True/False
Indicate whether the
statement is true or false.
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1.
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The total resistance of four
resistors in parallel is always less than the smallest resistance.
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2.
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If IR1 = 0.065 mA and IR2 =
0.098 mA in a two branch parallel circuit, IT = 0.163 mA.
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3.
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If one branch of a parallel
circuit opens, the total resistance decreases.
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4.
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Kirchhoff's Current Law
states that the sum of the currents into a junction must equal the sum of the currents out of that
junction.
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5.
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The total resistance of three
parallel resistors equals the sum of the individual resistor values.
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6.
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A parallel circuit can be
easily identified because only one end of each component is connected to each
other.
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7.
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Accurate troubleshooting of a
parallel circuit cannot be performed with a voltmeter.
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Multiple Choice
Identify the
choice that best completes the statement or answers the question.
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8.
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If a 5.5 kÙ, 22 kÙ and 500 Ù
resistor are connected in parallel, what is RT?
a. | 330
Ù | c. | 449
Ù | b. | 28.1 kÙ | d. | 27.6
kÙ |
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9.
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If a 500 Ù, 1200 Ù and 10 kÙ
resistor are connected in parallel across a 25 V source, how much current flows through the 1200
Ù resistor?
a. | 2.4 mA | c. | 20.8 mA | b. | 2.5 mA | d. | 50 mA |
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10.
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If a 2.2 kÙ resistor and a 3.3 kÙ resistor are connected in
parallel, RT equals ________.
a. | 2.2
kÙ | c. | greater than 2.2
kÙ | b. | 3.3 kÙ | d. | less than 2.2
kÙ |
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11.
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In a three-resistor parallel
circuit, R1 = 0.22 MÙ and R2 = 1 MÙ.
If RT = 0.1166 MÙ, then what is the value of R3?
a. | 1.34 M
Ù | c. | 0.33 M
Ù | b. | 13,400 Ù | d. | 0.134 M
Ù |
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12.
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If a 1 MÙ resistor, 0.47 MÙ resistor and 0.5 MÙ resistor are connected in parallel across an 18 V source, what is the total current if
the 1 MÙ resistor opens?
a. | 92.3 ìA | c. | 74.3
ìA | b. | 74.3 mA | d. | 92.3 mA |
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13.
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If twelve 1.5
MÙ resistors are connected in parallel across 50 V, RT equals
________.
a. | 1.25
MÙ | c. | 1
MÙ | b. | 0.125 MÙ | d. | 1.5 M
Ù |
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14.
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IT equals 0.1 mA in a 3-branch
parallel circuit. If I1 = 0.022 mA and I2 = 0.007 mA, I3 = ?
a. | 0.071
mA | c. | 0.029
mA | b. | 0.213
mA | d. | 0.142 mA |
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15.
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If one resistor opens in a
parallel circuit, the total circuit resistance ________ and the total circuit current
________.
a. | decreases,
increases | c. | increases,
increases | b. | increases, decreases | d. | decreases, decreases |
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16.
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If three 22 kÙ resistors are connected in parallel across a 10 V source, PT equals
________.
a. | 22.6 m
W | c. | 4.5 m
W | b. | 18.1 m
W | d. | 13.6 m W |
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17.
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If one resistor shorts in a
parallel circuit, the total current ________.
a. | decreases | b. | increases | c. | equals 0 A | d. | decreases momentarily, then returns to the original
value |
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18.
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If four 100 W lamps are
connected in parallel across a 120 V source, what is the total current?
a. | 833 mA | c. | 33.3 A | b. | 8.33 A | d. | 3.33 A |
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19.
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If you measure a lower than
normal total current in a parallel circuit, ________.
a. | all of the resistors are
opened | c. | the power supply is
off | b. | a resistor opened | d. | a resistor shorted |
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20.
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A formula that applies to a
two-branch parallel circuit is ________.
a. | VT = VR1 +
VR2 | c. | IT = IR1 +
IR2 | b. | RT = R1 + R2 | d. | RT = V1 ÷ R2 |
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21.
