yang (jy6223) – Electric Potential – mostarshed – (338A1)
1
This printout should have 32 questions.
Multiplechoice questions may continue on
the next column or page – fnd all choices
beFore answering.
001
10.0 points
Two alpha particles (helium nuclei), each
consisting oF two protons and two neu
trons, have an electrical potential energy oF
6
.
18
×
10
−
19
J
.
Given:
k
e
= 8
.
98755
×
10
9
N m
2
/
C
2
, q
p
=
1
.
6021
×
10
−
19
C
,
and
g
= 9
.
8 m
/
s
2
.
What is the distance between these parti
cles at this time?
Answer in units oF m.
002
10.0 points
In a charging process, 4
×
10
13
electrons are
removed From one metal sphere and placed on
a second sphere. Initially both metal spheres
were neutral. AFter the charging process the
electrical potential energy associated with the
two spheres is Found to be
−
0
.
06 J
.
What is the distance between the two
spheres? The value oF the Coulomb constant
is 8
.
98755
×
10
9
N
·
m
2
/
C
2
and the elemental
charge is 1
.
6
×
10
−
19
C
.
Answer in units oF m.
003
10.0 points
A test charge +
q
is brought to a point
A
a
distance
r
From the center oF a sphere having
a net charge +
Q
. Next, a test charge +3
q
is
brought to a point
B
a distance 3
r
From the
center oF the sphere.
Compared with the electrostatic potential
at
A
, the electrostatic potential at
B
is
1.
smaller.
2.
greater.
3.
the same.
004
10.0 points
The potential di±erence between a storm
cloud and the ground is 2
.
28
×
10
8
V.
IF a bolt carrying 3 C Falls From a cloud to
Earth, what is the change oF potential energy
oF the charge?
Answer in units oF J.
005 (part 1 of 2) 10.0 points
An object with a charge 5 C and a mass
0
.
5 kg accelerates From rest to a speed oF
20 m
/
s.
Calculate the kinetic energy gained.
Answer in units oF J.
006 (part 2 of 2) 10.0 points
Through how large a potential di±erence
did the object Fall?
Answer in units oF V.
007 (part 1 of 2) 10.0 points
A long cylindrical insulator has a uniForm
charge density oF 1
.
48
μ
C
/
m
3
and a radius oF
4 cm
.
4 cm
2 cm
What is the electric feld inside the insulator
at a distance oF 2 cm?
Answer in units oF N
/
C.
008 (part 2 of 2) 10.0 points
How much work must you do to bring a
q
=
0
.
072
μ
C test charge From 10 cm to 2 cm?
Answer in units oF J.
009
10.0 points
Suppose that the Earth (assumed spherical)
has a net charge that is not zero.
Without speciFying the electric potential
at
∞
, is it permissible to adopt the surFace
oF the Earth as a standard reFerence point
oF potential and assign the electric potential
V
= 0 to it?
1.
Yes, and there is no restriction on the sign
oF the charge.
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2
2.
No. If the net charge is not zero, the
potential should never be assigned to 0.
3.
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 Spring '11
 Mostarshed
 Physics, Electric Potential, Electrostatics, Potential Energy, Electric charge, Scalar potential

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