Download Static Electricity NAME_________________________ Guided

Static Electricity
NAME_________________________
Guided Reading and Homework problems– The Physics Classroom –
http://www.glenbrook.k12.il.us/gbssci/Phys/Class/estatics/estaticstoc.html
Lesson 1: Basic Terminology and Concepts
The Structure of Matter
1.
Name four example of static electricity.
2.
Why is life as we know it impossible without static electricity?
3.
Why do we need to know chemistry to understand electrostatics?
4.
What did and didn’t Greeks offer to our understanding of atoms?
5. List six of the scientists that added to our understanding of the atom and what they accomplished.
a.
b.
c.
d.
e.
f.
6.
a.
Summarize three point of the Atomic Theory:
b.
c.
7.
______________________________ are the charged parts of an atom.
Neutral vs. Charged Objects
8.
TRUE of FALSE: An object which is positively charged contains all protons and no electrons.
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9.
TRUE of FALSE: An object which is negatively charged could contain only electrons with no accompanying
protons.
10. TRUE of FALSE: An object which is electrically neutral contains only neutrons.
11. Identify the following particles as being charged or uncharged. If charged, indicate whether they are charged
positively or negatively. (n = neutron, p = proton, e = electron)
12. Consider the graphic at the right of a neutral oxygen atom
a. Explain what must happen in order for the oxygen atom to become negatively
charged.
b.
Explain what must happen in order for the oxygen atom to become positively
charged.
c.
13. A coulomb is a measure of __________________________. It contains __________________________________
of electrons.
14. Determine the quantity and type of charge on an object which has 4.57 x 1012 more protons than electrons.
15. Complete the following statements: After some rather exhausting counting (and a rather tall tale), a physics
teacher determines that a very small sample of an object contains ...
a. ….8.25749 x 1017 protons and 5.26 x 1014 electrons; the charge on this object is ____ Coulombs.
b. ... 3.12 x 1014 protons and 4.5488 x 1016 electrons; the charge on this object is ____ Coulombs.
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c. ... 4.5678 x 1019 protons and 9.88 x 1016 electrons; the charge on this object is ____ Coulombs.
d. ... 4.5678 x 1015 protons and 2.6325 x 1015 electrons; the charge on this object is ____ Coulombs.
16. The amount of charge carried by a lightning bolt is estimated at 10 Coulombs. What quantity of excess electrons is
carried by the lightning bolt?
17. "A positively charged object is an object which has an excess of positive electrons.” How would you respond to
this?
Charge Interactions
18. How do Electrical forces cause attraction or repulsions?
19. On two occasions, the following charge interactions between balloons A, B and C are observed. In each case, it is
known that balloon B is charged negatively. Based on these observations, what can you conclusively confirm about
the charge on balloon A and C for each situation.
20. Upon entering the room, you observe two balloons suspended from the ceiling. You notice
that instead of hanging straight down vertically, the balloons seems to be repelling each
other.
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a.
You can conclusively say ...
b.
Explain your answer.
21. Jean Yuss is investigating the charge on several objects and makes the following findings.
Object C
attracts B
Object D
repels C
Object E
attracts D
Object F
attracts A
repels F
Jean knows that object A is negatively charged and object B is electrically neutral. What can Jean Yuss definitively
conclude about the charge on objects C, D, E, and F? Explain.
22. Two objects are charged as shown at the right. Object X will ____ objectY.
23. Two objects are shown at the right. One is neutral and the other is negative. Object X will
____ object Y.
24. Balloons X , Y and Z are suspended from strings as shown at the right.
Negatively charged balloon X attracts balloon Y and balloon Y attracts
balloon Z. Balloon Z ____. List all that apply.
A. may be positively charged
B. may be negatively charged.
C. may be neutral.
D. must be positively charged
E. must be negatively charged. F. must be neutral
(NOTE: This is an exercise in logic and reasoning as much as it is an exercise in physics.)
Conductors and Insulators
25. What are the difference between conductors and insulators with regards to how they
surfaces?
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distribute charge on their
26. How does a Vander Graff generator demonstrate affects of excess charge?
27. One of these isolated charged spheres is copper and the other is rubber. The diagram below depicts the distribution
of excess negative charge over the surface of two spheres. Label which is which and support your answer with an
explanation.
