1. Halliday/Resnick/Walker Fundamentals of Physics 8th edition
Classroom Response System Questions
Chapter 24 Electric Potential
Interactive Lecture Questions

2. 24. 2. 1. Two electrons are separated by a distance R
Two electrons are separated by a distance R. If the distance between the charges is increased to 2R, what happens to the total electric potential energy of the system?
a) The total electric potential energy of the system would increase to four times its initial value.
b) The total electric potential energy of the system would increase to two times its initial value.
c) The total electric potential energy of the system would remain the same.
d) The total electric potential energy of the system would decrease to one half its initial value.
e) The total electric potential energy of the system would decrease to one fourth its initial value.

3. 24. 2. 1. Two electrons are separated by a distance R
Two electrons are separated by a distance R. If the distance between the charges is increased to 2R, what happens to the total electric potential energy of the system?
a) The total electric potential energy of the system would increase to four times its initial value.
b) The total electric potential energy of the system would increase to two times its initial value.
c) The total electric potential energy of the system would remain the same.
d) The total electric potential energy of the system would decrease to one half its initial value.
e) The total electric potential energy of the system would decrease to one fourth its initial value.

4. The electric potential energy for two positive charges of magnitude q and separated by a distance r is U1. What will the electric potential energy be if one of the charges is completely removed and replaced by a negative charge of the same magnitude?
a) U2 = 2U1
b) U2 = U1
c) U2 = U1
d) U2 = 2 U1
e) There is no way to determine this without knowing the value of q.

5. The electric potential energy for two positive charges of magnitude q and separated by a distance r is U1. What will the electric potential energy be if one of the charges is completely removed and replaced by a negative charge of the same magnitude?
a) U2 = 2U1
b) U2 = U1
c) U2 = U1
d) U2 = 2 U1
e) There is no way to determine this without knowing the value of q.

6. 24.2.3. Why is an electrostatic force considered a conservative force?
a) Charged particles do not experience friction, which is a non-conservative force.
b) The energy required to move a charged particle around a closed path is equal to zero joules.
c) The work required to move a charged particle from one point to another does not depend upon the path taken.
d) Answers (a) and (b) are both correct.
e) Answers (b) and (c) are both correct.

7. 24.2.3. Why is an electrostatic force considered a conservative force?
a) Charged particles do not experience friction, which is a non-conservative force.
b) The energy required to move a charged particle around a closed path is equal to zero joules.
c) The work required to move a charged particle from one point to another does not depend upon the path taken.
d) Answers (a) and (b) are both correct.
e) Answers (b) and (c) are both correct.

8. A uniform electric field is directed in the negative x direction. If you were to move a positive charge in the positive x direction, how would the total energy of the positive charge / electric field system change, if at all?
a) The total energy of the system would increase.
b) The total energy of the system would decrease.
c) The total energy of the system would remain unchanged.

9. A uniform electric field is directed in the negative x direction. If you were to move a positive charge in the positive x direction, how would the total energy of the positive charge / electric field system change, if at all?
a) The total energy of the system would increase.
b) The total energy of the system would decrease.
c) The total energy of the system would remain unchanged.

10. Which one of the following statements best explains why it is possible to define an electrostatic potential in a region of space that contains an electrostatic field?
a) The work required to bring two charges together is independent of the path taken.
b) A positive charge will gain kinetic energy as it approaches a negative charge.
c) Like charges repel one another and unlike charges attract one another.
d) Work must be done to bring two positive charges closer together.
e) A negative charge will gain kinetic energy as it moves away from another negative charge.

11. Which one of the following statements best explains why it is possible to define an electrostatic potential in a region of space that contains an electrostatic field?
a) The work required to bring two charges together is independent of the path taken.
b) A positive charge will gain kinetic energy as it approaches a negative charge.
c) Like charges repel one another and unlike charges attract one another.
d) Work must be done to bring two positive charges closer together.
e) A negative charge will gain kinetic energy as it moves away from another negative charge.

