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Exam3 - 1 ..............................................................................................2
1 con't ....................................................................................................3
Exam3 - 2 ..............................................................................................4
Exam3 - 3 ..............................................................................................5
Exam3 - 4 ..............................................................................................6
Exam3 - 5 ..............................................................................................7
Exam3 - 6 ..............................................................................................8
Exam3 - 7 ..............................................................................................9
7 con't ..................................................................................................10
Exam3 - 8 ............................................................................................11
Name:&&__________________________________________________________________________________&
Dr.&Finn/McColgan&
Exam%3%
Spring&2012&
PHYS&140&
Directions: Complete each problem to the best of your ability. Be sure to show all of your work and check your
units. Good luck!
1.
&
A proton is fired with a speed of 1.0 x 106 m/s
through the parallel plate capacitor shown at
right. The capacitor’s electric field is 2.0 x
105 V/m, down.
a. What magnetic field (give strength
and direction) must be applied to
allow the proton to pass through the capacitor with no change in speed or
direction?
b. Find the electric and magnetic fields in the proton’s reference frame.
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1 con't
Name:&&__________________________________________________________________________________&
Dr.&Finn/McColgan&
Exam%3%
2.
&
When the Voyager 2 spacecraft passed Neptune in 1989, it was 4.8 x 109 km from
earth. Its radio transmitter, with which it sent back data and images, broadcast
with a mere 22W of power. Assuming that the transmitter broadcast equally in all
directions,
a. What signal intensity was received on the earth?
b. What electric field amplitude was detected?
Spring&2012&
PHYS&140&
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37C9
Name:&&__________________________________________________________________________________&
Dr.&Finn/McColgan&
Exam%3%
3.
&
A 120-m-long train is heading for an 86-m-long tunnel. If the train moves
sufficiently fast, is it possible, according to experimenters on the ground, for the
entire train to be in the tunnel at one instant of time? Explain, and justify your
answer mathematically.
Spring&2012&
PHYS&140&
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Dr.&Finn/McColgan&
Exam%3%
4.
&
(a) How fast must a rocket travel on a journey to and from a distant star so that the
astronauts age 7 years while the Mission Control workers on earth age 100 years?
(b) As measured by Mission Control, how far away is the distant star?
Spring&2012&
PHYS&140&
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Dr.&Finn/McColgan&
Exam%3%
5.
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A whistle you use to call your hunting dog has a frequency of 20.5 kHz, but your
dog is ignoring it. You suspect the whistle may not be working. But you can’t
hear sounds above 20 kHz. To test it, you ask a friend to blow the whistle. Then,
you hop on your bicycle. In which direction should you ride (toward or away
from your friend) and at what minimum speed to know if the whistle is working?
Is that a reasonable speed for a bike?
Spring&2012&
PHYS&140&
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Dr.&Finn/McColgan&
Exam%3%
6.
&
The lowest note on a grand piano has a frequency of 27.5 Hz. The entire string is
2.20 m long and has a mass of 420 g. The vibrating section of the string is 2.05 m
long. What tension is needed to tune this string properly?
Spring&2012&
PHYS&140&
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Name:&&__________________________________________________________________________________&
Dr.&Finn/McColgan&
Exam%3%
7.
&
In a double-slit interference experiment, which of the following actions (perhaps
more than one) would cause the fringe spacing to decrease? (a) Increasing the
wavelength of the light. (b) Increasing the slit spacing. (c) Increasing the distance
to the viewing screen. (d) Submerging the entire experiment in water. Include a
picture.
Spring&2012&
PHYS&140&
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7 con't
Name:&&__________________________________________________________________________________&
Dr.&Finn/McColgan&
Exam%3%
8.
&
&
A 0.45-mm-diameter hole is illuminated by light of wavelength 450 nm. What is
the width (in mm) of the central maximum on a screen 1.8 m behind the slit?
Spring&2012&
PHYS&140&
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