Chapter 22

Halliday/Resnick/Walker

Fundamentals of Physics 8th edition

Classroom Response System Questions

Chapter 22 Electric Fields

Reading Quiz Questions

22.2.1. Which one 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.

22.2.1. Which one 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.

22.2.2. Which of the following combination of units are those for the

strength of the electric field?

a)

b)

c)

d)

e)

2

2

kg m

C s

N m

C

kg m

C s

N

C

C m

s

22.2.2. Which of the following combination of units are those for the

strength of the electric field?

a)

b)

c)

d)

e)

2

2

kg m

C s

N m

C

kg m

C s

N

C

C m

s

22.2.3. Which one of the following statements best describes the concept of the

electric field?

a) The electric field is a vector quantity that is the reaction force of electrons.

b) The electric field at each point is the potential energy of a test charge divided

by the amount of the test charge.

c) The electric field is a distribution of vectors at points due to the presence of

one or more charged objects.

d) The electric field is a scalar quantity related to the total amount of charge on


e) The electric field is a scalar field, which has a magnitude at each given point,

similar to the temperature or pressure field.

22.2.3. Which one of the following statements best describes the concept of the

electric field?

a) The electric field is a vector quantity that is the reaction force of electrons.

b) The electric field at each point is the potential energy of a test charge divided

by the amount of the test charge.

c) The electric field is a distribution of vectors at points due to the presence of


d) The electric field is a scalar quantity related to the total amount of charge on


e) The electric field is a scalar field, which has a magnitude at each given point,

similar to the temperature or pressure field.

22.3.1. 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.

22.3.1. 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.

22.3.2. 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.

22.3.2. 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.

22.3.3. 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.

22.3.3. 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.

22.3.4. 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.

22.3.4. 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.

22.4.1. 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.

22.4.1. 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.

22.4.2. 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


d) These field lines are those for two

positively charged particles.

e) These field lines are those for two negatively charged particles.

22.4.2. 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


c) These field lines are those for a

positively charged particle and a


d) These field lines are those for two

positively charged particles.

e) These field lines are those for two negatively charged particles.

22.4.3. 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.

22.4.3. 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.

22.5.1. Which one of the following expressions gives the correct

relationship between the electric field strength E and the distance r

from an electric dipole?

a)

b)

c)

d)

e)

1E

r

2

1E

r

3

1E

r

E r

2E r

22.5.1. Which one of the following expressions gives the correct

relationship between the electric field strength E and the distance r

from an electric dipole?

a)

b)

c)

d)

e)

1E

r

2

1E

r

3

1E

r

E r

2E r

22.5.2. Why does the electric field due to a dipole decrease more

rapidly with increasing distance than that for a single charge?

a) The two charges in the dipole are separated by some distance.

b) Because there are two charges in the dipole, the electric field has

one-half the field strength of a single charge.

c) Any given point is closer to one of the charges of the dipole than to

the other.

d) The total charge of the dipole is neutral (zero).

e) Dipoles do not produce a significant electric field.

22.5.2. Why does the electric field due to a dipole decrease more

rapidly with increasing distance than that for a single charge?

a) The two charges in the dipole are separated by some distance.

b) Because there are two charges in the dipole, the electric field has

one-half the field strength of a single charge.

c) Any given point is closer to one of the charges of the dipole than to

the other.

d) The total charge of the dipole is neutral (zero).

e) Dipoles do not produce a significant electric field.

22.5.3. Which one of the following statements concerning the electric dipole

moment is false?

a) The dipole moment is a scalar quantity.

b) The dipole moment has units of C m.

c) The dipole moment combines two intrinsic properties of an electric

dipole, the distance between the charges and the amount of charge on

each object.

d) The dipole moment is directed from the negative charge toward the

positive charge of the dipole.

e) The direction of the dipole moment is used to specify the orientation of

the dipole.

22.5.3. Which one of the following statements concerning the electric dipole

moment is false?

a) The dipole moment is a scalar quantity.

b) The dipole moment has units of C m.

c) The dipole moment combines two intrinsic properties of an electric

dipole, the distance between the charges and the amount of charge on

each object.

d) The dipole moment is directed from the negative charge toward the

positive charge of the dipole.

e) The direction of the dipole moment is used to specify the orientation of

the dipole.

22.6.1. Consider the following hypothetical situation: An infinitely

long line of charge is located along the central axis of an infinitely

long hollow cylinder of charge. Which of the following statements

concerning the force on the line of charge is true?

a) The force on the line of charge is infinite.

b) The force on the line of charge is zero newtons.

c) The force depends on the radius of the cylinder. It will be larger if

the cylinder radius is large.

d) The force depends on the radius of the cylinder. It will be smaller

if the cylinder radius is large.

22.6.1. Consider the following hypothetical situation: An infinitely

long line of charge is located along the central axis of an infinitely

long hollow cylinder of charge. Which of the following statements

concerning the force on the line of charge is true?

a) The force on the line of charge is infinite.

b) The force on the line of charge is zero newtons.

c) The force depends on the radius of the cylinder. It will be larger if

the cylinder radius is large.

d) The force depends on the radius of the cylinder. It will be smaller

if the cylinder radius is large.

22.6.2. Which one of the following statements concerning charge

distributions is false?

a) Charge distributions consist of a very large number of closely spaced

charges.

b) Charge distributions may be uniform arrangements of charges along a

line, over a surface, or throughout a volume.

c) Calculus provides important tools for determining electric fields due to

charge distributions.

d) Charge distributions are treated as being composed of discrete charges.

e) In dealing with charge distributions, it is often more useful to speak in

terms of a charge density rather than the total charge.

22.6.2. Which one of the following statements concerning charge

distributions is false?

a) Charge distributions consist of a very large number of closely spaced

charges.

b) Charge distributions may be uniform arrangements of charges along a

line, over a surface, or throughout a volume.

c) Calculus provides important tools for determining electric fields due to

charge distributions.

d) Charge distributions are treated as being composed of discrete charges.

e) In dealing with charge distributions, it is often more useful to speak in

terms of a charge density rather than the total charge.

22.6.3. Consider the drawing which shows a uniform ring of charge of radius R.

Which of the following expressions gives the correct dependence of the

electric field at point P located on the z axis, where z >> R?

a)

b)

c)

d)

e)

1E

z

2

1E

z

3

1E

z

E z

2E z

22.6.3. Consider the drawing which shows a uniform ring of charge of radius R.

Which of the following expressions gives the correct dependence of the

electric field at point P located on the z axis, where z >> R?

a)

b)

c)

d)

e)

1E

z

2

1E

z

3

1E

z

E z

2E z

22.7.1. Which of the following expressions gives the electric field due to an infinite

sheet of charge with a uniform charge density ?

a)

b)

c)

d)

e)

2E

r

22E

r

30

2E

r

02E

2

0

E r

22.7.1. Which of the following expressions gives the electric field due to an infinite

sheet of charge with a uniform charge density ?

a)

b)

c)

d)

e)

2E

r

22E

r

30

2E

r

02E

2

0

E r

22.8.1. Two positively charged particles are in fixed locations on the x axis. A test charge

that is free to move about the x-y plane is placed at the mid-point between the two

positively charged particles. If the test charge is held stationary at the mid-point and

then released, it remains stationary. Which of the following is the best explanation

for this behavior?

a) The test charge is at a point of stable equilibrium for both the x and y directions.

b) The test charge is at a point of stable equilibrium for the x direction, but not for the y

direction.

c) The test charge is at a point of stable equilibrium for the y direction, but not for the x

direction.

d) The test charge is at a point of unstable equilibrium for both the x direction and the y

direction.

e) No forces are acting on the test charge.

22.8.1. Two positively charged particles are in fixed locations on the x axis. A test charge

that is free to move about the x-y plane is placed at the mid-point between the two

positively charged particles. If the test charge is held stationary at the mid-point and

then released, it remains stationary. Which of the following is the best explanation

for this behavior?

a) The test charge is at a point of stable equilibrium for both the x and y directions.

b) The test charge is at a point of stable equilibrium for the x direction, but not for the y

direction.

c) The test charge is at a point of stable equilibrium for the y direction, but not for the x

direction.

d) The test charge is at a point of unstable equilibrium for both the x direction and the y

direction.

e) No forces are acting on the test charge.

22.9.1. A dipole is located within a uniform electric field and aligned perpendicular to the

field. Why is the electrostatic potential energy is equal to zero joules in this

situation?

a) There is no force acting on the dipole. Only a torque is acting on it.

b) There is no torque acting on the dipole when the dipole is parallel or antiparallel to the

field, so when the dipole is perpendicular, the potential energy must be zero joules.

c) Because the zero potential energy position is arbitrary, you may choose it to be

anything.

d) If the dipole is parallel or antiparallel to the electric field it must have correspondingly

opposite signs, therefore when it is perpendicular to the field, the energy must be zero

joules.

e) Dipoles have no interaction with electric fields since their net charge is zero coulombs,

so the potential energy is always zero joules.

22.9.1. A dipole is located within a uniform electric field and aligned perpendicular to the

field. Why is the electrostatic potential energy is equal to zero joules in this

situation?

a) There is no force acting on the dipole. Only a torque is acting on it.

b) There is no torque acting on the dipole when the dipole is parallel or antiparallel to the

field, so when the dipole is perpendicular, the potential energy must be zero joules.

c) Because the zero potential energy position is arbitrary, you may choose it to be

anything.

d) If the dipole is parallel or antiparallel to the electric field it must have correspondingly

opposite signs, therefore when it is perpendicular to the field, the energy must be zero

joules.

e) Dipoles have no interaction with electric fields since their net charge is zero coulombs,

so the potential energy is always zero joules.

22.9.2. Consider the dipole shown in a uniform electric field. Which of the

following occurs as the dipole aligns itself with the electric field?

a) The electric field breaks the dipole

into two separate charges.

b) The total energy of the dipole and

electric field decreases.

c) The potential energy of the electric

field and the dipole does not change.

d) The potential energy of the electric

field and the dipole increases.

e) The potential energy of the electric field and the dipole decreases.

22.9.2. Consider the dipole shown in a uniform electric field. Which of the

following occurs as the dipole aligns itself with the electric field?

a) The electric field breaks the dipole

into two separate charges.

b) The total energy of the dipole and

electric field decreases.

c) The potential energy of the electric

field and the dipole does not change.

d) The potential energy of the electric

field and the dipole increases.

e) The potential energy of the electric field and the dipole decreases.