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The current through any branch
of a parallel circuit ________.
a. | is directly proportional to the
branch resistance | b. | is inversely proportional to the branch
resistance | c. | depends on the power rating of the resistor | d. | depends only on the circuit
voltage |
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22.
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If you want to measure a load
voltage with a DVM, connect the meter ________.
a. | in series with the
source | c. | in series with the
load | b. | in parallel with the load | d. | across the source |
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23.
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The total resistance of a
three-branch parallel circuit is 76.92 Ù. If R1 = 100
Ù and R2 = 500 Ù, what is the value
of R3?
a. | 1000
Ù | b. | 140 Ù | c. | 1850 Ù | d. | More information is needed to calculate
R3. |
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24.
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A two-branch parallel circuit
contains these values: R1 = 1200 Ù, IT = 0.005 mA, I2 = 0.003 mA.
What is the value of VR1?
a. | 6 m V | c. | 18 m V | b. | 2.4 m V | d. | 3.6 m V |
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25.
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As additional branch resistors
are connected in a parallel circuit, ________.
a. | IT increases and RT
decreases | c. | IT increases and
RT increases | b. | IT decreases and RT increases | d. | IT decreases and RT decreases |
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26.
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If a 4.7 kÙ resistor, a 3.3 kÙ resistor and a 5.43
kÙ resistor are connected in parallel across a 50 V source, what is
the current through the 5.43 kÙ resistor?
a. | 10.64
mA | c. | 15.15
mA | b. | 9.21
mA | d. | 4.72 mA |
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27.
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RT = 330 Ù and R1 = 470 Ù in a two-branch parallel circuit. What
is the value of R2?
a. | 110
Ù | c. | 1108
Ù | b. | 770 Ù | d. | 194
Ù |
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28.
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If a 330 Ù resistor, 270 Ù resistor and 68 Ù resistor are connected in parallel, what is the approximate value for
RT?
a. | 47
Ù | c. | 22
Ù | b. | 68 Ù | d. | 668
Ù |
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29.
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If 5 A and 3 A enter a junction
from two separate paths, how much current flows out of the junction?
a. | 2 A | c. | 3 A | b. | 8 A | d. | the larger of the two |
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30.
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Each branch in a four-branch
parallel circuit carries 10 mA. If one of the branches opens, then the current in each of the other
three branches equals ________.
a. | 10 mA | c. | 13.33 mA | b. | 30 mA | d. | 0 A |
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31.
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If there is 100 mA of current
flowing into a three-branch parallel circuit and two of the branch currents are 40 mA and 20 mA, the
third branch current is ________.
a. | 160 mA | c. | 20 mA | b. | 60 mA | d. | 40 mA |
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32.
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If the power dissipation in
each of four parallel branches is 1 W, PT equals ________.
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33.
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If a 2.2 kÙ resistor, 10 kÙ resistor and 1.2 kÙ resistor are connected in parallel, the total resistance equals
________.
a. | 13.4
kÙ | c. | 2.27
kÙ | b. | 1.2 kÙ | d. | 721
Ù |
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34.
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If a 470 Ù resistor, 680 Ù resistor and 830 Ù resistor are connected in parallel, the total resistance equals
________.
a. | 1510
Ù | c. | 1980
Ù | b. | 208 Ù | d. | 1150
Ù |
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35.
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If a 4.7 kÙ resistor and 2.2 kÙ resistor are connected in
parallel, the total resistance is ________.
a. | 2200
Ù | c. | greater than 2200
Ù | b. | 4700 Ù | d. | less than 2200
Ù |
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36.
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In a three-branch parallel
circuit, R1 = 1.2 MÙ, R2 = 1 MÙ and
RT = 0.5 MÙ. Calculate R3.
a. | 6
MÙ | c. | 2
MÙ | b. | 7.7 MÙ | d. | 1.7
MÙ |
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37.