12. 24. 3. 2. A positive charge is located at the origin
A positive charge is located at the origin. What is the direction of the electric potential of the positive charge?
a) radially outward from the origin
b) radially inward from the origin
c) toward the positive x, y, and z directions
d) toward the negative x, y, and z directions
e) There is no direction since the electric potential is a scalar quantity.

13. 24. 3. 2. A positive charge is located at the origin
A positive charge is located at the origin. What is the direction of the electric potential of the positive charge?
a) radially outward from the origin
b) radially inward from the origin
c) toward the positive x, y, and z directions
d) toward the negative x, y, and z directions
e) There is no direction since the electric potential is a scalar quantity.

14. 24.4.1. Which one of the following statements concerning electrostatic situations is false?
a) No work is required to move a charge along an equipotential surface.
b) If the electric potential with a region of space is zero volts, the electric field within that region must also be zero V/m.
c) If a charge is moved along an equipotential surface, there is no component of the force acting along the charge’s path.
d) The electric field is always perpendicular to equipotential surfaces.
e) The electric field is zero V/m everywhere inside a conductor.

15. 24.4.1. Which one of the following statements concerning electrostatic situations is false?
a) No work is required to move a charge along an equipotential surface.
b) If the electric potential with a region of space is zero volts, the electric field within that region must also be zero V/m.
c) If a charge is moved along an equipotential surface, there is no component of the force acting along the charge’s path.
d) The electric field is always perpendicular to equipotential surfaces.
e) The electric field is zero V/m everywhere inside a conductor.

16. The drawing shows three point charges of equal magnitude, but one is positive (shown in blue) and two are negative (shown in yellow). Some of the equipotential lines surrounding these charges are shown and five are labeled using letters A, B, C, D, and E. At which of the labeled points will an electron have the greatest electric potential energy?
a) A
b) B
c) C
d) D
e) E

17. The drawing shows three point charges of equal magnitude, but one is positive (shown in blue) and two are negative (shown in yellow). Some of the equipotential lines surrounding these charges are shown and five are labeled using letters A, B, C, D, and E. At which of the labeled points will an electron have the greatest electric potential energy?
a) A
b) B
c) C
d) D
e) E

18. The drawing shows three point charges of equal magnitude, but one is positive (shown in blue) and two are negative (shown in yellow). Some of the equipotential lines surrounding these charges are shown and five are labeled using letters A, B, C, D, and E. What is the direction of the electric field at the location of the letter “D?”
a) perpendicular to the
equipotential line marked
“D” and directed toward the
negative charge closest to it
b) parallel to the
location of the letter “C”
c) perpendicular to the
location of the letter “A”
d) toward the negative
charge in the lower part
of the drawing
e) toward the positive charge

19. The drawing shows three point charges of equal magnitude, but one is positive (shown in blue) and two are negative (shown in yellow). Some of the equipotential lines surrounding these charges are shown and five are labeled using letters A, B, C, D, and E. What is the direction of the electric field at the location of the letter “D?”
a) perpendicular to the
equipotential line marked
“D” and directed toward the
negative charge closest to it
b) parallel to the
location of the letter “C”
c) perpendicular to the
location of the letter “A”
d) toward the negative
charge in the lower part
of the drawing
e) toward the positive charge

20. 24. 4. 4. Consider the equipotential lines shown in the box
Consider the equipotential lines shown in the box. The labeled cases
indicate electric field line drawings.
Which of these cases best matches
the equipotential lines shown?
a) 1
b) 2
c) 3
d) 4
e) None of these cases match
the equipotential lines shown.

21. 24. 4. 4. Consider the equipotential lines shown in the box
Consider the equipotential lines shown in the box. The labeled cases
indicate electric field line drawings.
Which of these cases best matches
the equipotential lines shown?
a) 1
b) 2
c) 3
d) 4
e) None of these cases match
the equipotential lines shown.

