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Unit 3 review
Modified True/False
Indicate whether the statement is true or false. If false, change the identified word or phrase to make the statement true.
____
1. The easiest way to neutralize a conductive material is to use a process called grounding.
_________________________
____
2. The quantity of an electric charge is measured in coulombs. _________________________
____
3. Static electricity describes an electric charge that is stationary on the surface of a material.
_________________________
____
4. An object becomes charged if it contains unequal numbers of electrons and protons.
_________________________
____
5. It is possible to charge an electroscope without touching it. _________________________
____
6. The unit of measurement that refers to the quantity of charge passing through a point in a conducting wire per
unit of time is the coulomb. _________________________
The following diagram illustrates an electrochemical cell with an ammeter and a voltmeter connected in the
circuit.
____
7. In the diagram above, C represents the source for the electrical circuit. _________________________
____
8. In the circuit illustrated above, the conductor is labelled A. _________________________
____
9. In a circuit with three identical resistors in parallel, the sum of the currents through the three resistors is equal
to the total current through the circuit. _________________________
____ 10. The total resistance of a series circuit consisting of three resistors, each of which has a resistance of 3
. _________________________
Multiple Choice
Identify the choice that best completes the statement or answers the question.
, is 1
____ 11. When you rub different materials with wool or cotton and then hold the materials together, you can determine
a. the properties of electric charges.
b. the speed of movement of electrons.
c. the sizes of electromagnetic fields.
d. which materials have a magnetic field.
The following diagram illustrates the charge on three different objects, A, B, and C.
____ 12. In the illustration above, object A is
a. positively charged.
b. negatively charged.
c. neutral.
d. a semiconductor.
The following diagram illustrates a simple circuit.
____ 13. In the circuit illustrated above, the current flows
a. from the positive terminal of the battery through the circuit to the negative terminal.
b. from the negative terminal of the battery through the circuit to the positive terminal.
c. only when the switch is open.
d. Both B and C.
____ 14. The symbol I is used to represent
a. load.
b. current.
c. volts.
d. power.
____ 15. The following diagram illustrates a circuit that consists of a battery, a switch, and a lamp.
The battery has a voltage of 9 V and the lamp has a resistance of 6 . What is the current through the circuit?
a. 0.67 A
c. 1.5 A
b. 3 A
d. 72 A
____ 16. Which of the following graphs shows the relationship between potential difference (V) and current (I) through
a simple electrical circuit in which the resistance remains constant?
a.
c.
b.
d.
The following diagram illustrates an electrochemical cell circuit.
____ 17.
Which of the following statements are true of the circuit shown above?
I.
Electrons flow from the positive terminal to the negative terminal through the electrolyte.
II.
Electrons flow from the negative terminal to the positive terminal through the conducting wire.
III.
Bubbles of aluminum gas will form on one electrode.
IV.
Positive ions escape from the negative electrode.
V.
Positive ions escape from the positive electrode.
VI.
Positive ions escape from the electrolyte.
a. I and III
b. II, III, and V
c. II and IV
d. II and VI
____ 18. A change is made to the resistance of an element in an electrical circuit. As a result of the change, the current
through a load doubles, and the potential difference across the load is cut in half. What change was made to
the resistance?
a. The resistance was reduced by three quarters to one quarter of its original value.
b. The resistance reduced by one half.
c. The resistance was unchanged.
d. The resistance doubled.
____ 19. Three identical resistors are connected in series to a 6 V power supply. An ammeter is used to determine the
total current (I) through the 6 V power supply circuit. Which equation will give the resistance of the second
resistor?
a. Resistance = 6 V  I
b. Resistance = 6 V  I
c. Resistance = 6 V  3 I
d. Resistance = 6 V  3 I
____ 20. On a home’s electricity meter, what is measured in kilowatt-hours?
a. current
c. resistance
b. energy
d. cost
Matching
Match each term to one of the following definitions.
a. electrostatic spray painter
d. ionizer
b. lightning rod
e. electroscope
c. photocopier
____ 21. a machine that uses a metal that is a conductor in visible light and an insulator in the dark
____ 22. a conductor that protects buildings during storms
____ 23. a device that uses electric charge to remove pollutants from smokestacks
____ 24. a device that gives cars and trucks a smooth paint finish
____ 25. a device that is used to observe the presence of electric charge
Match the total resistance to one of the following arrangements of resistors.
a. one 30 resistor
b. one 50
resistor in series
c. two 10
resistors in parallel
d. three 5
resistors in series
e. three 3
resistors in parallel
f. two 30
resistors in series
____ 26. 1
____ 27. 5
____ 28. 15
____ 29. 30
____ 30. 60
Short Answer
31. List four conductors and four insulators.
32.
