Name: ________________________
Exam 1--PHYS 102--S16
Multiple Choice
Identify the choice that best completes the statement or answers the question.
1. The up-quark, u, has an elementary charge of
+(2/3)e and the down-quark, d, of -(1/3)e. What
combination of three of these quarks makes up a
neutron?
a. uud
b. udd
c. ddd
d. uuu
4. Doug rubs a piece of fur on a hard rubber rod,
giving the rod a negative charge. What happens?
a. The fur is left neutral.
b. The fur is also charged negatively.
c. Electrons are added to the rod.
d. Protons are removed from the rod.
5. Two electrons and a third charged particle are
located at different positions along a straight line.
Both electrons experience zero net force due to
static electricity. Is the charge on the third particle
positive or negative, and where must it be located
on the line, relative to the electrons?
a. negative, in between the electrons
b. positive, in between the electrons
c. negative, with both electrons on the same side
d. positive, with both electrons on the same side
2. You bring a negatively charged rod near to a
neutral copper wire, as in this figure. Which of
these statements is true?
6. The diagram shows three heavily charged plastic
cubes. The net force on cube #3 is shown. If cube
#3 is positively charged, what are the charges on
cubes 1 and 2, respectively?
a.
b.
c.
d.
e.
The wire will move away from the rod
Negative charges will move to the right-hand
side of the wire.
Nothing will happen unless the two objects
touch
Positive charges will move to the left-hand side
of the wire.
Negative charges will move to the center of the
wire.
a.
b.
c.
d.
3. Imagine two charges, A & B. Charge A is attracted
to a positive charge. Charge B is repelled from a
negative charge. What happens if you bring
charges A& B near to one another?
a.
b.
c.
d.
they attract
they repel
nothing; they neither attract nor repel
there is not enough information; you must
know the charge of A & B
1
cube 1 is positive; cube 2 is negative
cube 1 is positive; cube 2 is positive
cube 1 is negative; cube 2 is positive
cube 1 is positive; cube 2 is negative
9. The force between two charges, which are
separated by 4 m, is 12 N. If the two charges are
brought closer to a distance of 2 m, what is the
force?
a. 48 N
b. 24 N
c. 12 N
d. 6 N
e. 3 N
7. What is the magnitude of the force on the +2 nC
charge in this figure?
10. This figure shows 2 metal spheres that each have a
charge. If q2 has a charge with a magnitude of 3 C,
what is the charge on q 1?
a.
b.
c.
d.
e.
0N
5.1x10-8 N
1.0x10-8 N
1.3x10-7 N
1.8x10-8 N
a.
b.
c.
d.
8. For the figure in the previous question, what is the
direction of the force on the 2 nC charge?
a.
b.
c.
d.
e.
11° above the -x axis
37° above the +x axis
11° above the +x axis
along the -y axis
53° below the -x axis
2
+1.5 C
+6 C
-3 C
+11 C
11. For this figure, what is the magnitude of the
electric field at point A?
13. Electric field is _______________.
a. a measure of energy per unit charge.
b. a measure of force per unit charge.
c. a conservative force.
d. always quantized.
e. equal to the force on a charged particle.
14. Consider this configuration of charges. At what
point is the electric field equal to zero? (Point C is
equidistant between the 2 charges.)
a.
b.
c.
d.
e.
a.
b.
c.
d.
e.
a
b
c
d
e
15. A proton is accelerated by a constant electric field
of magnitude 220 N/C; the proton is moving in the
same direction as the electric field. What is the
proton’s velocity after 1x10 -6 s?
2.0 N/C
3.0 N/C
2.2 N/C
1.0 N/C
1.4 N/C
12. For the figure in the previous question, what is the
direction of the electric field at point A?
a.
b.
c.
d.
a.
b.
c.
d.
e.
237º from the +x axis
63º below the +x axis
in the -y direction
27º above the +x axis
in the +x direction
2.1x1010 m/s
3.5x10-23 m/s
2.1x104 m/s
0.021 m/s
16. A parallel-plate capacitor initially has a potential
difference of 10 V and is then disconnected from
the charging battery. If the area of the plates is
now doubled, what is the new value of the voltage?
a.
b.
c.
d.
e.
3
2.5 V
5V
10 V
20 V
40 V
19. This diagram shows a collection of charges. At
which point is the potential equal to zero?
17. A parallel-plate capacitor has dimensions 0.04 m ×
0.05 m. The plates are separated by a 1.0 x10 -3 m
thickness of paper (dielectric constant κ = 3.7).
What is the charge that can be stored on this
capacitor, when connected to a 1.5-V battery?
a.
b.
c.
d.
e.
a.
b.
c.
d.
e.
4.8 × 10−12 C
20 × 10−12 C
1.9 × 10−10 C
4.8 × 10−11 C
9.8 × 10−11 C
20. Which of these is a unit for the electric potential?
J
I.
C
II. Volts
kg m2
III. 4
s C
18. Inserting a dielectric material between two charged
parallel conducting plates, originally separated by
air and disconnected from a battery, will produce
what effect on the capacitor?
I. Increase charge on the capacitor
II. Increase voltage of the capacitor
III. Increase capacitance of the capacitor
IV. Decrease capacitance of the capacitor
a.
b.
c.
d.
e.
a
b
c
d
at all points
a.
b.
c.
d.
e.
IV only
III only
I, II, and III
II & IV
I & III
4
I
I & II
II & III
I & III
all of these are units for the potential
24. This figure shows two charges. What is the
potential at point A?
21. For this scenario, where is the electric potential the
least?
a.
b.
c.
d.
e.
both A & D
B
C
A
both C & B
a.
b.
c.
d.
e.
22. The electric potential 1m from a certain charged
particle is 4 times the potential at 1m from a second
particle. How do the particles’ charges compare?
a. The first particle has one-quarter (1/4) the
charge of the second particle.
b. The first particle has 2 times the charge of the
second particle.
c. The first particle has one-half the charge of the
second particle.
d. The first particle has 4 times the charge of the
second particle.
23. If the distance between two negative point charges
is increased by a factor of three, the resultant
potential energy is what factor times the initial
potential energy?
a. 9.0
b. 1/9
c. 3.0
d. 1/3
5
-9 V
27 V
18 V
-10 V
-18 V
ID: A
Exam 1--PHYS 102--S16
Answer Section
MULTIPLE CHOICE
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B
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