Name______________________________ Per _______________
Chapter 17, Section 1 Practice A, page 599

These practice problems require the use of the formulas:
PEelectric  qEd
V 
PEelectric
q
V  Ed
V  k C
q
r
1. As a particle moves 10.0 m along an electric field of strength
75
-16
N/C, its electrical potential energy decreases by 4.8 x10 J. What is
the particle’s charge?
1st determine what you need to find
2nd determine what variable each number is.
3rd determine which equation to use.
4th solve the equation

2. What is the potential difference between the initial and final locations of the
particle in Problem 1?
3. An electron (qe = -1.6 x 10-19 C) moves 4.5 m in the direction of an electric field of strength 325 N/C.
Determine the change in electrical potential energy.
“Ignorance is a virus. Once it starts spreading, it can only be cured by reason. For the sake of humanity, we must be that
cure.” Neil deGrasse Tyson
Page 1
Chapter 17, Section 1 Review, page 601
1. What is the difference between PEelectric and PEelectric?

1st determine what you need to find
2nd determine what variable each number is.
3rd determine which equation to use.
4th solve the equation
2. In a uniform electric field, what factors does the electrical
potential energy depend on?

3. Describe the conditions that are necessary for mechanical energy to be a conserved quantity.
4. Is there a single correct reference point from which all electrical potential energy measurements must be
taken?
5. A uniform electric field with a magnitude of 250 N/C is directed in the positive x direction. A 12 x 10-6 C
charge moves from the origin to the point (.2 m, .5 m). What is the change in the electrical potential energy
of the system as a result of the change in position of this charge?
6. What is the change in the electrical potential energy in a lightning bolt if 35 C of charge travel to the ground
from a cloud 2000 m above the ground in the direction of the field? Assume the electric field is uniform and
has a magnitude of 1.0 x 106 N/C.
More problems on next page.
“Ignorance is a virus. Once it starts spreading, it can only be cured by reason. For the sake of humanity, we must be that
cure.” Neil deGrasse Tyson
Page 2
7. The gap between electrodes in a spark plug is 6.0 x 10-4 m. Producing an electric spark in a gasoline-air
mixture requires an electric field of 3.0 x 106 V/m. what minimum potential difference must be supplied by
the ignition circuit to start a car?
8. A proton (qp = +1.6 x 10-19 C) is released from rest in a uniform electric field with a magnitude of
8.0 x 104 V/m. the proton is displaced 0.50 m as a result.
a. Find the potential difference between the proton’s initial and final positions.
b. Find the change in electrical potential energy of the proton as a result of this displacement.
9. In a thunderstorm, the air must be ionized by a high voltage before a conducting path for a lightning bolt can
be created. An electric field of about 1.0 x 106 V/v is required to ionize dry air. What would the breakdown
voltage in air be if a thundercloud were 1600 m above ground? Assume that the electric field between the
cloud and the ground is uniform.
10. Explain how electric potential and potential difference are related. What units are used for each one?
11. Given the electrical potential energy, how do you calculate electric potential?
12. Why is the electric potential a more useful quantity for most calculations than electrical potential energy is?
“Ignorance is a virus. Once it starts spreading, it can only be cured by reason. For the sake of humanity, we must be that
cure.” Neil deGrasse Tyson
Page 3
Chapter 17, Section 2 Practice B, page 607
Q
C
V
PEelec
1
2
 C V 
2
A
C  0
d

1st determine what you need to find
2nd determine what variable each number is.
-6
1. A 4.00 x 10 F capacitor is connected to a 12.0 V battery.
a. What is the charge on each plate of the capacitor?
3rd determine which equation to use.
4th solve the equation

b. If this same capacitor is connected to a 1.50 V battery, how much electrical potential energy is stored?
2. A parallel-plate capacitor has a charge of 6.00 x 10-6 C when it is charged by a potential difference of 1.25 V.
a. Find its capacitance.
b. How much electrical potential energy is stored when this capacitor is connected to a 1.50 V battery?
3. A capacitor has a capacitance of 2.00 x 10-12 F.
a. What potential difference would be required to store 18.0 x 10-12 C?
b. How much charge is stored when the potential difference is 2.5 V?
4. You are asked to design a parallel-plate capacitor having a capacitance of 1.00 F and a plate separation of
.001 m. Calculate the required surface area of each plate (ε0 = 8.85 x 10-12 C2/Nm2)
“Ignorance is a virus. Once it starts spreading, it can only be cured by reason. For the sake of humanity, we must be that
cure.” Neil deGrasse Tyson
Page 4