The illustration above shows a lemon being used in an electrochemical cell.
a) What does this tell you about the properties of lemon juice?
b) How would you investigate what other fruits or vegetables share this property?
33. What is the relationship between the resistance and the power rating of an electrical device connected to a
constant potential difference? (Hint: Use the equations P=IV and V=IR to answer the question. You may need
to rearrange the equations.)
Problem
34. The following diagram shows the charges that accumulate in two different balloons when they are rubbed.
What does this diagram tell you about the properties of the material from which each balloon is made?
Explain.
35. a) Explain what happens to a neutral electroscope when a positively charged rod is brought close to, but not
touching the electroscipe and then is pulled away.
b) Would your observations of the leaves of the electroscope change if a negatively charged rod were used
instead? Explain.
36. You are packing for a camping trip. Your younger brother helps put the batteries into your flashlight. All the
batteries are new and fully charged. When you reach your destination, however, you find that the flashlight
does not work. What might have gone wrong?
Unit 3 review
Answer Section
MODIFIED TRUE/FALSE
1. ANS:
OBJ:
KEY:
2. ANS:
OBJ:
KEY:
3. ANS:
OBJ:
KEY:
4. ANS:
OBJ:
KEY:
5. ANS:
OBJ:
KEY:
6. ANS:
T
Section 7.1
LOC: C5
grounding
T
Section 7.1
LOC: C5
coulomb
T
Section 7.1
LOC: C5
static charge
T
Section 7.1
LOC: C5
static charge
T
Section 7.2
LOC: C5
electroscope | induction
F, ampere
PTS: 1
DIF:
TOP: Static Charge
Easy
PTS: 1
DIF:
TOP: Static Charge
Easy
PTS: 1
DIF:
TOP: Static Charge
Average
PTS: 1
DIF:
TOP: Static Charge
Easy
PTS: 1
DIF:
TOP: Electric Force
Average
PTS:
TOP:
7. ANS:
OBJ:
KEY:
8. ANS:
1
DIF: Easy
Electric Current
T
Section 8.2
LOC: C6
source | circuit components
F, B
OBJ:
KEY:
PTS:
TOP:
Section 8.2
LOC: C6
ampere
1
DIF: Average
Electric Current
PTS:
TOP:
9. ANS:
OBJ:
KEY:
10. ANS:
1
DIF: Easy
Electric Current
T
Section 9.1
LOC: C7
parallel circuit
F, 9
OBJ:
KEY:
PTS:
TOP:
Section 8.2
LOC: C6
circuit components | conductor
1
DIF: Average
Series and Parallel Circuits
PTS: 1
DIF: Average
TOP: Series and Parallel Circuits
OBJ: Section 9.1
LOC: C7
KEY: series circuit | resistance
MULTIPLE CHOICE
11. ANS:
LOC:
12. ANS:
LOC:
13. ANS:
LOC:
A
C5
C
C5
B
C6
PTS:
TOP:
PTS:
TOP:
PTS:
TOP:
1
DIF: Difficult
Static Charge
1
DIF: Easy
Static Charge
1
DIF: Average
Electric Current
OBJ:
KEY:
OBJ:
KEY:
OBJ:
KEY:
Section 7.1
properties of electric charges
Section 7.1
electron transfer
Section 8.2
current
14. ANS:
LOC:
15. ANS:
LOC:
16. ANS:
LOC:
17. ANS:
LOC:
KEY:
18. ANS:
LOC:
19. ANS:
LOC:
20. ANS:
LOC:
B
PTS:
C6
TOP:
C
PTS:
C6
TOP:
D
PTS:
C6
TOP:
C
PTS:
C6
TOP:
electrochemical cell
A
PTS:
C6
TOP:
C
PTS:
C7
TOP:
B
PTS:
C8
TOP:
1
DIF: Average
OBJ:
Resistance and Ohm's Law
KEY:
1
DIF: Average
OBJ:
Resistance and Ohm's Law
KEY:
1
DIF: Difficult
OBJ:
Resistance and Ohm's Law
KEY:
1
DIF: Difficult
OBJ:
Electric Potential Energy and Voltage
Section 8.3
current
Section 8.3
Ohm's law
Section 8.3
Ohm's law
Section 8.1
1
DIF: Difficult
Resistance and Ohm's Law
1
DIF: Difficult
Series and Parallel Circuits
1
DIF: Average
The Power of Electricity
OBJ:
KEY:
OBJ:
KEY:
OBJ:
KEY:
Section 8.3
Ohm's law
Section 9.1
series circuit
Section 9.2
household energy use
21. ANS:
LOC:
22. ANS:
LOC:
23. ANS:
LOC:
24. ANS:
LOC:
25. ANS:
LOC:
C
C5
B
C5
D
C5
A
C5
E
C5
PTS:
TOP:
PTS:
TOP:
PTS:
TOP:
PTS:
TOP:
PTS:
TOP:
1
Electric Force
1
Static Charge
1
Static Charge
1
Static Charge
1
Electric Force
OBJ:
KEY:
OBJ:
KEY:
OBJ:
KEY:
OBJ:
KEY:
OBJ:
KEY:
Section 7.2
photocopier
Section 7.1
grounding
Section 7.1
applications of static charge
Section 7.1
applications of static charge
Section 7.2
electroscope
26. ANS:
LOC:
27. ANS:
LOC:
28. ANS:
LOC:
29. ANS:
LOC:
30. ANS:
LOC:
E
C7
C
C7
D
C7
A
C7
F
C7
PTS:
TOP:
PTS:
TOP:
PTS:
TOP:
PTS:
TOP:
PTS:
TOP:
1
DIF: Difficult
Series and Parallel Circuits
1
DIF: Difficult
Series and Parallel Circuits
1
DIF: Difficult
Series and Parallel Circuits
1
DIF: Difficult
Series and Parallel Circuits
1
DIF: Difficult
Series and Parallel Circuits
OBJ:
KEY:
OBJ:
KEY:
OBJ:
KEY:
OBJ:
KEY:
OBJ:
KEY:
Section 9.1
parallel circuit
Section 9.1
parallel circuit
Section 9.1
series circuit
Section 9.1
series circuit
Section 9.1
series circuit
MATCHING
DIF: Average
DIF: Average
DIF: Average
DIF: Average
DIF: Average
SHORT ANSWER
31. ANS:
Any four of the following:
Conductors: Copper, aluminum, salt water, gold, iron, nickel, magnesium, mercury, platinum, silver,
tungsten, silicon, carbon, Earth, the human body, humid air, nichrome
Insulators: Amber, plastic, rubber, pure water, silk, glass, ebonite, cotton, fur, paper, porcelain, sulfur, wood,
wool
PTS: 4
DIF: Easy
OBJ: Section 7.1
LOC: C5
TOP: Static Charge
KEY: conductors | insulator
32. ANS:
a)
This tells you that lemon juice is an electrolyte (it can conduct electricity).
b)
Replace the lemon in the circuit with other fruits or vegetables and observe the ammeter. Any current
indicates that the fruit or vegetable can conduct electricity.
PTS: 1
DIF: Easy
OBJ: Section 8.1
LOC: C6
TOP: Electric Potential Energy and Voltage
KEY: electrochemical cell
33. ANS:
Power is the product of current and voltage. Given a constant voltage, power increases only with an increase
in the current. Current is voltage divided by resistance. Given a constant voltage, current increases only with a
reduction in resistance. Therefore, the power of a device increases with a decrease in its resistance. That is, a
high-power device is one with a low resistance.
PTS: 3
DIF: Difficult
TOP: The Power of Electricity
OBJ: Section 9.2
LOC: C8
KEY: resistance | power
PROBLEM
34. ANS:
1) In balloon A the charge remains in one place. This indicates that balloon A is made of an insulating
material such as rubber.
2) In balloon B the charges move freely over the surface of the balloon. This indicates that balloon B is made
of a conducting material such as a metallic substance.
PTS: 1
DIF: Average
OBJ: Section 7.2
LOC: C5
TOP: Electric Force
KEY: laws of static charge | properties of electric charges
35. ANS:
a) Electrons will move up from the leaves to the bulb of the electroscope since they are attracted to the
positively charged rod. The leaves will move apart from each other because they both carry a positive charge,
so they repel each other. When the rod is pulled away, the leaves will move back to their original position as
the electrons move back to an even distribution within the electroscope.
b) No. Electrons would move from the bulb to the leaves since they would be repelled by the negative charge
of the rod, but the leaves would still move apart because they would both carry negative charges, which
would repel each other.
PTS: 2
DIF: Difficult
OBJ: Section 7.2
LOC: C5
TOP: Electric Force
KEY: electroscope | induction
36. ANS:
One or more of the batteries may have been inserted so that the positive and negative terminals were reversed.
This breaks the circuit and prevents current from flowing through the flashlight bulb.
PTS: 1
DIF: Average
OBJ: Section 8.1
TOP: Electric Potential Energy and Voltage
LOC: C6
KEY: electrochemical cell