True/False Indicate whether the
statement is true or false.
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1.
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A fuse is an automatic switch that opens when the current reaches a threshold
value.
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2.
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To measure the potential drop across a resistor, a voltmeter is connected in
parallel with a resistor.
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3.
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Without a fuse or circuit breaker, the current caused by a short circuit easily
could start a fire.
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4.
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A ground-fault interrupter in an electric outlet prevents injuries because it
contains an electronic circuit that detects differences in current caused by an extra path and opens
the circuit.
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5.
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It is necessary to understand series and parallel circuits to fully understand
residential wiring.
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6.
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All household devices are connected in parallel because they are designed to
operate at the same voltage.
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7.
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A circuit breaker is a short piece of metal that melts when a current that is
too large passes through it.
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8.
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Fuses and circuit breakers protect against the large currents created by a short
circuit.
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9.
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Ammeters have a very high resistance so as to cause the smallest possible change
in currents and voltages in the circuit.
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Multiple Choice Identify the
choice that best completes the statement or answers the question.
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10.
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If a resistor is added to a series circuit, the equivalent resistance:
a. | increases | c. | remains the same | b. | decreases | d. | becomes zero |
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11.
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If a resistor is added to a parallel circuit, the equivalent resistance:
a. | increases | c. | remains the same | b. | decreases | d. | becomes zero |
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12.
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Ideally, the resistance of an ammeter should be:
a. | high | c. | more than 20 W | b. | medium | d. | zero |
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13.
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A/An _____ is described as an automatic switch that acts as a safeguard in an
electric current.
a. | circuit breaker | c. | ground fault interrupter | b. | fuse | d. | voltage divider |
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14.
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A parallel circuit has four branch currents: 120 mA, 380 mA, 250 mA, and 2.1
A. How much current is supplied by the source?
a. | .029 A | c. | 2.9 A | b. | 0.29 A | d. | 29 A |
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15.
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A/An _____ is described as a piece of metal that acts as a safety device in a
circuit which melts and stops the flow of current.
a. | circuit breaker | c. | ground fault interrupter | b. | fuse | d. | short
circuit |
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16.
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_____ is described as the sum of all the individual resistances in a
series.
a. | Equivalent resistance | c. | Series circuit | b. | Parallel circuit | d. | Short circuit |
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17.
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A/An _____ is described as a device that detects current differences and then
opens the circuit preventing electrocution.
a. | circuit breaker | c. | ground fault interrupter | b. | fuse | d. | short
circuit |
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18.
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A/An _____ is a device that is used to measure the current in any branch or part
of a circuit.
a. | ammeter | c. | resistor | b. | volt meter | d. | battery |
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19.
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A/An _____ occurs when a very low resistance circuit is formed and can easily
start a fire.
a. | parallel circuit | c. | short circuit | b. | series circuit | d. | voltage divider |
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20.
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A series circuit has four resistors. The current through one resistor is
810 mA. How much current is supplied by the source?
a. | .810 mA | c. | 81.0 mA | b. | 8.10 mA | d. | 810 mA |
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21.
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There are 11 lights in series, and they are in series with 2 lights in
parallel. If the 13 lights are identical, which of them will burn brightest?
a. | 11 lights | c. | all 13 lights | b. | 2 lights | d. | none will be
brightest |
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Matching
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Define the following terms by matching them to the correct
definition. a. | ammeter | f. | parallel
circuit | b. | circuit breaker | g. | series circuit | c. | equivalent resistance | h. | short circuit | d. | fuse | i. | voltage divider | e. | ground fault interrupter | j. | voltmeter |
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22.
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device used to measure voltage drop across any part of a circuit
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23.
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an automatic switch that acts as a safeguard in an electric current
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24.
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a low resistance device connected in series that is used to measure
current
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25.
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device that detects current differences; opens circuit preventing
electrocution
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26.
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a piece of metal that acts as a safety device in a circuit; melts and stops
flow
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Short Answer
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27.
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Compare and contrast the voltages and the currents in series and parallel
circuits.
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28.
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A 12 ohm, 2-W resistor is connected in parallel with a 6.0 ohm, 4-W
resistor. Which will become hotter if the voltage across them keeps increasing?
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29.
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Compare the voltage drop in a voltage divider to a volume control in a CD
player.
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Problem
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30.
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Three 20 ohm resistors are connected in series across a 120 V generator. What is
the equivalent resistance of the circuit? What is the current of the circuit?
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31.
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Three resistors, 60.0 ohms, 30.0 ohms, and 20.0 ohms, are connected in parallel
across a 90.0 V battery. a) Find the current through each branch of the circuit. b)
Find the equivalent resistance of the circuit. c) Find the current through the battery.
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32.
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Three 15.0 ohm resistors are connected in parallel across a 30.0 V
battery. a) Find the current through each branch of the circuit. b) Find the equivalent
resistance of the circuit. c) Find the current through the battery.
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33.
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A string of holiday lights has ten bulbs with equal resistances connected in a
series. When the string of lights is connected to a 120 V outlet, the current through the bulbs
is 0.06 A. What is the equivalent resistance of the circuit? What is the resistance of
each bulb?
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34.
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Three resistors, 120.0 ohms, 60.0 ohms, and 40.0 ohms are connected in a
parallel across a 120.0 V battery. a) Find the equivalent resistance of the circuit. b)
Find the current through the entire circuit. c) Find the current through each branch of the entire
circuit.
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35.
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Four resistors, 50.0 ohms, 40.0 ohms, 30.0 ohms, and 20.0 ohms, are connected in
a parallel across a 120.0 V battery. a) Find the current through each branch of the
circuit. b) Find the equivalent resistance of the circuit. c) Find the current through the
battery.
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