Electric potential for point charge and dipole, potential difference, equipotential surfaces - Question Bank

1. For a system of charges, the electric potential at a point is the work done per unit charge in bringing the test charge from infinity to that point, assuming all other charges are fixed. This statement is true due to the principle of:
A) Conservation of energy
B) Superposition of potentials
C) Gauss's law
D) Newton's third law
2. The electric potential at a distance r from a point charge q is V = kq/r. If the charge q is positive, V is:
A) Positive and decreases with r
B) Positive and increases with r
C) Negative and decreases with r
D) Negative and increases with r
3. If a charge is moved from a point of lower potential to a point of higher potential, the potential energy of the charge:
A) Decreases
B) Increases
C) Remains constant
D) Becomes zero
4. The potential difference between two points is related to the electric field E and displacement dr by:
A) dV = -E.dr
B) dV = E.dr
C) dV = -E/dr
D) dV = E/dr
5. For an electric dipole, the potential at a point on the perpendicular bisector (equatorial line) is:
A) Maximum
B) Minimum
C) Zero
D) Non-zero and variable
6. Which of the following correctly describes an equipotential surface?
A) A surface where the electric field is constant.
B) A surface where the electric potential is constant.
C) A surface where the electric field lines are parallel.
D) A surface where the electric charge is uniformly distributed.
7. If the potential at a point is 10 V, and a charge of 5 C is brought from infinity to this point, the work done by the external agent is:
A) 50 J
B) 2 J
C) 10 J
D) 5 J
8. For a positive point charge, the potential decreases as the distance from the charge:
A) Decreases
B) Increases
C) Remains the same
D) Becomes zero
9. What is the electric potential at infinity from a point charge?
A) Infinite
B) Zero
C) Depends on the charge
D) Depends on the distance
10. The potential difference between two points in an electric field is defined as:
A) The work done by the field per unit charge.
B) The work done against the field per unit charge.
C) The total charge between the points.
D) The electric field strength.
11. An equipotential surface is a surface where the electric potential is:
A) Maximum
B) Minimum
C) Zero
D) The same at all points
12. Which of the following statements about potential difference is correct?
A) It is the work done per unit charge to move a charge from infinity to a point.
B) It is the work done per unit charge to move a charge between two points.
C) It is the energy required to create a charge.
D) It is the total charge in a region.
13. Consider two point charges +q and -q separated by a distance d. The electric potential at a point far away from the dipole on its axis is proportional to:
A) 1/r
B) 1/r^2
C) 1/r^3
D) r
14. If the electric field is zero in a region, then the electric potential in that region must be:
A) Zero
B) Constant
C) Maximum
D) Minimum
15. The potential energy of an electric dipole (p) in an electric field (E) is given by:
A) -p.E
B) p.E
C) -p x E
D) p x E
16. If the electric potential at a point is V, and the distance from a point charge q is r, then the electric field E at that point is given by:
A) E = V/r
B) E = V*r
C) E = -dV/dr
D) E = -dr/dV
17. Which of the following is NOT an equipotential surface for a single point charge?
A) A sphere centered on the charge
B) A plane perpendicular to the line joining the charge to another charge
C) A plane passing through the charge
D) A surface of constant distance from the charge
18. For an isolated positive point charge, the electric potential varies with distance 'r' as:
A) V ∝ 1/r
B) V ∝ 1/r^2
C) V ∝ r
D) V ∝ r^2
19. The electric potential at a point P is V. If a charge of -q is brought to P from infinity, the work done by an external agent is:
A) Vq
B) -Vq
C) V/q
D) -V/q
20. An electric dipole is placed in a uniform external electric field. The net force on the dipole is:
A) Always zero
B) Non-zero and depends on orientation
C) Always maximum
D) Always minimum
21. The electric potential inside a hollow conducting sphere with a charge on it is:
A) Variable, decreasing with distance from the center
B) Constant and equal to the potential at the surface
C) Zero everywhere
D) Increasing with distance from the center
22. A sphere of radius R has a charge Q uniformly distributed over its surface. The electric potential at any point inside the sphere is:
A) Zero
B) KQ/R
C) KQ/r (where r is distance from center)
D) KQ/R^2
23. The potential difference between two points in an electric field is independent of:
A) The starting point
B) The ending point
C) The path taken between the points
D) The magnitude of the charge moved
24. Two points A and B are at the same electric potential. If a charge is moved from A to B, the work done by the electric field is:
