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Ph 203 - General Physics
Final Exam
June 8, 2005
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Name:____________
Exam is closed book, closed notes. Use only your note sheet (one side of a single
page).
Use the scantron sheet to answer all multiple choice questions.
Show all your work and explain your reasoning for problems on the color papers
provided.
Partial credit may be given for the work shown even if the final answer is wrong.
No credit will be given if no work is shown (except for true/false or multiple
choices ones where you do not need to show work)
Useful Constants: 0  4  10 7 T  m
N  m2
k  9.0  10 9
C2
me  9.11  10 31 kg
A
C2
N  m2
m p  1.67  10  27 kg
 0  8.85  10 12
q e  1.6  10 19 C
1eV  1.6  10 19 J
mili (m)  10 3
micro (  )  10 6
nano(n)  10 9
Part I – MULTIPLE CHOICE. Choose the one alternative that best completes the
statement or answers the question. Bubble the appropriate circle on the scantron
sheet. You do not need to show your work for this part.
1. Consider a particle moving with constant speed such that its acceleration of constant
magnitude is always perpendicular to its velocity.
A) It is moving in a parabola.
B) It is moving in a straight line.
C) It is moving in a circle.
D) None of the above is definitely true all of the time.
2. The gravitational attractive force between two masses is F. If the masses are moved
to half of their initial distance, what is the gravitational attractive force?
A) 2F
B) F/4
C) 4F
D) F/2
3. If a solid metal sphere and a hollow metal sphere of equal diameters are each given
the same charge, the electric field (E) midway between the center and the surface is
A) greater for the solid sphere than for the hollow sphere.
B) equal in magnitude for both, but one is opposite in direction from the other.
C) zero for both.
D) greater for the hollow sphere than for the solid sphere.
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4. The charge carried by one electron is e = -1.6 × 10 C. The number of electrons
necessary to produce a charge of -1.0 C is
18
19
A) 6.25 × 10 .
B) 1.6 × 10 .
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C) 6.25 × 10 .
D) none of the given answers
Ph 203 Final Exam
Lane Community College – Spring 2005
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5. What are the units of the Coulomb (electric) constant k, which appears in Coulomb's
law?
2
2
2 2
A) N ∙m/C
B) N∙m/C
C) N/C
D) N∙m /C
6. Is it possible for a positive and a negative charge to attract each other?
A) Yes, they will attract if they are close enough.
B) Yes, they always attract.
C) Yes, they will attract if one carries a larger charge than the other.
D) No, they will never attract.
7. A negatively charged rod is brought near one end of an uncharged metal bar. The
end of the metal bar farthest from the charged rod will be charged
A) neutral.
B) negative.
C) positive.
D) none of the given answers
8. Two charged objects are separated by a distance d. The first charge is larger in
magnitude than the second charge.
A) The charges exert forces on each other equal in magnitude and pointing in the
same direction.
B) The second charge exerts a larger force on the first charge.
C) The charges exert forces on each other equal in magnitude and opposite in
direction.
D) The first charge exerts a larger force on the second charge.
9. A metal sphere of radius 2.0 cm carries a charge of 3.0 μC. What is the electric field
6.0 cm from the center of the sphere (Remember Gauss’s Law? Surface area of
sphere is 4r2)?
A) 4.2 × 106 N/C
B) 9.3 × 106 N/C
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C) 7.5 × 10 N/C
D) 5.7 × 106 N/C
10. Materials in which the electrons are bound very loosely to the nuclei and can move
about freely within the material are referred to as
A) superconductors.
B) semiconductors.
C) conductors.
D) insulators.
11. Which of the following is not a vector?
A) electric charge
B) electric force
C) electric field
D) electric line of force
12. 20 V is placed across a 15 μF capacitor. What is the energy stored in the
capacitor?
A) 300 μJ
B) 3.0 mJ
C) 150 μJ
D) 6.0 mJ
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Lane Community College – Spring 2005
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13. An equipotential surface must be
A) parallel to the electric field at any point.
B) perpendicular to the electric field at any point.
