Download SPH3U1: ELECTRICITY AND MAGNETISM TEST Answer Section

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SPH3U1: ELECTRICITY AND MAGNETISM TEST
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____
1. An electrically neutral pith ball gains 4.0  1023 electrons. Its charge is now
a. –2.5  104 C
d. –4.0  1023 C
b. +1.6  10–19 C
e. –1.4  10–18 C
4
c. –6.4  10 C
____
2. How many electrons must be transferred to a neutral pith ball to give it a charge of –8.0  10–16 C?
a. 8.0  1016
d. 8.0  103
b. 5.0  10 2
e. 2.0  10 4
3
c. 5.0  10
____
3. The SI unit for measuring charge is the
a. coulomb
b. ampere
c. volt
d. joule
e. watt
4. One ampere is equal to one
a. N/s
b. C/s
c. s/C
d. V/C
e. V/s
____
____
5. If 2.75  1019 electrons pass a point in a circuit in 30 s, the current is
a. 52 A
d. 0.15 A
b. 9.2 A
e. 1.3  102 A
c. 4.4 A
____
6. How many seconds will it take for 10.0 C of charge to pass through a 12.0 A circuit?
a. 120 s
d. 100 s
b. 0.120 s
e. 1.20 s
c. 0.833 s
____
7. Which of these units is equal to one volt ?
a. 1 J/s
b. 1 J/C
c. 1 C/s
d. 1 C/J
e. 1 J/C·s
____
8. When a current of 4.0 A travels in a conductor for 15 s at a voltage of 12 V, the energy transferred is
a. 3.2 J
d. 0.31 J
b. 5.0 J
e. 7.2102J
c. 45 J
____
9. Which device would most likely be classified as a load in an electrical circuit?
a. battery
d. cell
b. light bulb
e. none of the above
c. ammeter
____ 10. In what type of circuit do electrons follow one path from the source, to a load, and back to the source?
a. short circuit
d. series circuit
b. open circuit
e. connected circuit
c. parallel circuit
____ 11. The value of V2 in the following circuit is
a. 40 V
b. 35 V
c. 25 V
d. 15 V
e. 10 V
____ 12. Assuming the two resistors are identical, the value of I3 in the following circuit is
a. 10 A
b. 5.0 A
c. 7.5 A
d. 3.3 A
e. 1.0 A
____ 13. The opposition to the flow of electrons in a circuit is called the
a. current
d. charge
b. potential difference
e. work
c. resistance
____ 14. A circuit has a 120-V source. If the current is 10.0 A, the resistance in the circuit must be
a. 10.0 
d. 1.20  102 
–2
b. 8.33  10 
e. 12.0 
c. 1.20  103 
____ 15. If the voltage in a circuit is doubled and the resistance is halved, the current will be
a. increased by a factor of 2
d. decreased by a factor of 4
b. decreased by a factor of 2
e. unaffected
c. increased by a factor of 4
____ 16. A toy train set has a resistance of 20.0  and uses a current of 250 mA. If it ran for
one hour, what is the power of the train?
a. 1.2 W
d. 2.2  102 W
b. 5.0 W
e. 4.5  103 W
c. 75 W
____ 17. A fuse is rated at 15.0 A. If it is part of a 120-V circuit, which of the following could be connected without
blowing the fuse?
a. 200-W mixer
d. any of the above, individually
b. 800-W toaster
e. none of the above
c. 1000-W hair dryer
____ 18. Three 10.0-resistors are connected in parallel to one another in a 12.0-A circuit. The total resistance in the
circuit is
a. 0.0333 
d. 20.0 
b. 0.300 
e. 30.0 
c. 3.33 
____ 19. An electric toaster draws 5.00 A from a 120-V outlet for 3.0 h. If electricity costs 9.90¢ per kilowatt hour, the
total cost would be
a. $0.18
d. $18.00
b. $1.80
e. $20.20
c. $6.00
____ 20. Two separate wires are placed side by side. When a current travels through them, they repel one another.
Which statement best explains this observation?
a. The wires have magnetic fields around them.
b. The currents are flowing in opposite directions.
c. Both currents are flowing in the same direction.
d. both A and C
e. both A and B
____ 21. The strength of the magnetic field of a coil may be increased by
a. increasing the current in the wire
b. wrapping it around an iron core
c. increasing the number of loops in the coil
d. all of the above
e. none of the above
____ 22. The diagram below shows a straight conductor between the poles of a permanent magnet. The direction of the
magnetic force on the wire will be
a. up
b. down
c. left
d. right
e. out of the page
____ 23. A coil is connected to a galvanometer. When a permanent magnet is held steady in the center of the coil, the
galvanometer will indicate
a. A steady current.
d. A decreasing current.
b. An alternating current.
e. No current.
c. An increasing current.