22. 24.4.5. Consider the equipotential
lines shown in the box. The labeled
cases indicate electric field line
drawings. Which of these cases best
matches the equipotential lines
shown?
a) 1
b) 2
c) 3
d) 4
e) None of these cases match the
equipotential lines shown.

23. 24.4.5. Consider the equipotential
lines shown in the box. The labeled
cases indicate electric field line
drawings. Which of these cases best
matches the equipotential lines
shown?
a) 1
b) 2
c) 3
d) 4
e) None of these cases match the
equipotential lines shown.

24. Consider the four cases shown of a charged particle located some distance from a point P. The quantity of charge and the distances vary. Note that the drawings are not necessarily drawn to scale. Which of the following expressions correctly ranks the electric potential energy at the point P for these four cases?
a) U2 > U1 = U3 = U4
b) U2 > U1 > U3 > U4
c) U2 > U1 > U3 = U4
d) U2 = U1 > U3 = U4
e) U1 = U3 = U4 > U2

25. Consider the four cases shown of a charged particle located some distance from a point P. The quantity of charge and the distances vary. Note that the drawings are not necessarily drawn to scale. Which of the following expressions correctly ranks the electric potential energy at the point P for these four cases?
a) U2 > U1 = U3 = U4
b) U2 > U1 > U3 > U4
c) U2 > U1 > U3 = U4
d) U2 = U1 > U3 = U4
e) U1 = U3 = U4 > U2

26. 24. 7. 1. Consider the four arrangements of three point charges
Consider the four arrangements of three point charges. Rank the values of the total electric potential at point P in each case in descending order (with the largest first).
a) VA > VD > VC > VB
b) VC > VB > VD > VA
c) VC > VD > VA > VB
d) VB > VC > VB > VA
e) VD > VB > VA > VC

27. 24. 7. 1. Consider the four arrangements of three point charges
Consider the four arrangements of three point charges. Rank the values of the total electric potential at point P in each case in descending order (with the largest first).
a) VA > VD > VC > VB
b) VC > VB > VD > VA
c) VC > VD > VA > VB
d) VB > VC > VB > VA
e) VD > VB > VA > VC

28. 24. 7. 2. Two point charges lie along the x axis
Two point charges lie along the x axis. One charge, located at the origin, has a magnitude +2q. The other charge of unknown magnitude and sign is located at x = 5 units. If the electric potential at x = 4 units is equal to zero volts, what is the magnitude and sign of the second point charge?
a) q/2
b) q/4
c) 2q
d) +q/2
e) +2q

29. 24. 7. 2. Two point charges lie along the x axis
Two point charges lie along the x axis. One charge, located at the origin, has a magnitude +2q. The other charge of unknown magnitude and sign is located at x = 5 units. If the electric potential at x = 4 units is equal to zero volts, what is the magnitude and sign of the second point charge?
a) q/2
b) q/4
c) 2q
d) +q/2
e) +2q

30. A proton is moved from point B to point A in an electric field as shown. As a result of its movement, its potential increases to V. If three protons are moved from point B to A, how much will the electric potential of the protons increase?
a) V/9
b) V/3
c) V
d) 3V
e) 9V

31. A proton is moved from point B to point A in an electric field as shown. As a result of its movement, its potential increases to V. If three protons are moved from point B to A, how much will the electric potential of the protons increase?
a) V/9
b) V/3
c) V
d) 3V
e) 9V

32. 24. 8. 1. The drawing shows four points surrounding an electric dipole
The drawing shows four points surrounding an electric dipole. Which one of the following expressions best ranks the electric potential at these four locations?
a) 1 > 2 > 3 > 4
b) 1 > 2 = 4 > 3
c) 3 > 2 > 4 > 1
d) 3 > 2 = 4 > 1
e) 2 = 4 > 1 = 3