14. One coulomb per volt is a
A) watt.
B) farad.
C) electron-volt.
D) joule.
15. Two 3.00-μC charges are at the ends of a meter stick. Find the electrical potential
for the center of the meter stick.
A) 1.08 × 105 V
B) 5.40 × 104 V
C) zero
D) 2.70 × 104 V
16. Doubling the capacitance of a capacitor holding a constant charge (charge on
capacitor remains constant) causes the energy stored in that capacitor to
A) decrease to one half.
B) decrease to one fourth.
C) double.
D) quadruple.
17. A 110-V hair dryer is rated at 1200 W. What current will it draw?
A) 11 A
B) 12 A
C) 1.0 A
D) 0.090 A
18. The direction of convention current is taken to be the direction that
A) positive charges would flow.
B) negative charges would flow.
19. If the resistance in a circuit with constant current flowing is doubled, the power
dissipated by that circuit will
A) decrease to one half.
B) double.
C) decrease to one fourth.
D) quadruple.
20. A 1.0-mm diameter copper wire (resistivity 1.68 × 10-8 Ω∙m) carries a current of
15 A. What is the potential difference between two points 100 m apart?
A) 12 V
B) 23 V
C) 41 V
D) 32 V
21. Two capacitors of 6.00 μF and 8.00 μF are connected in parallel. The combination
is then connected in series with a 12.0-V battery and a 14.0-μF capacitor. What is
the equivalent capacitance?
A) 6.00 μF
B) 14.0 μF
C) 7.00 μF
D) 8.00 μF
22. As more and more capacitors are connected in parallel, the equivalent capacitance
of the combination increases.
A) never true
B) Sometimes true; it depends on the voltage of the battery to which the
combination is connected.
C) Sometimes true; it goes up only if the next capacitor is larger than the
average of the existing combination.
D) always true
Ph 203 Final Exam
Lane Community College – Spring 2005
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23. A 2.0-μF capacitor is charged through a 50-kΩ resistor. How long does it take for
the capacitor to reach 90% of full charge?
A) 2.3 s
B) 0.90 s
C) 2.2 s
D) 0.23 s
24. A circular loop of wire of radius 0.50 m is in a uniform magnetic field of 0.30T.
The current in the loop is 2.0 A. What is the magnetic torque when the plane of
the loop is parallel to the magnetic field?
A) zero
B) 0.52 m∙N
C) 0.41 m∙N
D) 0.47 m∙N
25. A 2.0-m wire carrying a current of 0.60 A is oriented parallel to a uniform
magnetic field of 0.50 T. What is the magnitude of the force it experiences?
A) zero
B) 0.60 N
C) 0.30 N
D) 0.15 N
26. A current carrying circular loop of wire lies flat on a table top. When viewed from
above, the current moves around the loop in a counterclockwise sense. What is the
direction of the magnetic field caused by this current, inside the loop? The
magnetic field
A) points straight up.
B) circles the loop in a counterclockwise direction.
C) points straight down.
D) circles the loop in a clockwise direction.
27. A charged particle is injected into a uniform magnetic field such that its velocity
vector is perpendicular to the magnetic field vector. Ignoring the particle's weight,
the particle will
A) move along a parabolic path.
B) follow a circular path.
C) move in a straight line.
D) follow a spiral path.
28. A proton has a speed of 3.0 × 106 m/s in a direction perpendicular to a uniform
magnetic field, and the proton moves in a circle of radius 0.20 m. What is the
magnitude of the magnetic field?
A) 0.32 T
B) 0.24 T
C) 0.080 T
D) 0.16 T
29. An electric current produces
A) a gravitational field.
C) an electromagnetic field.
B) a magnetic field.
D) an electric field.
30. The SI unit of magnetic field is the
A) gauss.
B) weber.
C) lorentz.
D) tesla.
31. A horizontal rod (oriented in the east-west direction) is moved northward at
constant velocity through a magnetic field that points straight down. Make a
statement concerning the voltage induced across the rod (Recall current flows
toward lower potential).
