1. College Physics Chapter 18 Alan Giambattista Betty Richardson
Robert Richardson
4th edition
Chapter 18
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. Question 1
In the circuit shown, the current flows counterclockwise (CCW). This means
A) the electrons flow CCW.
B) the electrons flow CW.
C) the protons flow CCW.
D) the protons flow CW.

3. Question 2
A wire of length L and cross sectional area A has a resistance R. What would be the
resistance of two identical wires placed end-to-end?
A) 1/4 R
B) 1/2 R
C) R
D) 2R
E) 4R

4. Question 3
A wire of length L and cross sectional area A has a resistance R. What would be the
resistance of two identical wires in parallel?
A) 1/4 R
B) 1/2 R
C) R
D) 2R
E) 4R

5. Question 4
A wire of length L and diameter D has a resistance R. What would be the
resistance of a wire with length L and diameter 2D?
A) 1/4 R
B) 1/2 R
C) R
D) 2R
E) 4R

6. Question 5
A current I flows through a resistor R that is held at a constant potential V. If the
resistance is doubled, the new current is _____.
A) I/2
B) I
C) 2I

7. Question 6
Given the circuit below, what can you say about the current flowing into points A, B, C, and D?
A) IA > IB > IC > ID
B) IA = ID > IB = IC
C) IA < IB < IC < ID
D) IA = IB = IC = ID

8. Question 7
Given the circuit below, what can you say about the voltage measured at points A, B, C, and D?
A) VA > VB > VC > VD
B) VA = VB = VC = VD
C) VA = VB > VC = VD
D) VA < VB < VC < VD

9. Question 8
A circuit consists of three resistors connected in parallel across a potential V. If R1 > R2 >
R3, which of the following is a true statement about the current flowing through each resistor?
A) I1 > I2 > I3
B) I1 = I2 = I3
C) I1 < I2 < I3
D) Cannot be determined.

10. Question 9
A circuit consists of three resistors connected in series across a potential V. If R1 > R2 > R3, which of the following is a true statement about the current flowing through each resistor?
A) I1 > I2 > I3
B) I1 = I2 = I3
C) I1 < I2 < I3
D) Cannot be determined.

11. Question 10
Your portable radio requires an emf of 24 V. You have a box of 6 V batteries. To attain the required emf, you should
A) connect two batteries in series to two batteries in parallel.
B) connect three batteries in parallel in series with a fourth battery.
C) connect four batteries in parallel.
D) connect four batteries in series.

12. Question 11
The electric company wants to send power to a remote substation and must connect several power lines to reach it. To reduce power losses in the wire, the electric company
should
A) use a very high voltage and low current.
B) use a low voltage and very high current.
C) not worry about the voltage or current as the power loss will be the same.

13. Question 12
In the circuit shown below, two capacitors in parallel are connected to a battery through a resistor. Initially the switch is open. When the switch is closed, the current through the resistor is
A) at a maximum
and decreasing.
B) at a minimum
and increasing.
C) at a minimum and decreasing.
D) at a maximum and increasing.

14. Question 13
In this circuit, two capacitors in parallel are connected to a battery through a resistor.
Initially the switch is open. A long time after the switch is closed, the current through the
resistor is
A) 12.5 A
B) 12.5 mA
C) 0
D) 80 A

15. Question 14
Rank the drift velocity of the electrons in each of the following copper wires (each has the same potential difference across the ends). 3 4 L 2L L 2L 1 2 A 2A A 2A
v2 > v1 = v4 > v3
C) v2 = v1 > v4 = v3
B) v3 > v4 = v1 > v2
D) not enough information

16. Question 15
How much work is done by a 12.0-V ideal battery that supplies a 5.00-A current for 30.0 minutes?
A) 1800 J
B) 1.08 x 105 J
C) 4320 J
D) 750 J

17. Question 16 As the temperature increases, the resistance of a resistor
A) decreases because the electrons are more mobile and have greater velocities.
B) increases because electrons collide more frequently, slowing their drift velocity.
C) is unchanged since temperature doesn't affect the number of charge-carrying electrons.

18. Question 17
A copper wire is an Ohmic resistor. The resistance is given by the slope of the in in which of the following graphs? I I I I DV DV DV DV A B C D

19. Question 18
Two 12-Ω resistors are connected in series. The equivalent resistance is
A) less than 12 Ω.
B) equal to 12 Ω.
C) greater than 12 Ω.

20. Question 19
Two 12-Ω resistors are connected in parallel. The equivalent resistance is
A) less than 12 Ω.
B) equal to 12 Ω.
C) greater than 12 Ω.

21. Question 20
You are designing the wiring for your new house. You would like for a single switch to turn on three floodlights. To get the greatest illumination, you should wire the lights in the circuit in
A) series.
B) parallel.
C) it won't matter since the bulbs are a fixed wattage.

22. Answer Key – Chapter 18 B D A C A C B D