Exam
Name___________________________________
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false.
1) Magnetic field lines come out of the south pole of a magnet and enter at the north pole.
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
2) Which of the following statements is correct?
A) Earth's north pole is magnetic north.
B) The north pole of a magnet points towards the Earth's north pole.
C) Like poles of a magnet attract each other and unlike poles repel.
D) The SI unit of the magnetic field is the gauss.
3) A +2-mC charge is at rest in a magnetic field of 2 T pointing along the +x-axis. What is the force acting on this
charge in the magnetic field?
A) +4 mN
B) 0 N
C) -4 mN
D) +2 mN
4) An electron moving along the +x-axis enters a magnetic field. If the electron experiences a magnetic deflection
in the -y direction, what is the direction of the magnetic field in this region?
A) along the +z-axis
C) along the -x-axis
B) along the +y-axis
D) along the -z-axis
5) A charged particle moving with a certain velocity along the +x-axis enters a magnetic field pointing toward the
+z-axis. Determine the required direction of an electric field that will allow the charged particle to continue to
move along the +x-axis.
A) along the -x-axis
C) along the +y-axis
B) along the -y-axis
D) along the +x-axis
Figure 22-2
6) A rectangular coil, with corners labeled ABCD, of length L and width w is placed in a magnetic field B as shown
in Figure 22-2. If there is a current I flowing through this coil, what is the force acting on section AB of this coil?
A) ILB
C) 0 N
B) ILB sinq
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D) ILB/2
7) A wire is carrying current vertically downward. What is the direction of the force due to Earth's magnetic field
on the wire?
A) horizontally towards the east
B) horizontally towards the south
C) horizontally towards the west
D) horizontally towards the north
Figure 22-3
8) A wire in the shape of an "M" lies in the plane of the paper. It carries a current of 2.0 A, flowing from A to E. It
is placed in a uniform magnetic field of 0.55 T in the same plane, directed as shown on the right side of Figure
22-3. The figure indicates the dimensions of the wire. What is the magnitude and direction of the force acting
on section AB of this wire?
A) 0.20 N perpendicular into the page
B) 0.080 N perpendicular out of the page
C) 0.20 N perpendicular out of the page
D) 0.080 N perpendicular into the page
Figure 22-4
9) A rectangular loop of wire, with dimensions as shown in Figure 22-4, carrying a 2-A current is placed in a
magnetic field of 0.8 T. The loop rotates in the magnetic field and at one point makes a 30e angle with the
magnetic field. What is the magnitude of the torque acting on the wire?
A) 0.5 Nm
B) 0.4 Nm
C) 0.6 Nm
D) 0.3 Nm
10) A solenoid of 200 turns carrying a current of 2 A has a length of 25 cm. What is the magnitude of the magnetic
field at the center of the solenoid?
A) 5 mT
B) 3 mT
C) 4 mT
2
D) 2 mT
Figure 22-6
11) Three particles travel through a region of space where the magnetic field is out of the page, as shown in Figure
22-6. The electric charge of each of the three particles is, respectively,
A) 1 is neutral, 2 is negative, and 3 is positive.
B) 1 is negative, 2 is neutral, and 3 is positive.
C) 1 is positive, 2 is negative, and 3 is neutral.
D) 1 is positive, 2 is neutral, and 3 is negative.
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false.
12) An emf is induced in a wire by moving the wire near a magnet.
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
Figure 23-1
13) A cube whose edges are 0.10 m long has one corner at the origin of an xyz-coordinate system as shown in
Figure 23-1. A magnetic field with a strength of 0.40 T is applied along the +x-axis. What is the magnetic flux
through the shaded face of the cube?
A) 4.0 ˛ 10-4 Tœm2
B) 4.0 ˛ 10-3 Tœm2
C) 4.0 ˛ 10-2 Tœm2
D) 4.0 ˛ 10-1 Tœm2
14) The area of a rectangular loop of wire is 3.4 ˛ 10-3 m2. The loop is placed in a magnetic field that changes from
0.20 T to 1.2 T in 1.6 s. The plane of the loop is perpendicular to the direction of the magnetic field. What is the
magnitude of the induced emf in that loop?
A) 1.8 ˛ 10-3 V
B) 2.8 ˛ 10-3 V
C) 0 V
D) 2.1 ˛ 10-3 V
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TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false.
15) The negative sign in the Faraday's equation for electromagnetic induction is related to the direction of the
induced emf.
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
Figure 23-3
16) A bar magnet is placed with its north pole pointing toward a coil of wire that has a cross-sectional area of 0.02
m2 and 6 turns, as shown in Figure 23-3(a). What is the magnitude of the induced emf in the coil of wire?