33. 24. 8. 1. The drawing shows four points surrounding an electric dipole
The drawing shows four points surrounding an electric dipole. Which one of the following expressions best ranks the electric potential at these four locations?
a) 1 > 2 > 3 > 4
b) 1 > 2 = 4 > 3
c) 3 > 2 > 4 > 1
d) 3 > 2 = 4 > 1
e) 2 = 4 > 1 = 3

34. Consider two conducting spheres with one having a larger radius than the other. Both spheres carry the same amount of excess charge. Which one of the following statements concerning the potential energy of the two spheres is true?
a) The potential energy of the larger sphere is greater than that of the
smaller sphere.
b) The potential energy of the larger sphere is the same as that of the smaller sphere.
c) The potential energy of the larger sphere is less than that of the smaller sphere.

35. Consider two conducting spheres with one having a larger radius than the other. Both spheres carry the same amount of excess charge. Which one of the following statements concerning the potential energy of the two spheres is true?
a) The potential energy of the larger sphere is greater than that of the
smaller sphere.
b) The potential energy of the larger sphere is the same as that of the smaller sphere.
c) The potential energy of the larger sphere is less than that of the smaller sphere.

36. Consider two conducting spheres with one having a larger radius than the other. Both spheres carry the same amount of excess charge. Which one of the following statements concerning the electric potential of the two spheres is true?
a) The electric potential of the larger sphere is greater than that of the smaller sphere.
b) The electric potential of the larger sphere is the same as that of the smaller sphere.
c) The electric potential of the larger sphere is less than that of the smaller sphere.

37. Consider two conducting spheres with one having a larger radius than the other. Both spheres carry the same amount of excess charge. Which one of the following statements concerning the electric potential of the two spheres is true?
a) The electric potential of the larger sphere is greater than that of the smaller sphere.
b) The electric potential of the larger sphere is the same as that of the smaller sphere.
c) The electric potential of the larger sphere is less than that of the smaller sphere.

38. 24. 11. 1. Consider the system shown in the drawing
Consider the system shown in the drawing. A positive charge Q is placed at the center of a hollow conductor that was initially electrically neutral. The arrows are pointing to four locations: (1) a point in the conductor near the outer surface, (2) a point in the hollow space located halfway between the charge Q and the inner surface, (3) a point in the conductor halfway between the inner and outer surfaces, and (4) a point in the conductor near the inner surface. Which of the following choices best ranks the electric potentials at these four locations?
a) 1 = 2 = 3 = 4
b) 2 > 1 = 3 = 4
c) 1 = 3 = 4 > 2
d) 1 > 4 > 3 > 2
e) 2 > 3 > 4 > 1

39. 24. 11. 1. Consider the system shown in the drawing
Consider the system shown in the drawing. A positive charge Q is placed at the center of a hollow conductor that was initially electrically neutral. The arrows are pointing to four locations: (1) a point in the conductor near the outer surface, (2) a point in the hollow space located halfway between the charge Q and the inner surface, (3) a point in the conductor halfway between the inner and outer surfaces, and (4) a point in the conductor near the inner surface. Which of the following choices best ranks the electric potentials at these four locations?
a) 1 = 2 = 3 = 4
b) 2 > 1 = 3 = 4
c) 1 = 3 = 4 > 2
d) 1 > 4 > 3 > 2
e) 2 > 3 > 4 > 1

40. The electric potential of an uncharged, spherical conductor with a radius of 0.1 m is 10 V. If the sphere is located in a region of space with no electric fields, what is the electric potential at a point located 2 m from the center of the sphere?
a) zero volts
b) 2.5 V
c) 5 V
d) 10 V
e) 20 V

41. The electric potential of an uncharged, spherical conductor with a radius of 0.1 m is 10 V. If the sphere is located in a region of space with no electric fields, what is the electric potential at a point located 2 m from the center of the sphere?
a) zero volts
b) 2.5 V
c) 5 V
d) 10 V
e) 20 V