Electrical potential energy of systems of charges, conductors and insulators, dielectrics and electric polarization - Question Bank

1. Which of the following is true regarding the potential energy of a system of charges?
A) It is always positive.
B) It is always negative.
C) It can be positive, negative, or zero.
D) It is equal to the work done by the field.
2. When a conductor is brought near a charged object, it becomes polarized. The induced charge closest to the charged object is:
A) Of the same sign as the charged object.
B) Of the opposite sign to the charged object.
C) Neutral.
D) Zero.
3. The electric potential due to a system of point charges is the sum of the potentials due to each individual charge.
A) True, due to the principle of superposition.
B) False, it is the vector sum.
C) True, but only for charges on a line.
D) False, it is the product of potentials.
4. In a dielectric material, the electric susceptibility (χe) is a measure of:
A) How easily the material conducts electricity.
B) How easily the material can be polarized.
C) The dielectric strength of the material.
D) The resistance to charge flow.
5. What is the potential energy of an electric dipole with dipole moment 'p' in a uniform electric field 'E'?
A) -p ⋅ E
B) p ⋅ E
C) pE sinθ
D) pE cosθ
6. Which type of material exhibits significant polarization even after the external electric field is removed?
A) Non-polar dielectric
B) Conductor
C) Ferroelectric material
D) Insulator
7. The potential energy of a system of point charges is independent of the order in which the charges are assembled.
A) True
B) False, it depends on the order.
C) True, but only if all charges are positive.
D) False, it depends on the path taken.
8. In electrostatic induction, a charged object brought near a conductor causes:
A) A uniform charge distribution on the conductor.
B) A redistribution of charges within the conductor.
C) A permanent charge on the conductor.
D) No change in the conductor's charge distribution.
9. If the potential energy of a system of two charges is zero, it implies:
A) The charges are equal in magnitude and opposite in sign.
B) The charges are infinitely far apart.
C) The charges are identical.
D) One of the charges is zero.
10. Dielectric polarization results in:
A) An induced charge separation within the material.
B) A net movement of charge through the material.
C) A decrease in the material's resistance.
D) The creation of free electrons.
11. What is the work done to move a charge from a point of lower potential to a point of higher potential, assuming no other forces are acting?
A) Zero
B) Negative
C) Positive
D) Depends on the charge magnitude
12. The potential energy of a system of charges can be negative if:
A) All charges are positive.
B) All charges are negative.
C) There are both positive and negative charges, and attractive forces dominate.
D) There are both positive and negative charges, and repulsive forces dominate.
13. A dielectric material increases the capacitance of a capacitor because:
A) It increases the potential difference between the plates.
B) It reduces the electric field between the plates for a given charge.
C) It increases the charge stored on the plates.
D) It increases the distance between the plates.
14. Which of the following is NOT a property of conductors in electrostatic equilibrium?
A) Electric field inside is zero.
B) Potential is constant throughout.
C) Excess charge resides on the surface.
D) Electric field lines are tangential to the surface.
15. If the distance between two charges is doubled, their potential energy changes by a factor of:
A) 2
B) 1/2
C) 4
D) 1/4
16. The relative permittivity (εr) of a material is equal to:
A) ε / ε₀
B) ε₀ / ε
C) 1 / ε₀
D) 1 / ε
17. In a conductor, the electric field at the surface is always perpendicular to the surface.
A) True, due to the absence of tangential electric field components.
B) False, it can have a tangential component.
C) True, but only if the conductor is charged.
D) False, it is parallel to the surface.
18. What is the potential energy of a system of two identical charges 'q' separated by distance 'r'?
A) k * q / r
B) k * q^2 / r^2
C) k * q^2 / r
D) 0
19. When a dielectric material is subjected to a strong electric field, it can lose its insulating properties. This is known as:
A) Polarization
B) Dielectric strength
C) Dielectric breakdown
D) Conduction
20. Which of the following is a property of insulators?
A) High electrical conductivity
B) Free electrons readily available for conduction
C) Electrons are tightly bound to atoms
D) Low resistance
21. For a system of charges, the total potential energy is the algebraic sum of the potential energies of all unique pairs of charges.