28. Which of the following materials are likely to exhibit more conductive properties than insulating properties? _____
Explain your answers.
a. rubber
b. aluminum
c. silver
d. plastic
e. wet skin
29. Suppose that a conducting sphere is charged positively by some method. The charge is initially deposited on the left
side of the sphere. Yet because the object is conductive, the charge spreads uniformly throughout the surface of the
sphere. The uniform distribution of charge is explained by the fact that ____.
a. the charged atoms at the location of charge move throughout the surface of the sphere
b. the excess protons move from the location of charge to the rest of the sphere
c. excess electrons from the rest of the sphere are attracted towards the excess protons
30. When an oil tanker car has arrived at its destination, it prepares to empty its fuel into a reservoir or tank. Part of the
preparation involves connecting the body of the tanker car with a metal wire to the ground. Suggest a reason for
why is this done
Polarization
31. A rubber balloon possess a positive charge. If brought near and touched to the door of a wooden cabinet, it sticks to
the door. This does not occur with an uncharged balloon. These two observations can lead one to conclude that the
wall is _____.
a. electrically neutral
c. a conductor
b. negatively charged
d. lacking electrons
32. Which of the diagrams below best represents the charge distribution on a metal sphere when a positively charged
plastic tube is placed nearby?
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33. The distribution of electric charge in a H2O molecule is nonuniform. The more electronegative oxygen atom attracts
electrons from the hydrogen atom. Thus, the oxygen atoms acquire a partial negative charge and the hydrogen
atoms acquire a partial positive charge. The water molecule is "polarized." Which diagram(s) below correctly
portray(s) a pair of H2O molecules? Explain.
34. True or False: When an object becomes polarized, it acquires a charge and becomes a charged object.
35. Charged rubber rods are placed near a neutral conducting sphere, causing a redistribution of charge on the spheres.
Which of the diagrams below depict the proper distribution of charge on the spheres? List all that apply.
36. In the above situation, the conducting sphere is ____. List all that apply.
a. charged
b. uncharged (neutral)
c. polarized
Lesson 2: Methods of Charging
Charging by Friction
37. During a physics lab, a plastic strip was rubbed with cotton and became positively charged. The correct explanation
for why the plastic strip becomes positively charged is that ...
a. the plastic strip acquired extra protons from the cotton. b. the plastic strip acquired extra protons during the
charging process. c. protons were created as the result of the charging process. d. the plastic strip lost electrons to
the cotton during the charging process.
38. Saran Wrap has a larger electron affinity than Nylon. If Nylon is rubbed against Saran Wrap, which would end up
with the excess negative charge? ____________ Explain.
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39. A physics teacher rubs a glass object and a felt cloth together and the glass becomes positively charged. Which of
the following statements are true? Circle all that apply.
a. The glass gained protons during the rubbing process. b. The felt became charged negatively during this rubbing
process. c. Charge is created during the rubbing process; it is grabbed by the more charge-hungry object. d. If the
glass acquired a charge of +5 units, then the felt acquires a charge of -5 units. e. This event violates the law of
conservation of charge. f. Electrons are transferred from glass to felt; protons are transferred from felt to glass.
g. Once charged in this manner, the glass object and the felt cloth should attract each other h. In general, glass
materials must have a greater affinity for electrons than felt materials.
40. Which statement best explains why a rubber rod becomes negatively charged when rubbed with fur?
a. The rubber which the rod is made of is a better insulator than fur. b. The fur is a better insulator than the rubber
c. Molecules in the rubber rod have a stronger attraction for electrons than the molecules in the fur. d. Molecules in
the fur have a stronger attraction for electrons than the molecules in the rubber rod
Charging by Induction
41. Two neutral conducting pop cans are touching each other. A positively charged balloon is brought near one of the
cans as shown below. The cans are separated while the balloon is nearby, as shown. After the balloon is removed
the cans are brought back together. When touching again, can X is ____.
a. positively charged
c. neutral
b. negatively charged
d. impossible to tell
42. Two neutral conducting pop cans are touching each other. A positively charged glass rod is brought near Can X as
shown below. Which of the following occur as the glass rod approaches Can X?
List all that apply.
a. Electrons jump from the glass rod to can X. b. Electrons jump from the glass
rod to can Y. c. Electrons jump from can X to the glass rod. d. Electrons jump
from can Y to the glass rod. e. Protons jump from the glass rod to can X. f.
Protons jump from can X to the glass rod.g. ... nonsense! None of these occur.
43. TRUE or FALSE?Two neutral conducting pop cans are touching each other. A
negatively charged balloon is brought near Can X as shown below. As the
balloon approaches Can X, there is a movement of electrons between the
balloon and can X (in one direction or the other).
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44. A positively charged balloon is brought near a neutral conducting sphere as shown below. While the balloon is
near, the sphere is touched (grounded).