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A 5.2 MÙ resistor, 1.2 MÙ resistor and 1 MÙ resistor are connected in parallel across a 15 V source. What is the total current if
the 1.2 MÙ resistor opens?
a. | 2.88 ìA | c. | 2.41
ìA | b. | 12.5 ìA | d. | 17.9 ìA |
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38.
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If eight 47 kÙ resistors are connected in parallel across a 25 V source, RT equals
________.
a. | 5.88
kÙ | c. | 4.7
kÙ | b. | 376 kÙ | d. | 6.71
kÙ |
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39.
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A three-branch parallel circuit
carries a total current of 1.2 mA. If I1 = 0.2 mA and I2 = 0.7 mA, then what is the value of
I3?
a. | 2.4 mA | c. | 0.3 mA | b. | 8.7 mA | d. | 7.2 mA |
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40.
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If three 4.7
kÙ resistors are connected in parallel across a 12 V source, what is
the value of PT?
a. | 141 mW | c. | 14.1 mW | b. | 1.41 W | d. | 91.9 mW |
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41.
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If one resistor opens in a
parallel circuit, the total current ________.
a. | remains
unchanged | c. | increases | b. | varies wildly | d. | decreases |
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42.
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If three 75 W lamps are
connected in parallel across a 125 V source, IT equals ________.
a. | 18 mA | c. | 180 mA | b. | 1.8 A | d. | 18 A |
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43.
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If the total current equals 0 A
in a four-branch parallel circuit, the trouble is that ________.
a. | the power supply is
off | c. | one of the resistors has
shorted | b. | one resistor has opened | d. | three of the resistors have
opened |
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44.
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The power dissipated by any
branch of a parallel circuit ________.
a. | only depends on the total
current | b. | depends on the voltage and value of the
resistor | c. | only depends on the circuit voltage | d. | depends on the power rating of the
resistor |
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45.
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To measure the current through
one branch of a parallel circuit, the meter is connected ________.
a. | in series with the branch
resistor | c. | in series with the
source | b. | in parallel with the branch resistor | d. | across the source |
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46.
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If the RT = 6.8
kÙ and R1 = 10 kÙ in a two-branch
parallel circuit, what is the value of R2?
a. | 3.2
kÙ | c. | 21.3
kÙ | b. | 12 kÙ | d. | 16.8
kÙ |
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47.
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As resistors are disconnected
from a parallel circuit, ________.
a. | IT decreases and RT
increases | c. | IT increases and
RT decreases | b. | IT increases and RT increases | d. | IT decreases and RT decreases |
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48.
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The most popular application
for a parallel circuit in electronics is as a:
a. | power
divider. | c. | resistance
divider. | b. | current divider. | d. | voltage divider. |
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49.
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In a parallel circuit, total
power PT is calculated as:
a. | P1 × P2 × P3 ×
etc. | c. | P1 ÷ P2 ÷ P3 ÷
etc. | b. | P1 + P2 + P3 + etc. | d. | 1/P1 + 1/P2 + 1/P3 + etc. |
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50.
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In a parallel circuit, the
largest amount of power is dissipated by:
a. | the largest
resistor. | b. | the smallest resistor. | c. | the first resistor. | d. | any resistor, since the voltage is the same across each of
the branch circuits. |
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51.
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An open in one branch of a
parallel circuit results in:
a. | decreased power
consumption. | c. | decreased or
reduced current flow. | b. | increased circuit resistance. | d. | all of these. |
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52.
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A short in one branch of a
parallel circuit results in:
a. | decreased power
consumption. | b. | increased current flow. | c. | increased voltage drops in the remaining
branches. | d. | increased circuit resistance. |
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53.
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Refer to Figure 5-1. To
accurately measure the total current for this circuit, how must the ammeter be connected?
Figure 5-1
a. | between the negative terminal and
the supply and ground | b. | between R1 and the fuse | c. | between the positive terminal and the
fuse | d. | either A or C |
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54.
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Refer to Figure 5-1. What is
the power dissipation of R3?
Figure
5-1
a. | 25 mW | c. | 568 mW | b. | 11.4 mW | d. | 284 mW |
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