Cutnell/Johnson Physics 8th edition

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Cutnell/JohnsonPhysics 8th edition

• Classroom Response System Questions

Chapter 18 Electric Forces and Electric Fields
Reading Quiz Questions
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18.1.1. Which one of the following values is the
smallest possible amount of free charge that has
been discovered? a) 5.34 ? 10?20 coulombs b)
1.60 ? 10?19 coulombs c) 1.38 ? 10?23
coulombs d) 6.63 ? 10?34 coulombs e) 8.85 ?
10?12 coulombs
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18.1.2. Which one of the following statements
concerning the net electric charge on an object
is true? a) An object with a net negative
charge has an excess number of protons. b) The
net charge can have any value greater than 1.60 ?
10?19 coulombs. c) The net charge on an object
is always a negative number. d) Since protons
are larger, a proton can carry more charge than
an electron. e) The net charge is quantized.
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18.1.3 Which one of the following statements
concerning atoms is false? a) Electrical
charges are uniformly distributed throughout the
volume occupied by an atom. b) The nucleus of
an atom has a positive net electrical charge. c)
Neutrons do not have an electrical charge. d)
Electrons within atoms do not follow discrete
paths or orbits. e) Atoms can lose electrons.
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18.2.1. Complete the following sentence When
animal fur is rubbed along an ebonite rubber rod,
a) The rubber becomes positively charged and
the fur becomes negatively charged. b) The
rubber and the fur become positively charged. c)
The rubber becomes negatively charged and the
fur becomes positively charged. d) The rubber
and the fur become negatively charged. e) The
rubber becomes negatively charged and the fur
remains electrically neutral.
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18.2.2. Which one of the following rules, laws,
or principles describes how the net electric
charge of an isolated system undergoing any
process remains constant? a) Coulombs
principle b) rule of seventy-two c) principle
of electric induction d) law of conservation of
electric charge e) law of triboelectric
synthesis
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18.2.3. Which one of the following statements
concerning the electric force is true? a) Two
charged objects with identical charges will exert
an attractive force on one another. b) It is
possible for a small negatively-charged particle
to float above a negatively charged surface. c)
A positively-charged object is attracted toward
another positively-charged object. d) The
electric force cannot alter the motion of an
object. e) Newtons third law of motion does
not apply to the electrostatic force.
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18.2.4. A charged particle, labeled A, is located
at the midpoint between two other charged
particles, labeled B and C, as shown. The sign
of the charges on all three particles is the
same. When particle A is released, it starts
drifting toward B. What can be determined from
this behavior? a) The charge on A is larger
than the charge on B. b) The charge on A is
larger than the charge on C. c) The charge on C
is larger than the charge on B. d) The charge
on B is larger than the charge on A. e) The
charge on B is larger than the charge on C.
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18.2.5. Which one of the following statements is
a consequence of charge being conserved? a) The
difference between the number of positive and
negative charges does not change for a given
system. b) If you examine a system at different
times, the total number of charges will
change. c) Energy within the system is also
conserved. d) The positive and negative charges
within a system must be quantized. e) The
numbers of electrons and protons for a given
system cannot change.
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18.3.1. Complete the following sentence an
electric insulator has a) the ability to easily
conduct electricity, but does not easily conduct
heat. b) few electrons available to conduct
electricity. c) the ability to easily conduct
electricity and heat. d) no ability to conduct
electricity. e) many free electrons available
to conduct electricity.
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18.3.2. Which one of the following statements
concerning electrical conductors is false? a)
Rubber is an excellent electrical conductor. b)
A material that is a good electrical conductor
has many free electrons that can easily move
around inside the material. c) When a
positively-charged object is moved into contact
with an electrical conductor, electrons move
toward the object. d) Materials that are good
thermal conductors are often good electrical
conductors. e) Most metals are very good
electrical conductors.
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18.3.3. Which of the following terms is used to
describe a material that does not allow electrons
to easily move through it? a) conductor b)
resistor c) transformer d) insulator e)
inductor
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18.4.1. Which of the following statements
describes an object being charged by
induction? a) A glass rod is rubbed with
silk. b) A negatively-charged object is brought
into contact with an initially uncharged
conductor. When they are separated, both objects
are negatively charged. c) A rubber rod is
rubbed with animal fur. d) A positively-charged
object is brought near with an initially
uncharged insulator. The surface of the
insulator becomes slightly negatively
charged. e) As you grab a door knob in the
winter time, you feel a slight electric spark.
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18.4.2. A conductor that is initially
electrically neutral is touched by a rod that has
a net positive charge. Which of the following
statements describing the conductor after the rod
is removed is true? a) The conductor will have
a net positive charge. b) The conductor will
electrically neutral. c) The conductor will
have a net negative charge.
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18.5.1. Two positively charged particles are
separated by a distance r. The force on particle
1 is F due to particle 2. The force on particle
2 is 2F due to particle 1. Is the previous
sentence true or false? Explain why this is the
case. a) The sentence is true, if the net
charge of particle 1 is twice that of particle
2. b) The sentence is false because the forces
on each of the two objects are equal in
magnitude, but opposite in direction. c) The
sentence is true since the particles are
separated by a distance r. d) The sentence is
false because two positively charged particles
cannot exert a force on each other.
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18.5.2. Two positively charged particles are
separated by a distance r. Which of the
following statements concerning the electrostatic
force between acting on each particle due to the
presence of the other is true? a) The
electrostatic force may be calculated using
Faradays law. b) The electrostatic force
depends on the masses of the two particles. c)
The electrostatic force depends on r2. d) The
electrostatic force increases as r is
increased. e) The electrostatic force is on
each particle is directed toward the other
particle.
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18.5.3. Coulombs law is similar to Newtons law
of gravitation in several ways. Which one of the
statements is not a similarity between these two
laws? a) In both laws, the force is inversely
proportional to the square of the distance
between two particles. b) In both laws, the
force decreases with increasing distance between
the two particles. c) In both laws, the force
is proportional to the product of an intrinsic
property of each of the two particles. d) In
both laws, the force is always one of attraction
between the two particles. e) In both laws,
there is a proportionality constant that appears.
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18.6.1. An electron is a negatively charged
particle that has a charge of magnitude, e 1.60
? 10?19 C. Which one of the following statements
best describes the electric field at a distance r
from the electron? a) The electric field is
directed toward the electron and has a magnitude
of ke/r2. b) The electric field is directed
away from the electron and has a magnitude of
ke/r2. c) The electric field is directed toward
the electron and has a magnitude of ke/r. d)
The electric field is directed away from the
electron and has a magnitude of ke/r. e) The
electric field is directed toward the electron
and has a magnitude of ke2/r.
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18.6.2. Which of the following statements
concerning the electric field is false? a) The
SI unit of the electric field is the newton per
meter (N/m) b) The electric field is a vector
quantity. c) At a given point, a charged
particle will experience a force, if an electric
field is present at that location. d) If a
positively-charged particle is placed at a
location where the electric field is directed due
north, it will be accelerated due north. e) The
magnitude of the electric field at a particular
location due to a particular charged particle is
inversely proportional to the distance of the
particle from that location.
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18.6.3. Which of the following combination of
units are those for the strength of the electric
field? a) b) c) d) e)
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18.6.4. The direction of the electric field is
the same as which of the following properties
related to a test charge? a) velocity of the
test charge b) force on a positive test
charge c) acceleration of a negative test
charge d) displacement of a moving test
charge e) None of the above choices are related
to the direction of the electric field.
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18.7.1. Which of the following statements
concerning electric field lines is false? a)
Electric field lines between two charged
particles are often curved. b) Electric field
lines are a method proposed by Michael Faraday to
map the electric field at various locations. c)
Electric field lines can be used to indicate the
local magnitude of the electric field. d)
Electric field lines are always directed radially
away from a positively-charged particle. e) An
electric field line indicates the direction of
the force on an electron placed on the line.
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18.7.2. Consider the following observations (1)
electric field lines are drawn connecting two
point charges labeled A and B, (2) charge A is
due north of charge B, and (3) a proton placed at
the mid-point on a line connecting the two point
charges travels due south. Which one of the
following statements correctly indicates the
signs of the two charges? a) Charge A is
positive and charge B is negative. b) Charge A
is positive and charge B is positive. c) Charge
A is negative and charge B is positive. d)
Charge A is negative and charge B is negative.
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18.7.3. Which one of the following statements
concerning parallel plate capacitors is
false? a) The plates are made from metal. b)
One of the plates has a net positive charge and
one has a net negative charge. c) The electric
field is proportional to the charge per unit
area. d) Electric field lines are directed from
the negative plate to the positive plate. e)
The electric field lines between the plates are
parallel and evenly spaced.
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18.7.4. Complete the following statement
Electric field lines depend on a) the direction
of the electric field. b) the strength of the
electric field. c) the force exerted on a test
charge. d) All of the above choices correctly
complete the statement. e) None of the choices
correctly complete the statement.
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18.7.5. Consider the field lines shown in the
drawing. Which one of the following statements
concerning this situation is true? a) These
field lines are those for a positively charged
particle. b) These field lines are those for a
negatively charged particle. c) These field
lines are those for a positively charged
particle and a negatively charged particle. d)
These field lines are those for two positively
charged particles. e) These field lines are
those for two negatively charged particles.
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18.7.6. Consider the field lines shown in the
drawing. Which one of the following statements
concerning this situation is true? a) A is a
positively charged particle and B is negatively
charged. b) B is a positively charged particle
and A is negatively charged. c) A and B are
both positively charged. d) A and B are both
negatively charged.
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18.9.1. Which of the following laws, principles,
or definitions describes the electric flux
through a surface that encloses a charge? a)
Amontons law b) Gauss law c) Carnots
principle d) definition of a fluxon e)
electric flux principle
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18.9.2. A conducting sphere (shown in grey in the
drawing) of radius R has a number q of excess
electrons distributed uniformly over its surface.
A spherically-shaped Gaussian surface with a
radius r lt R is represented in the drawing by the
dashed circle. Applying Gauss law, what is the
magnitude of the electric field inside the
Gaussian sphere? a) b) c) zero N/C d) e)
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18.9.3. To what does Gauss law relate the
electric field at points on a Gaussian
surface? a) charges near the surface b)
electric field flux leaving the volume enclosed
by the surface c) electric field flux entering
the volume enclosed by the surface d) net
charge enclosed by the surface e) velocity of
charges entering or leaving the surface
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18.10.1. Which of the following properties makes
selenium a useful material in photocopiers? a)
Selenium is opaque and is a good toner
material. b) Selenium is a photoconductor. c)
Selenium always has a net positive charge. d)
Selenium is an electrical insulator when exposed
to light. e) Selenium has a large thermal
conductivity making it better suited for the high
temperature of the toner.
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18.10.2. Which of the following statements best
represents the purpose of the deflection plates
within an inkjet printer? a) The plates control
the direction of ink droplets within the printer.
They are turned on to prevent the ink from
striking the paper. b) The plates control the
direction of electrons within the printer. c)
The plates control the charging of ink droplets.
They are turned on to charge the ink droplets.