PH 211 07-11-2014 Physics 211 Exam-1 NAME: _____________________________________ Write down your name also on the back of your exam. SIGNATURE and ID: ___________________________ Return this hard copy exam together with your other answer sheets. Write down your name on the back of the package of sheets you turn in. Show all your procedures when giving the answer to the questions. Use additional sheets of paper if necessary 1. 1A The figure below shows 4 spheres of different radius, with charge uniformly distributed through its volume. (5 points) Rank the spheres according to their volume charge density,, greatest first a) I , II , III , IV b) I , II , IV, III c) III , IV, I, II d) IV , III , II, I e) NA (5 points) Rank the spheres according to the magnitude of the electric field they produce at P, greatest first a) I = II , III = IV b) I = II , III, IV c) III=IV, I, II d) IV , III , II, I e) NA
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PH 211 07-11-2014 Physics 211 Exam-1 211 07-11-2014 Physics 211 Exam-1 NAME: _____ Write down your name also on the back of your exam. SIGNATURE and ...
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PH 211 07-11-2014
Physics 211 Exam-1
NAME: _____________________________________ Write down your name also on the back of your exam.
SIGNATURE and ID: ___________________________ Return this hard copy exam together with your other answer sheets. Write down your name on the back of the package of sheets you turn in.
Show all your procedures when giving the answer to the questions. Use additional sheets of paper if necessary
1. 1A The figure below shows 4 spheres of different radius, with charge uniformly distributed through its volume.
(5 points) Rank the spheres according to their volume charge density,, greatest first
a) I , II , III , IV b) I , II , IV, III c) III , IV, I, II
d) IV , III , II, I e) NA
(5 points) Rank the spheres according to the magnitude of the electric field they produce at P, greatest first
a) I = II , III = IV b) I = II , III, IV c) III=IV, I, II
d) IV , III , II, I e) NA
1B. There exist a non-uniform electric field E
(x, y, z) = 5 y j (with y in meters,
and E in N/C). The figure shows a Gaussian surface (a cube of side L= 4 m.)
X
Y
Z
L = 4 m
A
B C
D
E
F
(5 points) The total flux through the gaussian surface is (in units of N.m2/C):
a) 40 b) 320 c) 100 d) zero e) NA
(5 points) The total charge inside the gaussian surface is (in units of Coulomb): a) 1.87 x 10-12 b) 3.58 x 10-10 c) 0.12 x 10-9 d) 2.83 x 10-9 e) NA
1C (5 points) The figure (see next page) shows two point charges of charge +3q and
– q respectively located along long the x-axis and equidistance from the origin. Draw, approximately to scale, the electric field lines everywhere in the whole space around and beyond the location of the charges. In particular indicate the orientation of the electric field lines passing through the discrete points indicated in the figure (The dashed lines are shown just for reference).
(Use this graph to provide your answer to question 1C)
1D (5 points) The figures below show two separate cases, where all the different objects have positive charge uniformly distributed; Q > q and Q2 > q1. The figure on the left shows two solid spheres, of different radius, separated by a distance “d”. The figure on the right shows a small solid sphere in front of a thin bar of length “L”. Assuming that the charges are uniformly distributed all over the volume of the corresponding object, indicate which of the following statement(s) is (are) correct:
q Q
d
L
Q2
q1
a
a) The magnitude of the electrostatic force acting on the sphere of charge Q is
greater than the magnitude of the electrostatic force acting on the sphere of
charge q.
b) The magnitude of the electrostatic force acting on the sphere of charge Q is
lower than the magnitude of the electrostatic force acting on the sphere of
charge q.
c) The magnitude of the electrostatic force acting on the thin bar of charge Q2 is:
2
12
0
2
La
4
1
qQ
F
d) The magnitude of the electrostatic force acting on the sphere of charge q1 is:
2
12
0 a4
1 qQF
e) All the expressions above are incorrect.
1E (5 points) The four particles for a square of edge length a= 5 cm. The values of the charges are: