Clicker (physical one) :
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You brought close three objects A, B & C to observe:
A & B repel. B & C repel.
Which of the following are true?
A. A & C have charges
of the same sign.
B. A & C have charges of
opposite sign.
C. A & B & C have
charges of the same
sign.
D. One object is neutral
E. Additional experiments
are necessary to
determine the signs of
the charges.
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You brought close three objects A, B & C to observe:
A & B attract. B & C repel.
Which of the following are true?
A. A & C have charges
of the same sign.
B. A & C have charges of
opposite sign.
C. A & B & C have
charges of the same
sign.
D. One object is neutral
E. Additional experiments
are necessary to
determine the signs of
the charges.
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What is the direction of the electric force at the
upper right corner, which is a point in empty
space? ( (e) means zero)
71%
21%
e
3%
d
3%
c
b
2%
a
A. a
B. b
C. c
D. d
E. e
What is the direction of the electric field at the
upper right corner, which is a point in empty
space?
46%
35%
17%
e
d
1%
c
b
2%
a
A. a
B. b
C. c
D. d
Suppose the +2Q charge at the lower left corner is
removed. Then the magnitude of the electric field
at the upper right corner:
52%
39%
e.
m
sa
st
he
St
ay
be
co
m
es
sm
al
ge
r.
ar
es
l
be
co
m
A. becomes larger.
B. becomes smaller.
C. Stays the same.
le
r.
9%
Object A has a charge of +2 C, and object B has
a charge of +6 C. Which statement is true about
the electric forces on the objects?
36%
34%
26%
A. FAB = -3FBA
B. FAB = 3FBA
C. FAB = -FBA
D. FAB = FBA
=F
BA
FA
B
FB
A
FA
B
=-
A
=3
FB
FA
B
FA
B
=-
3F
BA
4%
A test charge of +3 C is at a point P where an
external electric field is directed to the right and
has a magnitude of 400 N/C. If the test charge is
replaced with another test charge of -3 C, what
happens to the external electric field at P?
61%
29%
n.
a
w
ay
th
at
ca
n
...
ire
ct
io
ev
er
se
sd
It
c
ha
ng
es
i
n
It
r
su
na
ff
ec
te
d.
10%
It
i
A. It is unaffected.
B. It reverses direction.
C. It changes in a way
that cannot be
determined.
Rank the magnitudes of the electric field at points
A, B, and C shown in Figure (greatest magnitude
first).
71%
8%
,B
1%
C,
A
C,
A
B,
A,
C
B,
A,
C,
C
B
2%
,A
8%
C,
B
11%
B,
A, B, C
A, C, B
B, A, C
B, C, A
C, A, B
C, B, A
A,
A.
B.
C.
D.
E.
F.
threads hang close together as figure. One is
positively charged; the other is neutral. We can
conclude that
75%
23%
in
.. .
ea
v
lin
es
l
fie
ld
th
e
of
no
ne
of
t
e
so
m
lf
ie
ld
lin
he
es
l
ea
v
fie
ld
in
g
lin
es
th
e
le
av
i
po
s i.
..
n.
..
3%
al
A. all field lines leaving the
positively charged pith ball end
on the neutral pith ball.
B. some of the field lines leaving
the positively charged pith ball
end on the neutral pith ball.
C. none of the field lines leaving
the positively charged pith ball
end on the neutral pith ball.
A hemispherical surface (half of a spherical surface) of
radius R is located in a uniform electric field of magnitude E
that is parallel to the axis of the hemisphere. What is the
magnitude of the electric flux through the hemisphere
surface?
1.
2.
3.
4.
5.
p R2 E
4p R2 E / 3
2p R2 E / 3
p R2 E / 2
p R2 E / 3
0%
0%
p R2 E 4p R2
E/3
0%
0%
0%
2p R2 p R2 E p R2 E
E/3
/2
/3
Two concentric imaginary spherical surfaces of radius R and 2R
respectively surround a positive point charge Q located at the
center of the surfaces. When the electric flux through the surface of
radius
, the electric
through the surface of radius 2R
1 R is
 2 flux
is
1
 2  1
. 4
1.
1
2. .  2 
2  1
3. .
2  21
4. .
2  41
5. .
2
1
0%
.
0%
0%
0%
0%
.
.
.
.
Which one of the following can not be a
statement of Gauss’s Law for some physical
situation?
1.
2.
3.
4.
5.
4.pr 0E  Q
2
2.prL0E  Q
.0  E  dA    dV
.0  E  dA  
2.0EA    dA
0%
.
0%
0%
0%
0%
.
.
.
.
You are told that  E  dA summed over the surface
area of both sphere A and sphere B below is equal
to Q . You can conclude that
0
1. Sphere A contains charge qin  Q
2. Sphere B contains charge qin  Q
3. Sphere B contains charge qin  Q
Q
4. Each sphere contains charge qin  
2
5. The sum of the charges contained
in both spheres is Q
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Three originally uncharged infinite parallel planes are arranged
as shown. Then the upper plate has surface charge density 
placed on it while the lower plate receives surface charge
density – . The net charge induced on the center plate is
1.
2.
3.
4.
5.
0
–/2
+/2
–
+
0%
0%
0%
0%
0%
0
–s/2
+s/2
–s
+s
A positive point charge q is placed off center inside
an uncharged metal sphere insulated from the
ground as shown. Where is the induced charge
density greatest in magnitude and what is its sign?
1.
2.
3.
4.
5.
A; negative.
A; positive.
B; negative.
B; positive.
C; negative.
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0%
0%
0%
0%
:45
A positive point charge q is placed at the center of an
uncharged metal sphere insulated from the ground. The
outside of the sphere is then grounded as shown. Then the
ground wire is removed. A is the inner surface and B is the
outer surface. Which statement is correct?
1.
2.
3.
4.
5.
The charge on A is –q; that on B is +q.
The charge on B is –q; that on A is +q.
q
The charge is 2 on A and on B.
There is no charge on either A or B.
The charge on A is –q; there is no
charge on B.
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0%
:45
Equipotentials are lines along which
1.
2.
3.
4.
5.
the electric field is constant in
magnitude and direction.
the electric charge is constant
in magnitude and direction.
maximum work against
electrical forces is required to
move a charge at constant
speed.
a charge may be moved at
constant speed without work
against electrical forces.
charges move by themselves.
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0%
0%
0%
0%
When a charged particle is moved
along an electric field line,
1.
2.
3.
4.
5.
the electric field does no work on the
charge.
the electrical potential energy of the
charge does not change.
the electrical potential energy of the
charge undergoes the maximum
change in magnitude.
the voltage changes, but there is no
change in electrical potential energy.
the electrical potential energy
undergoes the maximum change,
but there is no change in voltage.
0%
0%
0%
0%
0%
When a negative charge is released and
moves along an electric field line, it moves to a
position of
1.
2.
3.
4.
5.
lower potential and lower
potential energy.
lower potential and higher
potential energy.
higher potential and lower
potential energy.
higher potential and higher
potential energy.
decreasing magnitude of
the electric field.
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0%
0%
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