp. The circular spot formed on the flat
ceiling 3.0m above the floor, by the reflection of the light from the lamp, has a radius of
1.29m. What is the radius of the mirror ?
(A)
(B)
(C)
(D)
(E)
0.45m
0.90m
0.22m
0.69m
1.38m
5
Physics 1112
Spring 2011
University of Georgia
Instructor: HBSchüttler
Problem 8: Two laser beams are passing from water through the glass wall of an aquarium
tank into air, as shown below. The glass wall is x = 34cm thick and has two parallel planar
surfaces. Both beams enter the wall at the same point, beam 1 at normal incidence, beam 2
at an angle α = 50o to the wall. The two beams’ points of exit from the wall are y = 16.6cm
apart. Air and water have indices of refraction nAir = 1.00 and nWater = 1.333, respectively.
What is the index of refraction of the glass?
x beam 2 α beam 1 y beam 1 beam 2 (A)
(B)
(C)
(D)
(E)
2.33
1.95
1.75
1.47
0.91
Problem 9: A postage stamp placed 32.00cm to the left of a lens produces an image 4.00cm
to the left of the lens. If the postage stamp is 2.48cm tall its image produced by the lens
will be
(A)
(B)
(C)
(D)
(E)
real, inverted and 19.5cm tall in absolute size.
virtual, erect and 19.5cm tall in absolute size;
virtual, erect and 0.31cm tall in absolute size;
virtual, inverted and 19.5cm tall in absolute size;
real, inverted and 0.31cm tall in absolute size;
Problem 10: What is the focal length of the lens used in Problem 9?
(A)
(B)
(C)
(D)
(E)
−28.00cm
−4.57cm
−3.56cm
+4.57cm
+3.56cm
6
Physics 1112
Spring 2011
University of Georgia
Instructor: HBSchüttler
Problem 11: A microsope produces a final image of a microbial cell (as seen through the
eyepiece) which appears to be 2.4cm in diameter and located 40.0cm from the eyepiece on
the incoming side of the eyepiece lens. If the cell has an actual diameter of 2.8 µm, what is
the angular magnification achieved with the microscope, compared to viewing the cell from
a 20.0cm nearpoint (reference) distance without instrument ?
(A)
(B)
(C)
(D)
(E)
∼ 830
∼ 1990
∼ 4290
∼ 6430
∼ 9710
Problem 12: A convergent lens (Lens1), placed to the right of a small grain of sand produces an image of the grain to the right of Lens1. If a divergent lens (Lens2) of focal length
f2 = −6.42cm is now placed somewhere to the right of Lens1, the final image produced by
Lens2 appears approximately 32.0cm to the left of Lens2. The object of Lens2 is
(A)
(B)
(C)
(D)
(E)
real and located 5.35cm to the right of Lens2
virtual and located 5.35cm to the left of Lens2
real and located 8.03cm to the right of Lens2
virtual and located 8.03cm to the right of Lens2
virtual and located 8.03cm to the left of Lens2.
7
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