ch 18 practice
Multiple Choice
Identify the choice that best completes the statement or answers the question.
1. Which of the following is the best description of a
5. If the potential difference across a pair of batteries used
schematic diagram?
to power a flashlight is 6.0 V, what is the potential
a. uses pictures to represent the parts of a circuit
difference across the flashlight bulb?
b. determines the location of the parts of a circuit
a. 3.0 V
c. shows the parts of a circuit and how the parts
b. 6.0 V
connect to each other
c. 9.0 V
d. shows some of the parts that make up a circuit
d. 12 V
6. If the batteries in a portable CD player provide a
2.
terminal voltage of 12 V, what is the potential difference
across the entire CD player?
a. 3.0 V
b. 4.0 V
c. 6.0 V
d. 12 V
7. How does the potential difference across the bulb in a
flashlight compare with the terminal voltage of the
batteries used to power the flashlight?
a. The potential difference is greater than the terminal
voltage.
b. The potential difference is less than the terminal
voltage.
c. The potential difference is equal to the terminal
voltage.
What happens when the switch is closed in the circuit
d. It cannot be determined unless the internal
shown above?
resistance of the batteries is known.
a. The lamp lights because current from the battery
8.
If
a
9.0
V battery is connected to a lightbulb, what is the
flows through the lamp.
potential
difference across the bulb?
b. Current from the battery is carried through the
a.
3.0
V
resistor.
b. 4.5 V
c. Current from the battery is carried through both the
c. 9.0 V
lamp and the resistor.
d. 18 V
d. The lamp goes out, because the battery terminals
9.
Which of the following statements about a battery as a
connect to each other.
source of electric current is not true?
3. A circuit has a continuous path through which charge
a. A battery is a source of emf.
can flow from a voltage source to a device that uses
b. A battery provides the energy that moves charge.
electrical energy. What is the name of this type of
c. The terminal voltage of a battery is equal to its emf.
circuit?
d. The terminal voltage of a battery is the voltage it
a. a short circuit
delivers to the load.
b. a closed circuit
10. Three resistors with values of 4.0 , 6.0 , and 8.0 ,
c. an open circuit
respectively, are connected in series. What is their
d. a circuit schematic
equivalent resistance?
4. If the potential difference across the bulb in a camping
a. 18 
lantern is 9.0 V, what is the potential difference across
b. 8.0 
the battery used to power it?
c. 6.0 
a. 1.0 V
d. 1.8 
b. 3.0 V
c. 9.0 V
11. Three resistors connected in series carry currents labeled
d. 18 V
I , I , and I , respectively. Which of the following
expresses the total current, I , in the system made up of
the three resistors in series?
a.
b.
It = I1 + I2 + I3
It =
c.
d.
It = I1 = I2 = I3
16. Three resistors connected in parallel carry currents
labeled I , I , and I . Which of the following expresses
the total current I in the combined system?
a. It = I1 + I2 + I3
b.
It =
It =
12. Three resistors connected in series have potential
differences across them labeled V , V , and V .
Which of the following expresses the potential
difference taken over the three resistors together?
a. Vt = V1 + V2 + V3
b.
Vt =
c.
d.
Vt = V1 = V2 = V3
c.
d.
It = I1 = I2 = I3
It =
17. Three resistors connected in parallel have potential
differences across them labeled V , V , and V .
Which of the following expresses the potential
difference across all three resistors?
a. Vt = V1 + V2 + V3
b.
Vt =
Vt =
13. Three resistors with values of R , R , and R are
connected in series. Which of the following expresses
the total resistance, R , of the three resistors?
a.
b.
Req = R1 + R2 + R3
Req =
c.
d.
Req = R1 = R2 = R3
c.
d.
Vt = V1 = V2 = V3
Vt =
18. Three resistors with values of R , R , and R are
connected in parallel. Which of the following expresses
the total resistance, R , of the three resistors?
a.
b.
Req = R1 + R2 + R3
Req =
Req =
14. A circuit is composed of resistors wired in series. What
is the relationship between the equivalent resistance of
the circuit and the resistance of the individual resistors?
a. The equivalent resistance is equal to the largest
resistance in the circuit.
b. The equivalent resistance is greater than the sum of
all the resistances in the circuit.
c. The equivalent resistance is equal to the sum of the
individual resistances.
d. The equivalent resistance is less than the smallest
resistance in the circuit.