A) Positive
B) Negative
C) Zero
D) Infinite
25. Which of the following is a scalar quantity?
A) Electric field
B) Electric force
C) Electric potential
D) Electric displacement
26. The electric potential at a point P due to a point charge q at origin is V. If the charge is doubled and the distance is halved, the new potential will be:
A) V/4
B) V/2
C) 2V
D) 4V
27. If we move a positive charge against the direction of the electric field, the potential energy:
A) Increases
B) Decreases
C) Remains constant
D) Becomes zero
28. The electric potential at a point due to a dipole depends on:
A) Distance from the dipole only
B) Angle with the dipole axis only
C) Magnitude of the dipole moment only
D) Distance, angle, and dipole moment
29. What is the potential difference between the center and a point at infinity from a point charge q?
A) kq/infinity
B) kq/0
C) kq/r
D) Zero
30. If V is the electric potential and q is the charge, the potential energy (U) of the charge is given by:
A) U = V/q
B) U = q/V
C) U = qV
D) U = V + q
31. Consider a region with a uniform electric field E. The equipotential surfaces in this region are:
A) Spheres centered at the origin
B) Concentric cylinders
C) Parallel planes perpendicular to the field lines
D) A single point
32. A charge of +5 microcoulomb is placed at the origin. The electric potential at a point (3, 4) meters from the origin is:
A) 1500 V
B) 1000 V
C) 900 V
D) 1200 V
33. The relationship between electric field (E) and electric potential (V) is given by:
A) E = -dV/dr
B) E = dV/dr
C) E = -dV/dt
D) E = dV/dt
34. If V(x) = 5x^2 + 3, what is the electric field component Ex at x=2?
A) -10 V/m
B) 10 V/m
C) -20 V/m
D) 20 V/m
35. The electric potential due to an electric dipole on its axial line at a distance 'r' from the center is approximately:
A) kP/r
B) kP/r^2
C) kP/r^3
D) Zero
36. The electric potential due to an electric dipole on its equatorial line at a distance 'r' from the center is:
A) Zero
B) kP/r^2
C) kP/r
D) Infinite
37. Which of the following statements about equipotential surfaces is INCORRECT?
A) They are closer together where the electric field is stronger.
B) They are further apart where the electric field is weaker.
C) They can intersect each other.
D) They are always perpendicular to electric field lines.
38. An equipotential surface is a surface over which the electric potential is:
A) Uniformly distributed
B) Constant
C) Zero
D) Maximum
39. What is the potential difference between two points if the work done to move a charge of 2 C is 4 J?
A) 0.5 V
B) 2 V
C) 4 V
D) 8 V
40. The potential due to a negative point charge at a distance 'r' is:
A) Positive and decreasing with distance
B) Negative and decreasing with distance
C) Positive and increasing with distance
D) Negative and increasing with distance
41. For a system of 'n' point charges, the total electric potential at a point is the algebraic sum of the potentials due to individual charges. This is due to the principle of:
A) Superposition
B) Conservation of charge
C) Gauss's Law
D) Equipotential surfaces
42. If the electric potential decreases as we move away from a positive point charge, it implies:
A) The potential is increasing
B) The potential is decreasing
C) The potential is constant
D) The potential is zero
43. The potential difference between two points is defined as the work done per unit charge in moving a charge from one point to the other.
A) Against the electric field
B) Along the electric field
C) Between any two points
D) In the direction of the electric field
44. Work done in moving a charge between two points on the same equipotential surface is:
A) Positive
B) Negative
C) Zero
D) Infinite
45. Electric field lines are always perpendicular to:
A) Electric field lines themselves
B) Magnetic field lines
C) Equipotential surfaces
D) Conductors
46. The locus of points in an electric field where the electric potential is constant is called:
A) Electric field line
B) Electric flux line
C) Equipotential surface
D) Magnetic field line
47. What is the electric potential at the center of an electric dipole?
A) Zero
B) Maximum
C) Minimum
D) Infinite
48. An electric dipole consists of two:
A) Equal and opposite charges separated by a small distance
B) Equal and like charges separated by a small distance
C) Unequal and opposite charges separated by a small distance
D) Equal and opposite charges placed at the same point
49. The electric potential at a distance 'r' from a point charge 'q' is given by:
A) V = kq/r
B) V = kq^2/r
C) V = kq/r^2
D) V = k q^2/r^2
50. What is the SI unit of electric potential?
A) Ampere
B) Volt
C) Ohm
D) Farad
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