A) 0.02 V
B) 0.04 V
C) 0.01 V
D) 0 V
Figure 23-5
17) A conducting rod whose length is 25 cm is placed on a U-shaped metal wire that has a resistance R of 8 W as
shown in Figure 23-5. The wire and the rod are in the plane of the paper. A constant magnetic field of strength
0.4 T is applied perpendicular and into the paper. An applied force moves the rod to the right with a constant
speed of 6 m/s. What is the magnitude of the induced emf in the wire?
A) 0.5 V
B) 0.6 V
C) 0.2 V
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D) 0.4 V
Figure 23-9
18) A rectangular coil of N turns, length L = 25 cm, and width w = 15 cm, as shown in Figure 23-9, is rotating in a
magnetic field of 1.6 T with a frequency of 75 Hz. If the coil develops a sinusoidal emf of maximum value 56.9
V, what is the value of N?
A) 8
B) 6
C) 4
D) 2
19) Which one of the following is the correct expression for the time constant of an RL circuit?
A) R/L
B) LR
C) L/R
D) None of the other answers is correct.
20) The primary coil of a transformer has 100 turns and its secondary coil has 400 turns. If the ac current in the
secondary coil is 2 A, what is the current in its primary coil?
A) 4 A
B) 8 A
C) 1/2 A
D) 2 A
Figure 23-11
21) The two identical bar magnets in Figure 23-11 are dropped from rest along a vertical line passing through the
center of the rings, as shown. The two rings are identical in every respect except that the ring on the right has a
small break in it. Calling aL and aR the magnitude of the downward accelerations of the magnets on the left
and right, respectively, you observe that
A) aL < aR.
B) aL = aR.
C) aL > aR.
D) It is not possible to predict the outcome of this experiment with the data given.
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false.
22) An ac signal of a certain frequency is applied to a capacitor. The current leads the voltage by 90e .
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MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
23) A total impedance of an RC circuit with a capacitance of 25.0 mF is 800 W. If the frequency of the applied ac
voltage is 12.0 Hz, what is the resistance of the circuit?
A) 399 W
B) 699 W
C) 599 W
D) 499 W
24) What is the inductive reactance of a 20-mH inductor at a frequency of 60 Hz?
A) 7.5 mW
B) 0.13 W
C) 7.5 W
D) 12 ˛ 10-1 W
25) A certain ac signal at 1000 Hz is applied across an inductor and a 100-W resistor. If the power factor of the
circuit is 0.400, what is the impedance of this circuit?
A) 250 W
B) 200 W
C) 150 W
D) 100 W
26) The phase angle of a series RL circuit with a 20.0-mH inductor and a certain resistor at 1000 Hz is 20.0e. What is
the value of the resistance in this circuit?
A) 100 W
B) 245 W
C) 345 W
D) 200 W
Figure 24-2
27) The figure shows a simple ac circuit composed of a capacitor connected across the terminals of an ac generator.
If the frequency of the generator is doubled, what happens to the capacitive reactance of the capacitor?
A) It decreases by a factor of 2.
B) It increases by a factor of 2.
C) It increases by a factor of 4.
D) It decreases by a factor of 4.
28) What is the power factor of an RLC series circuit with an inductive reactance of 174 W, a capacitive reactance of
60 W and a resistance of 100 W?
A) 0.76
B) 0.66
C) 0.46
D) 0.56
29) A 120-V rms voltage at 1000 Hz is applied to an inductor, a 2.00-mF capacitor and a 100-W resistor. If the rms
value of the current in this circuit is 0.680 A, what is the value of the inductor?
A) 11.4 mH
B) 22.8 mH
C) 35.8 mH
D) 34.2 mH
30) A series RLC circuit has a 300-W resistor, a 12.0-mH inductor and a 0.500-mF capacitor connected across a
120-V rms ac source at 30.0 kHz. What is the phase angle of the circuit?
A) 0e
B) 47.3e
C) 90.0e
D) 82.4e
31) In a RLC circuit, the values of the inductance and capacitance are both doubled. In comparison with the
resonance frequency of the original circuit, the new resonant frequency will be
A) reduced to one-quarter the original value.
B) increased by a factor of two.
C) reduced to one-half the original value.
D) the same as before.
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32) The energy stored in a coil of self-inductance, L, and traversed by current I, is E1. A second coil is made with
the same length of wire, but its radius is twice the radius of the first coil and it is twice as long as the first coil. If
the second coil also has twice the current of the first coil, how does the energy stored in the first coil, E1,
compare to the energy stored in the second coil, E2?
A) E1 = 2 E2
B) E1 = E2
C) E1 = E2/2
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D) E1 = 4 E2
Answer Key
Testname: EXAM2.TST
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false.
1) FALSE
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
2) B
3) B
4) D
5) C
6) A
7) A
8) B
9) A
10) D
11) B
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false.
12) TRUE
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
13) B
14) D
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false.
15) TRUE
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
16) D
17) B
18) D
19) C
20) B
21) A
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false.
22) TRUE
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
23)
24)
25)
26)
27)
28)
29)
30)
31)
32)
C
C
A
C
A
B
C
D
C
A
1