____ 24. The diagram below shows a bar magnet being moved away from a coil. The pole induced at the side closest to
the magnet will be a(n) ____-pole and the current will flow ____ at the front of the coil.
a. N, up
b. N, down
c. S, up
d. N, down
e. positive, down
____ 25. A step-down transformer changes
a. High potential difference to low potential difference.
b. AC current to DC current.
c. High current to low current.
d. High resistance to low resistance.
e. DC current to AC current.
____ 26. If a 15.0-A current is transmitted through a wire with a resistance of 20.0 , what is the power loss in the
wire?
a. 11.2 W
d. 6.00  102 W
b. 26.7 W
e. 4.50  103 W
2
c. 3.00  10 W
____ 27. For the following DC motor, in what direction will the loop spin?
a.
b.
c.
d.
The loop will spin counterclockwise.
The loop will not spin.
The loop will spin half way clockwise and then back counterclockwise.
The loop will spin clockwise.
____ 28. Which term describes a transformer that has fewer windings in the secondary circuit?
a. increasing
b. step-down
c. decreasing
d. step-up
____ 29. Which of the following describes the change in current from the primary circuit to the secondary circuit of a
step-up transformer?
a. The current in the secondary circuit is less than the current in the primary circuit.
b. The current in the secondary circuit is equal to the current in the primary circuit.
c. The current in the secondary circuit is greater than the current in the primary circuit.
d. none of the above
____ 30. What is the direction of rotation of the following AC generator. Explain your answer (3)
31. The open circles represent compasses. Label the polarity of the solenoid and show the directions of the
compass needles.(2)
32. Show the connections of the wires to the cell so that the indicated poles will be produced.
33. The diagram below shows a cross-section of a current-carrying loop between the poles of a permanent
magnet. In which direction will the coil turn? Justify your answer. (3 marks)
34. A galvanometer shows the direction that current is moving through a wire. The needed can deflect to the left
or right. A spring brings the needle to centre when there is no current flowing. The current flowing through
the wire is directed into a coil that runs around the needle. In the following diagram, the needle is deflecting
to the right. In which direction is the current moving in the coil? Justify your answer. (3 marks)
Problem
35. A 120-V circuit contains a load with a resistance of 15.0 . What resistance must be added in parallel with
the load to result in a current of 12.0 A in the circuit? (3 marks)
36. In Spain, the standard electric current has a potential difference of 220 V. In Canada, the standard voltage is
120 V.
(a) How much more current would flow through a Canadian hair dryer rated at 1750 Watts in Spain compared
to Canada? (2 marks)
(b) What consequence could the increased current have on the hair dryer? (1 mark)
37. Perform the following circuit analysis. (5 MARKS)
38. Perform the following circuit analysis. (3 MARKS)
I1 = _____________
V1 = _______________ V2 = ______________ V3 = ___________________
