ame: ________________________ Class: ___________________ Date: __________
Exam 1--PHYS 102--Spring 2013
Multiple Choice
Identify the choice that best completes the statement or answers the question.
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1. A metallic object holds a charge of −3.8 × 10−6 C. What total number of electrons does this represent?
a. 6.1 × 1013
b. 2.4 × 1013
c. 1.6 × 1014
d. 4.2 × 1014
2. Which of the following best characterizes electrical insulators?
a. they have a high tensile strength
b. electric charges move freely within the material
c. they are good heat conductors
d. charges in the material don't move
3. Two point charges are 4 cm apart. They are moved to a new separation of 2 cm. By what factor does the
resulting mutual force between them change?
a. 1/4
b. 2
c. 4
d. 1/2
4. In a thundercloud there may be an electric charge of +40 C near the top of the cloud and −40 C near the
bottom of the cloud. These charges are separated by about 2.0 km. What is the electric force between these
two sets of charges?
a. 3.6 × 104 N
b. 3.6 × 105 N
c. 3.6 × 106 N
d. 3.6 × 107 N
5. Electric field is dimensionally equivalent to which of the following?
a. N⋅m/C
b. N/C2
c. N/C
d. N⋅m2/C2
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ame: ________________________
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6. Charges of 4.0 µC and 2.0 µC are placed at two corners of a right triangle as shown. What is the magnitude
of the electric field felt by the 2.0µC charge?
a. 0.0029 N/C
b. 7200 N/C
c. 700 N/C
d. 1400 N/C
7. For the previous problem, what is the direction of the electric field at the position of the 2.0 µC charge?
a. 53° above the -x axis
c. 137° from the +x axis
d. 37° above the -x axis
b. 37° below the +x axis
8. This figure shows two charges and their electric field lines. If the charge on the right has a magnitude of 10
µC, what is the sign and magnitude of the left charge?
a.
b.
c.
-2.5 µC
+10 µC
+6 µC
d.
e.
2
-4 µC
-10 µC
ame: ________________________
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9. Consider this configuration of charges. Which vector best represents the net force acting on the bottom
charge?
a.
b.
c.
a
b
c
d.
e.
d
e
____ 10. 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?
a. 2.1x104 m/s
c. 2.1x1010 m/s
b. 0.021 m/s
d. 3.5x10-23 m/s
____ 11. A capacitor consists of 2 metal plates with an area of 0.3 m 2 each. The plates are separated by a distance of
1x10-6 m. A piece of paper is between the two plates; this paper has a dielectric constant of 1.8. What is the
capacitance of the capacitor?
a.
b.
2.7 µF
1.5 µF
c.
d.
3
4.0 µF
4.8 µF
ame: ________________________
____ 12. What is the equivalent capacitance of this circuit?
2.0 µF
2.0 µF
1.0 µF
12 V
a. 2.0 µF
c. 10 µF
d. 0.8 µF
b. 5.0 µF
____ 13. For the circuit in the previous figure, what is the charge on the left 2.0 µF capacitor?
a. 12 µC
c. 24 µC
b. 3.0 µC
d. 6.0 µC
____ 14. Two charges are arranged on the vertices of this equilateral triangle as shown. If Q=2.0 µC, what is the
potential at the top of the triangle (where the smiley face is)?
a.
b.
12 V
144,000 V
c.
d.
4
36,000 V
18,000 V
ame: ________________________
____ 15. Two charges are arranged on the vertices of this equilateral triangle as shown in the previous figure. If
Q=2.0 µC, how much work would be required to bring a charge of value Q (2 µC) from a very large distance
away to the place at the top of the triangle (where the smiley face is)?
a. 36000 J
c. 1.8x1010 J
b. 0.072 J
d. 0.02 J
____ 16. Consider this circuit. All three capacitors are identical. What is the voltage across C 1?
C2
C1
C3
12 V
a.
b.
4V
12 V
c.
d.
5
6V
8V
ame: ________________________
____ 17. This diagram shows a collection of charges. At which point is the potential equal to zero?
a. a
b. b
c. c
____ 18. At what point is the potential greatest?
a.
b.
A
B
d.
e.
d
e
c.
d.
both the same
it depends on the magnitude of the
charge
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ame: ________________________
____ 19. What is the equivalent capacitance of this arrangement of capacitors?
a. 8.7 µF
c. 18 µF
b. 12 µF
d. 3.0 µF
____ 20. Two pieces of copper wire are the same diameter. The length of wire A is twice that of wire B. How do
their resistances compare?
d. RA=2RB
a. RA=RB
b. RA=½RB
e. RA=4RB
c. RA=¼RB
____ 21. Consider this circuit. What is the current through the resistor?
a. 4 A
c. 36 A
b. 0.25 A
d. 3 A
____ 22. When you apply a potential of 3 V to a particular electrical device, the current in 2 A. When you apply 6V,
the current is 4 A. Is this device Ohmic or Non-Ohmic?
a. Ohmic
c. Neither
b. Non-Ohmic
d. Not enough information
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ame: ________________________
____ 23. Which of these has the greater current, a incandescent light bulb (60 W) or a bathroom heater (1000 W)?
a. heater
c. both the same
b. bulb
____ 24. A 50Ω resistor is hooked up to a power supply of 150 V. What is the power dissipated across the resistor?
a. 0.33 W
b. 450 W
____ 25. Bubble A for this answer.
a. A
b. B
c.
d.
7500 W
3W
c.
d.
C
D
8
ID: A
Exam 1--PHYS 102--Spring 2013
Answer Section
MULTIPLE CHOICE
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DIF: 2
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DIF: 3
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TOP: 15.3 Coulomb's Law
TOP: 15.4 The Electric Field
TOP: 15.4 The Electric Field