45. At this point, there is a movement of electrons. Electrons move ____ .
a. into the sphere from the ground (hand) b. out of the sphere into the ground (hand) c. into the sphere from the
balloond. out of the sphere into the balloone. from the ground through the sphere to the balloon f. from the balloon
through the sphere to the ground g. .... nonsense! Electrons do not move at all.
46. Suppose that a negatively charged balloon is used to charge an electroscope by induction. The procedural steps are
described in the educational cartoon below. On the cartoon, draw the orientation of the needle and indicate the
location and type of any excess charge in steps ii. - v. Explain in terms of electron movement what is happening in
each step.
47. A negatively charged balloon is brought near a neutral conducting sphere as shown below. As it approaches, charge
within the sphere will distribute itself in a very specific manner. Which one of the diagrams below properly depicts
the distribution of charge in the sphere?
48. A positively charged piece of Styrofoam is placed on the table. A neutral aluminum pie plate is brought near as
shown below. While held above the Styrofoam, the aluminum plate is touched (grounded).
At this point, there is a movement of electrons. Electrons move ____ .
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a. out of the aluminum plate into the ground (hand) b. into the aluminum plate from the ground (hand) c. into the
aluminum plate from the Styrofoam d. out of the aluminum plate into the Styrofoam e. from the ground through
the aluminum plate to the Styrofoam f. from the Styrofoam through the aluminum plate to the ground g. ....
nonsense! Electrons do not move at all.
Charging by Conduction
49. A neutral metal sphere is touched by a negatively charged metal rod. As a result, the sphere will be ____ and the
metal rod will be ____. Select the two answers in their respective order.
a. positively charged b. negatively charged c. neutral d. much more massive e. ... not enough information to tell
50. A neutral metal sphere is touched by a negatively charged metal rod. During the process, electrons are transferred
from the _____ to the _____ and the sphere acquires a _____ charge.
a. neutral sphere, charged rod, negative b. neutral sphere, charged rod, positive c. charged rod, neutral sphere, negative
d. charged rod, neutral sphere, positive e. ... nonsense! None of these describe what occurs.
51. A neutral metal sphere is touched by a positively charged metal rod. During the process, protons are transferred
from the _____ to the _____ and the sphere acquires a _____ charge.
a. charged rod, neutral sphere, negative b. charged rod, neutral sphere, positive c. neutral sphere, charged rod,
negative d. neutral sphere, charged rod, positive e. ... nonsense! None of these describe what occurs.
52. . A metal sphere is electrically neutral. It is touched by a positively charged metal rod. As a result, the metal sphere becomes
charged positively. Which of the following occur during the process? List all that apply.
a. The metal sphere gains some protons. b. Electrons are transferred from the sphere to the rod. c. The metal sphere loses
electrons. d. The overall charge of the system is conserved. e. Protons are transferred from the rod to the sphere. f. Positive
electrons are moved between the two objects.
Grounding - the Removal of a Charge
53.. A positively charged pop can is touched by a person standing on the ground. The pop can subsequently becomes neutral. The
pop can becomes neutral during this process because ______.
a. electrons pass from the pop can to the person (ground) b. electrons pass from the person (ground) to the pop can c. protons
pass from the pop can to the person (ground) d. protons pass from the person (ground) to the pop can
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54. A physics student, standing on the ground, touches an uncharged plastic baseball bat to a negatively charged electroscope.
This will cause ___.
a. the electroscope to be grounded as electrons flow out of the electroscope. b. the electroscope to be grounded as electrons flow
into the electroscope. c. the electroscope to be grounded as protons flow out of the electroscope. d. the electroscope to be
grounded as protons flow into the electroscope. e. the baseball bat to acquire an excess of protons. f. absolutely nothing (or very
little) to happen since the plastic bat does not conduct.
55. TRUE or FALSE: An object that becomes grounded gains neutrons during the grounding process.
Lesson 3: Electric Force
Charge Interactions Revisited
56. Name one way that Electric Force relates to Newtons’ Laws
Coulomb's Law
57. What are the three variables you have to consider when calculating electrical force?
58. What is the formula for Coulomb’s law and what do each of the variables mean?
59. Do objects get a charge of one coubomb?
60. What are more common measures of charge?
61. Name one way that Coulomb’s law is similar to Universal Law of Gravity. Name one way they are dissimilar.
62.. The Q in Coulomb's law equation stands for the _____.
a. mass of a charged object
c. the current of a charged object
e. charge of a charged object
b. # of excess electrons on the object
d. the distance between charged objects
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63.. The symbol d in Coulomb's law equation represents the distance from ___.
a. A to B
e. C to D
b. A to D
f. A to G
c. B to C
g. B to F
d. B to D
h. C to E
64. Determine the electrical force of attraction between two balloons with separate charges of +3.5 x 10 -8 C and -2.9 x 10-8 C
when separated a distance of 0.65 m.