A) The east end of the rod is at higher voltage than the west end.
B) The top surface of the rod is at higher voltage than the bottom surface.
Ph 203 Final Exam
Lane Community College – Spring 2005
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C) The bottom surface of the rod is at higher voltage than the top surface.
D) The west end of the rod is at higher voltage than the east end.
32. A circular coil lies flat on a horizontal table. A bar magnet is held above its center
with its north pole pointing down. The stationary magnet induces (when viewed
from above)
A) a counterclockwise current in the coil.
B) no current in the coil.
C) a clockwise current in the coil.
D) a current whose direction cannot be determined from the information given.
33. A circular loop of radius 0.10 m is rotating in a uniform magnetic field of 0.20T.
Find the magnetic flux through the loop when the plane of the loop and the
magnetic field vector are perpendicular.
A) 3.1 × 10-3 T∙m2
B) zero
C) 6.3 × 10-3 T∙m2
D) 5.5 × 10-3 T∙m2
34. A series RL circuit with inductance L and resistance R is connected to an emf V.
After a period of time, the current reaches a final value of 2.0 A. A second series
circuit is identical except that the inductance is 2L. When it is connected to the
same emf V, what will be the final value of the current?
A) 0.50 A
B) 4.0 A
C) 2.0 A
D) 1.0 A
35. A resistor and an inductor are connected in series to an ideal battery of constant
terminal voltage. At the moment contact is made with the battery, the voltage
across the inductor is
A) zero.
B) equal to the battery's terminal voltage.
C) greater than the battery's terminal voltage.
D) less than the battery's terminal voltage, but not zero.
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Lane Community College – Spring 2005
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Part II – Questions and Problems
Please explain or show your work clearly and completely for each of the following
questions or problem. Place your answers on the color sheets provided.
36. For the circuit shown at right
Label the currents and apply the
junction rule for the currents.
B) Apply the loop rule for each loop.
C) Determine the current in the 8-Ω
resistor.
A)
37. The following three appliances are connected to a 120-V circuit: 1200-W toaster,
650-W coffee pot, and 600-W microwave. If all were operated at the same time
what total current would they draw?
38. A square coil of wire with 15 turns and an area of 0.40 m2 is placed parallel to a
magnetic field of 0.75 T. The coil is flipped so its plane is perpendicular to the
magnetic field in 0.050 s. Determine
A) magnetic flux through the loop when it is parallel to B-field.
B) magnetic flux through the loop when it is perpendicular to B-field.
C) the magnitude of the average induced emf.
39. A foam ball of mass 0.150 g carries a charge of -2.00 nC. The ball is placed inside
a uniform electric field, and is suspended against the force of gravity.
A) Draw a free body diagram showing all forces acting on the ball?
B) What are the magnitude and direction of the electric field?
40. A conducting bar moves along frictionless conducting rails connected to a 4.00Ω
resistor as shown in the figure below. The length of the bar is 1.60 m and a
uniform magnetic field of 2.20 T is applied perpendicular to the paper. An applied
force moves the bar to the right with a constant speed of 6.00 m/s. At what rate is
energy dissipated in the 4.00 Ω resistor?
Bonus Question:
41. A 1.5-H inductor is connected in series with a 200-Ω resistor through a 15-V dc
power supply and a switch. If the switch is closed at t = 0 s, what is the maximum
Ph 203 Final Exam
Lane Community College – Spring 2005
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energy stored in the inductor?
Answers to ph203 final exam – early version (Does not Final exam final version)
1) C
2) C
3) C
4) A
5) D
6) B
7) B
8) C
9) C
10) C
11) A
12) B
13) B
14) B
15) B
16) A
17) B
18) A
19) A
20) B
21) D
Ph 203 Final Exam
Lane Community College – Spring 2005
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22) C
23) D
24) D
25) D
26) C
27) A
28) A
29) B
30) D
31) B
32) D
33) D
34) B
35) C
36) C
37) B
38) C
39) A
40) D
41) A
42) C
43) B
44) C
Ph 203 Final Exam
Lane Community College – Spring 2005
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