I2 = ______________
I3 = ______________
SPH3U1: ELECTRICITY AND MAGNETISM TEST
Answer Section
MULTIPLE CHOICE
1. ANS:
STA:
2. ANS:
STA:
3. ANS:
STA:
4. ANS:
STA:
5. ANS:
STA:
6. ANS:
STA:
7. ANS:
STA:
8. ANS:
STA:
9. ANS:
STA:
10. ANS:
STA:
11. ANS:
STA:
12. ANS:
STA:
13. ANS:
STA:
14. ANS:
STA:
15. ANS:
STA:
16. ANS:
STA:
17. ANS:
STA:
18. ANS:
STA:
19. ANS:
STA:
20. ANS:
STA:
21. ANS:
STA:
C
EM1.01
C
EM1.01
A
EM1.01
B
EM1.01
D
EM1.01
C
EM1.01
B
EM1.01
E
EM1.01
B
EM1.01
D
EM1.01
C
EM1.01
B
EM1.01
C
EM1.01
E
EM1.01
C
EM1.01
A
EM1.01
D
EM1.01
C
EM1.01
A
EM1.01
E
EM1.05
D
EM1.04
PTS: 1
REF: I
OBJ: 12.2
PTS: 1
REF: K/U
OBJ: 12.2
PTS: 1
REF: C
OBJ: 12.2
PTS: 1
REF: C
OBJ: 12.3
PTS: 1
REF: I
OBJ: 12.3
PTS: 1
REF: I
OBJ: 12.3
PTS: 1
REF: C
OBJ: 12.4
PTS: 1
REF: I
OBJ: 12.4
PTS: 1
REF: K/U
OBJ: 12.5
PTS: 1
REF: K/U
OBJ: 12.5
PTS: 1
REF: I
OBJ: 12.5
PTS: 1
REF: I
OBJ: 12.5
PTS: 1
REF: K/U
OBJ: 12.6
PTS: 1
REF: I
OBJ: 12.5
PTS: 1
REF: I
OBJ: 12.6
PTS: 1
REF: I
OBJ: 12.7
PTS: 1
REF: I
OBJ: 12.7
PTS: 1
REF: K/U
OBJ: 12.6
PTS: 1
REF: I
OBJ: 12.7
PTS: 1
REF: I
OBJ: 13.5
PTS: 1
REF: K/U
OBJ: 13.4
22. ANS:
STA:
23. ANS:
STA:
24. ANS:
STA:
25. ANS:
STA:
26. ANS:
STA:
27. ANS:
LOC:
28. ANS:
LOC:
29. ANS:
LOC:
B
EM1.06
E
EM1.07
C
EM1.07
A
EM1.07
E
EM1.09
D
F3.6
B
F2.1
A
F3.8
PTS: 1
REF: I
OBJ: 13.5
PTS: 1
REF: K/U
OBJ: 14.2
PTS: 1
REF: K/U
OBJ: 14.2
PTS: 1
REF: K/U
OBJ: 14.4
PTS: 1
REF: I
OBJ: 14.5
PTS:
MSC:
PTS:
MSC:
PTS:
MSC:
1
REF: T/I
Understanding
1
REF: K/U
Knowledge
1
REF: K/U
Knowledge
OBJ: 12.6 The Direct Current Motor
OBJ: 13.5 Transformers
OBJ: 13.5 Transformers
MATCHING
30. ANS: E
LOC: F3.5
PTS: 1
REF: T/I
MSC: Understanding
OBJ: 13.4 Electricity Generation
SHORT ANSWER
31. ANS:
Both compass needles will point to the left.
PTS: 1
REF: K/U
OBJ: 13.4
STA: EM1.05
32. ANS:
The wire on the left side should be connected to the negative terminal and the wire on the right should be
connected to the positive terminal.
PTS: 1
33. ANS:
counterclockwise
REF: K/U
OBJ: 13.4
STA: EM1.04
PTS: 1
REF: K/U
OBJ: 13.5
STA: EM1.06
34. ANS:
The external magnetic field points toward the right. Using the right-hand rule for the motor principle on the
right side of the galvanometer, your thumb points out of the page while your fingers point to the left and your
palm faces downward. There will be a downward force on the left. Similarly on the left side of the
galvanometer, your thumb will point into the page while your fingers point to the left, so there will be an
upward force on the left side of the galvanometer. The needle will move clockwise to the right.
PTS: 1
LOC: F3.5
PROBLEM
REF: T/I
OBJ: 12.5 The Motor Principle
MSC: Analysis and Application
35. ANS:
VT = 120 V
R1 = 10.0 
IT = 15.0 A
R2 = ?
An additional 30.0 of resistance is needed.
PTS: 1
36. ANS:
Vp = 220 V
Vs = 120 V
Ps = 1750 W
REF: I
Is = ?
I=?
(a)
The ratio must be 1.8 : 1 (Np : Ns).
(b)
OBJ: 12.6
STA: EM1.01
The hair dryer will use 14.6 A of current if connected to the transformer.
(c)
The hair dryer would initially operate at 27 A, but would quickly overheat and
stop.
PTS: 1
37. ANS:
PTS: 1
38. ANS:
jf;a
PTS: 1
REF: I
OBJ: 14.5
STA: EM1.09