Chapter 17, Section 2 Review, page 607
1st determine what you need to find
1. Assume Earth and a cloud layer 800.0 m above the Earth can be
treated as plates of a parallel-plate capacitor.
a. If the cloud layer has an area of 1.00 x 106 m2, what is the
2nd determine what variable each number is.
capacitance? Eo = 8.85 x 10 -12
4th solve the equation
3rd determine which equation to use.

b. If an electric field strength of 2.0 x 106 N/C causes the air to conduct charge (lightning), what charge can the
cloud hold?
2. A parallel-plate capacitor has an area of .02 m2, and the plates are separated by .002 m.
a. What is the capacitance?
b. How much charge does the capacitor store when connected to a 6.0 V battery?
3. A parallel-plate capacitor has a capacitance of 1.35 x 10-12 F. If a 12.0 V battery is connected to this capacitor,
how much electrical potential energy would it store?
4. Explain why two metal plates near each other will not become charged unless they are connected to a source
of potential difference.
“Ignorance is a virus. Once it starts spreading, it can only be cured by reason. For the sake of humanity, we must be that
cure.” Neil deGrasse Tyson
Page 5
Chapter 17, Section 3 Practice C, page 609
These practice problems require the use of the formulas:
I
Q
t
1. If the current in a wire of a CD player is 5 x 10-3 A, how long would it
take for 2 C of charge to pass through a cross-sectional area of this
wire?

1st determine what you need to find
2nd determine what variable each number is.
3rd determine which equation to use.
4th solve the equation

2. In a particular television tube, the beam current is 6 x 10-5 A. How long does it take for 3.75 x 1014 electrons
to strike the screen? ( Remember that one electron has a charge of -1.6 x 10-19 C)
3. If a metal wire carries a current of 8 x 10-2 A, how long does it take for 3 x 1020 electrons to pass a given
cross-sectional area of the wire?
Remember: # e- = Q
So Q = # e- (1.6x 10-19C) =
Q/e-
4. The compressor on an air conditioner draws 40 A when it starts up. If the start-up time is .5 s, how much
charge passes a cross-sectional area of the circuit in this time?
5. A total charge of 9 x 10-3 C passes through a cross-sectional area of a nichrome wire in 3.5 s.
a. What is the current in the wire?
b. How many electrons pass through the cross-sectional area in
10 s?
c. If the number of charges that pass through the cross-sectional area during the given time interval
doubles, what is the resulting current?
“Ignorance is a virus. Once it starts spreading, it can only be cured by reason. For the sake of humanity, we must be that
cure.” Neil deGrasse Tyson
Page 6

Chapter 17, Section 3 Practice D, page 615
These practice problems require the use of the formulas:
V  IR
1st determine what you need to find
2nd determine what variable each number is.
3rd determine which equation to use.
1. A 1.5 V battery is connected to a small light bulb with a resistance
of 3.5 . What is the current in the bulb?
4th solve the equation

2. A stereo with a resistance of 65  is connected across a potential difference of 120 V. What is the current in
this device?
3. Find the current in the following devices when they are connected across a potential difference of 120 V.
a. A hot plate with a resistance of 48 .
b. A microwave oven with a resistance of 20 .
4. The current in a microwave oven is 6.25 A. If the resistance of the oven’s
circuitry is 17.6 , what is the potential difference across the oven?
5. A typical color television draws 2.5 A of current when connected across a potential difference of 115 V.
What is the effective resistance of the television set?
6. The current in certain resistor is 0.50 A when it is connected to a potential difference of 110 V. What is the
current in this same resistor if
a. The operating potential difference is 90 V?
b. The operating potential difference is 130 V?
“Ignorance is a virus. Once it starts spreading, it can only be cured by reason. For the sake of humanity, we must be that
cure.” Neil deGrasse Tyson
Page 7
Chapter 17, Section 3 Review, page 616
1.
Can the direction of conventional current ever be opposite
the direction of charge movement? If so, when?

