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Form 1
Physics 240
First Practice Exam
Winter 2007
1. Last Name:___________________
First Name:_____________________
2. Please circle your discussion instructor and section below:
Instructor
Time
Section
Instructor
Time
Section
Krisch
1011
010
Lubensky
89
007
Krisch
1112
011
Lubensky
910
008
Krisch
121
012
Lubensky
1011
009
Chupp
121
013
Chupp
12
014
Chupp
23
015
3. Fill in your name, 8 digit student ID number, discussion section number, and
the exam FORM number on the scantron sheet
4. There are 20 multiple choice problems worth 5 points each for a total of 100
points.
Choose the one best answer and transfer it to the scantron sheet.
You
must mark the correct answer on the scantron sheet to get credit for the
problem.
There is no penalty for guessing, so be sure to enter an answer for
every question even if it is just a best guess.
5. At the end of the exam hand in both your scantron and exam booklet in
separate piles set up by the proctors.
6. This is a closed book, 90 minute exam. Turn off and put away all electronic
devices. You may use a calculator and one 3”x5” note card
k = 1/4πε
0
=9x10
9
Nm
2
/C
2
ε
0
= 8.85x10
12
C
2
/Nm
2
e = 1.6x10
19
C
1 eV= 1.6x10
19
J
μ = micro =10
6
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View Full Document 2. In the above problem how much work is required of an
external
force to bring an
electron in from infinity to the origin?
a)
0
b)
1.4 x 10
15
J
c)
 1.4 x 10
15
J
d)
2.9 x 10
15
J
e)
 2.9 x 10
15
J
1.
Four point charges, either + or  1 μC (10
6
C) as shown, are positioned on the x and y
axes each one meter from the origin.
What is the magnitude of the electric field at the
origin?
a)
0
b)
9.0 x 10
3
N/C
c)
1.8 x 10
4
N/C
d)
2.5 x 10
4
N/C
e)
3.6 x 10
4
N/C
+
+


1 m
+
+


1 m
4.
Three concentric, thin, uniformly charged spherical shells (A, B, and C) have radii of
1m, 2m, and 3m respectively.
At the center of the shells is a +12 μC point charge.
The
shells have charges of Q
A
=14 μC, Q
B
=6 μC, and Q
C
=14 μC.
(1μC = 10
6
C)
Rank the magnitude of E just above the outer surface of each shell.
a) E
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This note was uploaded on 04/02/2008 for the course PHYSICS 240 taught by Professor Davewinn during the Winter '08 term at University of Michigan.
 Winter '08
 DaveWinn
 Physics

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