65. Determine the electrical force of attraction between two balloons which are charged with the opposite type of charge but the
same quantity of charge. The charge on the balloons is 6.0 x 10 -7 C and they are separated by a distance of 0.50 m.
66. Joann has rubbed a balloon with wool to give it a charge of -1.0 x 10-6 C. She then acquires a plastic golf tube with a charge
of +4.0 x 10-6 C localized at a given position. She holds the location of charge on the plastic golf tube a distance of 50.0 cm
above the balloon. Determine the electrical force of attraction between the golf tube and the balloon.
67.. A balloon with a charge of 4.0 µC is held a distance of 0.70 m from a second balloon having the same charge. Calculate the
magnitude of the repulsive force.
68. At what distance of separation must two 1.00-microCoulomb charges be positioned in order for the repulsive force between
them to be equivalent to the weight (on Earth) of a 1.00-kg mass?
Inverse Square Law
69. What does it mean “Equations can be more than merely recipes for algebraic problem-solving; they can be
"guides to thinking."?
Alteration in the Quantity of Charge
70.. Two charged objects have a repulsive force of 0.080 N. If the charge of one of the objects is doubled, then what is the new
force?
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71. Two charged objects have a repulsive force of 0.080 N. If the charge of both of the objects is doubled, then what is the new
force?
Alteration in the Distance between Charged Objects
72. Two charged objects have a repulsive force of 0.080 N. If the distance separating the objects is doubled, then what is the new
force?
73. Two charged objects have a repulsive force of 0.080 N. If the distance separating the objects is tripled, then what is the new
force?
74. Two charged objects have an attractive force of 0.080 N. If the distance separating the objects is quadrupled, then what is the
new force?
75. Two charged objects have a repulsive force of 0.080 N. If the distance separating the objects is halved, then what is the new
force?
Alteration in both the Quantity of Charge and the Distance
76. Two charged objects have a repulsive force of 0.080 N. If the charge of one of the objects is doubled, and the distance
separating the objects is doubled, then what is the new force?
77. Two charged objects have a repulsive force of 0.080 N. If the charge of both of the objects is doubled and the distance
separating the objects is doubled, then what is the new force?
78. Two charged objects have an attractive force of 0.080 N. If the charge of one of the objects is increased by a factor of four,
and the distance separating the objects is doubled, then what is the new force?
79. Two charged objects have an attractive force of 0.080 N. If the charge of one of the objects is tripled and the distance
separating the objects is tripled, then what is the new force?
Newton's Laws and the Electrical Force
80. Draw the force diagram for the leviataion of the balloon problem.
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81. Draw the force diagram for the ballons hanging from the strings.
83. Draw the force diagram for the four charges – but draw it for letter B.
84. A positively charged object with a charge of +85 nC is being used to balance the downward force of gravity on a 1.8-gram
balloon which has a charge of -63 nC. How high above the balloon must the object be held in order to balance the balloon?
(NOTE: 1 nC = 1 x 109 C)
85. Balloon A and Balloon B are charged in a like manner by rubbing with animal fur. Each acquires an excess of 25 trillion
electrons. If the mass of the balloons is 1 gram, then how far below Balloon B must Balloon A be held in order to levitate
Balloon B? Assume the balloons act as point charges.
86. Two 1.2-gram balloons are suspended from light strings attached to the ceiling at the same point. The net charge on the
balloons is -540 nC. The balloons are distanced 68.2 cm apart when at equilibrium. Determine the length of the string.
87. ZINGER: Three charges are placed along the X-axis. Charge A is a +18 nC charge placed at the origin. Charge B is a -27 nC
charge placed at the 60 cm location. Where along the axis (at what x-coordinate?) must positively charged C be placed in order to
be at equilibrium?
Lesson 4: Electric Fields
Action-at-a-Distance
88. Name two examples of forces acting over a distance (non-contact).
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89. Does the auther think WWF is contact or noncontact force?
90.What does scientists use to explain non-contact forces?
91. What does a stinky diaper have to do with a force field?
Electric Field Intensity
92. What is the equation and what are the variables for an Electric Field?
93. In your opinion, is insight better than ignorance? WHY?
94. Why doesn’t E (electric field strenght) depend on the size of q (charge at the point), if though it is in the equation?
95. What is the other Electric field equation and are the variable?
96. In the stinking field revisit, does a stinking person interupt a stinky diaper?
97. Charge Q acts as a point charge to create an electric field. Its strength, measured a distance of 30 cm away, is 40 N/C. What is
the magnitude of the electric field strength that you would expect to be measured at a distance of ...
a. 60 cm away? b. 15 cm away?c. 90 cm away?d. 3 cm away?c. 45 cm away?