1st determine what you need to find
2nd determine what variable each number is.
3rd determine which equation to use.
2.
The charge that passes through the filament of a certain light
bulb in 5 s is 3 C.
a. What is the current in the light bulb?
4th solve the equation

b. How many electrons pass through the filament of the
light bulb in a time interval of 1 min?
3.
How much current would a 10.2  toaster oven draw when
connected a 120 V outlet?
4.
An ammeter registers 2.5 A of current in a wire that is connected to a 9 V battery. What is the wire’s
resistance?
5.
In a particular diode, the current triples when the applied potential difference is doubled. What can you
conclude about the diode?
6.
What is the function of resistors in a circuit board? What is the function of diodes in a circuit board?
7.
Calculate the current in a 75  resistor when a potential difference of 115 V is placed across it. What will
the current be if the resistor is replaced with a 47  resistor?
8.
In a conductor that carries a current, which is less, the drift speed of an electron or the average speed of
the electron between collisions? Explain your answer.
9.
You have only one type of wire. If you are connecting a battery to a light bulb with this wire, how could
you decrease the current in the wire?
“Ignorance is a virus. Once it starts spreading, it can only be cured by reason. For the sake of humanity, we must be that
cure.” Neil deGrasse Tyson
Page 8
Chapter 17, Section 4 Practice E, page 621

These practice problems require the use of the formulas:
2

V 
P
R
P  IV
V  IR
1.
A 1050 W electric toaster operates on a household circuit of
120 V. What is the resistance of the wire that makes up the heating
element of the toaster?
2.
1st determine what you need to find
2nd determine what variable each number is.
3rd determine which equation to use.
4th solve the equation

A small electronic device is rated at .25 W when connected 120 V. What is the resistance of this device?
3.
A calculator is rated at .1 W and has an internal
resistance of 22 . What battery potential difference is
required for this device?
4.
An electric heater is operated by applying a potential difference of 50 V across a wire of total resistance
8 . Find the current in the wire and the power rating of the heater.
5.
What would the current in the heater in Problem 4 be if the wire developed a short and the resistance
was reduced to .1 .
“Ignorance is a virus. Once it starts spreading, it can only be cured by reason. For the sake of humanity, we must be that
cure.” Neil deGrasse Tyson
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Chapter 17, Section 4 Review, page 623
1.
What does the power rating on a light bulb describe?

1st determine what you need to find
2nd determine what variable each number is.
3rd determine which equation to use.
4th solve the equation

2.
If the resistance of a light bulb is increased, how will the
electrical energy used by the light bulb over the same time period change?
3.
The potential difference across a resting neuron in the
human body is about 70 x 10-3 V, and the current in it is
approximately 200 x 10-3 A. How much power does the neuron
release?
4.
How much does it cost to watch an entire World Series (21 hours) on a 90 W television set? Assume that
electrical energy costs $.070/1000 Whour.
5.
Explain why it is more efficient to transport electrical energy at high potential differences and low
currents rather than at low potential differences and high currents.
“Ignorance is a virus. Once it starts spreading, it can only be cured by reason. For the sake of humanity, we must be that
cure.” Neil deGrasse Tyson
Page 10
Chapter 17, Chapter Review, page 626
3.
Differentiate between electrical potential energy and electric
potential.

1st determine what you need to find
2nd determine what variable each number is.
3rd determine which equation to use.
4th solve the equation

6.
If the electric field in some region is zero, must the electric potential in that same region also be zero?
Explain your answer.
12.
Why is the Earth considered a “ground” in electric terms? Can any other object act as a ground?
17.
Why is it dangerous to touch the terminals of a high-voltage capacitor even after the potential
difference has been removed? What can be done to make the capacitor safe to handle?
21.
In a metal conductor, current is the result of moving electrons. Can charge carriers ever be positive?
24.
There is a current in a metal wire due to the motion of electrons. Sketch a possible path for the motion
of a single electron in this wire, the direction of the electric field vector, and the direction of conventional
current.
More problems on next page
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cure.” Neil deGrasse Tyson
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27.
In an analogy between traffic flow and electric current, what would correspond to the charge, Q? What
would correspond to the current, I?
30.
When a light bulb is connected to a battery, charges begin moving almost immediately, although each
electron travels very slowly across the wire. Explain why the bulb lights up so quickly.
32.
How long does it take a total charge of 10 C to pass through a cross-sectional area of a copper wire that
carries a current of 5 A?
35.
Each of the wires shown to the right is made of copper.
Assuming each piece of wire is at the same temperature, which
has the greatest resistance? Which has the least resistance?
38.
If the potential difference across a conductor is constant, how is current dependent on resistance?
40.
A Nichrome wire with a resistance of 15  is connected across the terminals of a 3 V flashlight battery.
How much current is in the wire?
43.
Why must energy be continuously pumped into a circuit by a battery or a generator to maintain an
electric current?
“Ignorance is a virus. Once it starts spreading, it can only be cured by reason. For the sake of humanity, we must be that
cure.” Neil deGrasse Tyson
Page 12