15. Three resistors with values of 3.0 , 6.0 , and 12  are
connected in series. What is the equivalent resistance of
this combination?
a. 0.58 
b. 1.7 
c. 7.0 
d. 21 
c.
d.
Req = R1 = R2 = R3
Req =
19. Two resistors having the same resistance value are wired
in parallel. How does the equivalent resistance compare
to the resistance value of a single resistor?
a. The equivalent resistance is twice the value of a
single resistor.
b. The equivalent resistance is the same as a single
resistor.
c. The equivalent resistance is half the value of a
single resistor.
d. The equivalent resistance is greater than that of a
single resistor.
20. Three resistors with values of 4.0 , 6.0 , and 10.0 
are connected in parallel. What is their equivalent
resistance?
a. 20.0 
b. 7.3 
c. 6.0 
1.9 
21. Three resistors with values of 3.0 , 6.0 , and 12  are
connected in parallel. What is the equivalent resistance
of this combination?
a. 0.26 
b. 1.7 
c. 9.0 
d. 21 
22. The equivalent resistance of a complex circuit is usually
determined by
a. inspection.
simplifying the circuit into groups of series and
parallel circuits.
c. adding and subtracting individual resistances.
d. dividing the sum of the individual resistances by the
number of resistances.
23. To find the current in a complex circuit, it is necessary to
know the
a. potential difference in each device in the circuit.
b. current in each device in the circuit.
c. equivalent resistance of the circuit.
d. number of branches in the circuit.
24. What is the equivalent resistance of the resistors in the
figure shown above?
a. 7.5 
b. 10 
c. 16 
d. 18 
25. Two resistors with values of 6.0  and 12  are
connected in parallel. This combination is connected in
series with a 4.0  resistor. What is the equivalent
resistance of this combination?
a. 0.50 
b. 2.0 
c. 8.0 
d. 22 
d.
b.
26. What is the equivalent resistance for the resistors in the figure shown above?
a. 25 
c. 7.5 
b. 10.0 
d. 5.0 
27. What is the equivalent resistance for the resistors in the figure shown above?
a. 1.3 
c. 3.0 
b. 2.2 
d. 12.0 
28. Three resistors connected in parallel have individual
values of 4.0 , 6.0 , and 10.0 , as shown above. If
this combination is connected in series with a 12.0 V
battery and a 2.0  resistor, what is the current in the
10.0  resistor?
a. 0.58 A
b. 1.0 A
c. 11 A
d. 16 A
29. Two resistors with values of 6.0  and 12  are
connected in parallel. This combination is connected in
series with a 2.0  resistor and a 24 V battery. What is
the current in the 2.0  resistor?
Problem
31. Three resistors with values of 29 , 56 , 24 ,
respectively, are connected in series. What is their
equivalent resistance?
a. 2.0 A
b. 4.0 A
c. 6.0 A
d. 12 A
30. In any complex resistance circuit, the voltage across any
resistor in the circuit is always
a. less than the voltage source.
b. equal to or less than the voltage source.
c. equal to the voltage source.
d. greater than the voltage source.
34. Three resistors are wired in series with a 28.5 V battery.
The resistances are 21.2 , 37.6 , and 6.1 . What is
the voltage across the 6.1  resistor?
32. Three resistors with values of 69 , 176 , 98 ,
respectively, are connected in series. What is their
equivalent resistance?
35. Three resistors with values of 23 , 89 , 19 ,
respectively, are connected in parallel. What is their
equivalent resistance?
33. A current of 0.12 A passes through a 5.1  resistor. The
resistor is connected in series with a 9.1 V battery and an
unknown resistor. What is the resistance value of the
unknown resistor?
36. Three resistors with values of 4.8 , 5.3 , 12.7 ,
respectively, are connected in parallel. What is their
equivalent resistance?
37. How much current is in one of the 10  resistors in the diagram shown above?
38. Two resistors having values of 4.1  and 5.8  are wired in parallel. This pair of resistors is wired in series with a second pair
of parallel resistors having values of 4.7  and 5.9 . If the current in the 5.8  resistor is 0.35 A, what is the voltage across
the entire circuit?