Chapter 19 - 20 Practice Test
Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
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1. The current in an electron beam in a cathode-ray tube is 7.0 × 10–5 A. How much charge hits the screen in 5.0
s?
a. 2.8 × 103 C
c. 3.5 × 10–4 C
–23
d. 5.3 × 10–4 C
b. 5.6 × 10 C
2. A wire carries a steady current of 0.1 A over a period of 20 s. What total charge moves through the wire in
this time interval?
a. 200 C
c. 2 C
b. 20 C
d. 0.005 C
3. In alternating current, the motion of the charges
a. continuously changes in the forward and reverse directions.
b. is equal to the speed of light.
c. is greater than the speed of light.
d. in the direction of the electric field.
4. A flashlight bulb with a potential difference of 4.5 V across it has a resistance of 8.0 Ω. How much current is
in the bulb filament?
a. 3.7 A
c. 9.4 A
b. 1.8 A
d. 0.56 A
5. Which of the following does NOT affect a material's resistance?
a. length
c. temperature
b. the type of material
d. Ohm's law
6. Which of the following wires would have the GREATEST resistance?
a. an aluminum wire 10 cm in length and 3 cm in diameter
b. an aluminum wire 5 cm in length and 3 cm in diameter
c. an aluminum wire 10 cm in length and 5 cm in diameter
d. an aluminum wire 5 cm in length and 5 cm in diameter
7. The power ratings on light bulbs are measures of the
a. rate that they give off heat and light.
b. voltage they require.
c. density of the charge carriers.
d. amount of negative charge passing through them.
8. If a 75 W light bulb operates at a voltage of 120 V, what is the current in the bulb?
a. 0.63 A
c. 9.0 × 103 A
b. 1.6 A
d. 1.1 × 10–4 A
9. If a lamp has a resistance of 120 Ω when it operates at a power of 1.00 × 102 W, what is the potential
difference across the lamp?
a. 110 V
c. 130 V
b. 120 V
d. 220 V
10. An electric toaster requires 1100 W at 110 V. What is the resistance of the heating coil?
c. 1.0 × 101 Ω
a. 7.5 Ω
b. 9.0 Ω
d. 11 Ω
11. If the potential difference across the bulb in a camping lantern is 9.0 V, what is the potential difference across
the battery used to power it?
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a. 1.0 V
c. 9.0 V
b. 3.0 V
d. 18 V
If the batteries in a portable CD player provide a terminal voltage of 12 V, what is the potential difference
across the entire player?
a. 3.0 V
c. 6.0 V
b. 4.0 V
d. 12 V
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.
d. It cannot be determined unless the internal resistance of the batteries is known.
The following three appliances are connected in series to a 120 V house circuit: a toaster, 1200 W; a coffee
pot, 750 W; and a microwave, 6.0 × 102 W. If all were operated at the same time, what total current would
they draw?
a. 3 A
c. 10 A
b. 5 A
d. 21 A
Three resistors with values of 3.0 Ω, 6.0 Ω, and 12 Ω are connected in series. What is the equivalent
resistance of this combination?
c. 7.0 Ω
a. 0.58 Ω
b. 1.7 Ω
d. 21 Ω
Three resistors with values of 4.0 Ω, 6.0 Ω, and 10.0 Ω are connected in parallel. What is their equivalent
resistance?
a. 20.0 Ω
c. 6.0 Ω
b. 7.3 Ω
d. 1.9 Ω
____ 17. What is the equivalent resistance for the resistors in the figure above?
c. 3.0 Ω
a. 1.3 Ω
b. 2.3 Ω
d. 7.5 Ω
____ 18. Three resistors with values of R1, R2, and R3 are connected in parallel. Which of the following expresses the
total resistance, Rt, of the three resistors?
a. Rt = R1 + R2 + R3
c. Rt = R1 = R2 = R3
b. Rt = (1/R1 + 1/R2 + 1/R3)
d. Rt =(1/R1 + 1/R2 + 1/R3)–1
____ 19.
What is the equivalent resistance for the resistors in the figure above if R1 has a value of 4.0 Ω, R2 has a
value of 4.0 Ω, and R3 has a value of 8.0 Ω?
a. 1.6 Ω
c. 16 Ω
b. 3.0 Ω
d. 6.7 Ω
____ 20. What is the equivalent resistance for the resistors in the figure above?
a. 6.2 Ω
c. 12 Ω
b. 1.0 × 101 Ω
d. 52 Ω
____ 21.
Using the above circuit, which bulbs will have a current?
a. B & C
c. A
b. A, B, & C
d. none of the bulbs
____ 22.
Using the above circuit, which resistor has the greatest current?
a. R1
c. equal amount of current
b. R2
d. not enough information to calculate
____ 23.
Using the above circuit, which resistor will have the lesser voltage?
a. R1
c. equal amount of voltage
b. R2
d. not enough information to calculate
____ 24.
What type of electric current is shown in the figure above?
a. AC
c. not enough information to determine
b. DC
Problem
25. A bolt of lightning discharges 1.7 C in 3.3 × 10–4 s. What is the average current during the discharge?
Chapter 19 - 20 Practice Test
Answer Section
MULTIPLE CHOICE
1.
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24.
C
C
A
D
D
A
A
A
A
D
C
D
C
D
D
D
B
D
D
B
A
B
C
B
PROBLEM
25. 5.1 × 103 A