98. Charge Q acts as a point charge to create an electric field. Its strength, measured a distance of 30 cm away, is 40 N/C. What
would be the electric field strength ...
a. 30 cm away from a source with charge 2Q? b. 30 cm away from a source with charge 3Q? c. 60 cm away from a source with
charge 2Q? d. 15 cm away from a source with charge 2Q? e. 150 cm away from a source with charge 0.5Q?
99. Use your understanding of electric field strength to complete the following table.
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100. In the table above, identify at least two rows which illustrate that the strength of the electric field vector is ...
a. directly related to the quantity of charge on the source charge (Q). b. inversely related to the square of the separation distance
(d).c. independent of the quantity of charge on the test charge (q).
101. The following unit is certainly not the standard unit for expressing the quantity electric field strength.
kg • m / s2 / C
However, it could be an acceptable unit for E. Use unit analysis to identify whether the above set of units is an acceptable unit for
electric field strength.
102. It is observed that Balloon A is charged negatively. Balloon B exerts a repulsive affect upon balloon A. Would the electric
field vector created by balloon B be directed towards B or away from B? ___________ Explain your reasoning.
103. A negative source charge (Q) is shown in the diagram below. This source charge can create an electric field. Various
locations within the field are labeled. For each location, draw an electric field vector in the appropriate direction with the
appropriate relative magnitude. That is, draw the length of the E vector long wherever the magnitude is large and short wherever
the magnitude is small.
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Electric Field Lines
104. List the three rules for drawing electric fields.
1.
2.
3.
105. What was Faraday’s secret?
106. Several electric field line patterns are shown in the diagrams below. Which of these patterns are incorrect? _________
Explain what is wrong with all incorrect diagrams.
107. Erin Agin drew the following electric field lines for a configuration of two charges.
What did Erin do wrong? Explain.
108. Consider the electric field lines shown in the diagram below. From the diagram, it is apparent that object A is ____ and
object B is ____.
a. +, +
b. -, -
c. +, -
d. -, +
e. insufficient info
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109. Consider the electric field lines drawn at the right for a configuration of two charges. Several locations are labeled on the
diagram. Rank these locations in order of the electric field strength - from
smallest to largest.
110. Use your understanding of electric field lines to identify the charges on the
objects in the following configurations.
111. Observe the electric field lines below for various configurations. Rank the objects according to which has the greatest
magnitude of electric charge, beginning with the smallest charge.
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Electric Fields and Conductors
112. What is a Faraday’s Cage?
113. What are the three charactoristics of an electric field?
114.Suppose that the sphere of a Van de Graaff generator gathers a charge. Then the motor is turned off and the sphere is allowed
to reach electrostatic equilibrium. The charge ___.
a. resides both on its surface and throughout its volume b. resides mostly inside the sphere and only emerges outside when
touched c. resides only on the surface of the sphere
114. Describe the electric field strength at the six labeled locations of the irregularly
shaped, charged object at the right. Use the phrases "zero," "relatively weak," "moderate,"
and relatively strong" as your descriptions.
115. A diagram of an irregularly shaped, charged conductor is shown at the right. Four locations
along the surface are labeled - A, B, C, and D. Rank these locations in increasing order of the
strength of their electric field, beginning with the smallest electric field.
116. Consider the diagram of the thumb tack shown at the right. Suppose that the thumb tack
becomes positively charged. Draw the electric field lines surrounding the thumb tack.
117. Diagram the electric field lines for the following
configuration of two objects. Place arrows on your field
lines.
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118. A favorite physics demonstration used with the Van de Graaff generator involves slowly approaching the dome holding a
paper clip stretched towards the device. Why does the demonstrator not become toast when approaching the machine with the
blunt edge of the paper clip protruding forward?
119. TRUE or FALSE: Lightning rods are placed on homes to protect them from lightning. They work because the electric field
is weak around the lightning rods; thus, there is little flow of charge between the lightning rods/home and the charged clouds.
Lightning
120. What to mechanisms are believed to polarize clouds?
121. How do plasma, step leader and streamers work in a lightening strike?
122. What two things does a lightening rod do to prevent electricity.
123. Which of Franklins’s two theories is concidered to be more accurate?
124. TRUE or FALSE: The presence of lightning rods on top of buildings prevents a cloud with a static charge buildup from
releasing its charge to the building.
125.. TRUE or FALSE: If you place a lightning rod on top of your home but failed to ground it, then it is unlikely that your
home would be struck by lightning.
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