A) True
B) False, it's the sum of potentials.
C) False, it's the sum of kinetic energies.
D) False, it's the sum of charges.
22. The process of inducing a charge in a dielectric by placing it in an electric field is called:
A) Conduction
B) Dielectric breakdown
C) Polarization
D) Ionization
23. Which statement is true for a conductor in electrostatic equilibrium?
A) Electric field inside is non-zero.
B) Potential inside is non-zero and constant.
C) Electric field inside is zero.
D) Charge is distributed uniformly throughout the volume.
24. If two charges +q and -q are separated by distance r, their potential energy is:
A) k * q^2 / r
B) -k * q^2 / r
C) k * q^2 / r^2
D) 0
25. What happens to the capacitance of a parallel plate capacitor when a dielectric material is inserted between the plates?
A) It decreases
B) It remains the same
C) It increases
D) It becomes zero
26. In a polarized dielectric, there is a net:
A) Positive charge on the surface facing the positive external field
B) Negative charge on the surface facing the negative external field
C) Net dipole moment
D) Zero net charge
27. The potential energy of a system of charges is the work done by an external agent against the electrostatic forces to bring the charges from infinity to their current positions.
A) True, this is the standard definition.
B) False, it is the work done by the electrostatic forces.
C) True, but only for attractive forces.
D) False, it is related to the electric field, not work done.
28. A material with a very small dielectric constant is likely to be:
A) A good conductor
B) A poor insulator
C) A good insulator
D) A semiconductor
29. What is the unit of electric potential energy?
A) Volt (V)
B) Ampere (A)
C) Joule (J)
D) Coulomb (C)
30. When a conductor is placed in an external electric field, the induced charges appear on its surface.
A) True, and they create an internal field opposing the external field.
B) False, induced charges appear in the interior.
C) True, but they reinforce the external field.
D) False, conductors do not exhibit induced charges.
31. If a system consists of only one charge, its potential energy is:
A) Infinite
B) Zero
C) Equal to the charge itself
D) Depends on the position
32. Dielectric strength of a material is the maximum electric field it can withstand before:
A) It becomes a superconductor
B) It starts to conduct electricity
C) It melts
D) It loses its polarization
33. Which of the following materials is typically a good electrical insulator?
A) Copper
B) Aluminum
C) Glass
D) Graphite
34. In a conductor, the electric potential is constant throughout the volume.
A) True, this is a consequence of zero electric field inside.
B) False, potential varies linearly with distance from the center.
C) True, but only if the conductor is isolated.
D) False, potential is zero everywhere inside.
35. What is the potential energy of a charge 'q' placed at a point where the electric potential is 'V'?
A) V / q
B) q / V
C) q * V
D) q + V
36. The dielectric constant (κ) of a material is defined as the ratio of:
A) Electric field in vacuum to the electric field in the dielectric.
B) Electric field in the dielectric to the electric field in vacuum.
C) Permittivity of the dielectric to the permittivity of free space.
D) Permittivity of free space to the permittivity of the dielectric.
37. What is the permittivity of free space, denoted by ε₀?
A) A measure of how easily a material can be polarized.
B) A fundamental constant related to electric fields.
C) The resistance of a material to electric current.
D) The maximum charge a conductor can hold.
38. In a conductor, any excess charge resides on the surface.
A) True, due to mutual repulsion of charges.
B) False, excess charge is distributed throughout the volume.
C) True, but only for conductors with a cavity.
D) False, excess charge resides at the center.
39. The potential energy of a system of three charges q1, q2, and q3, placed at points A, B, and C respectively, is given by:
A) k * (q1*q2/rAB + q2*q3/rBC + q3*q1/rCA)
B) k * (q1*q2*q3) / (rAB + rBC + rCA)
C) k * (q1/rA + q2/rB + q3/rC)
D) k * (q1*q2 + q2*q3 + q3*q1) / r
40. When a dielectric is placed in an electric field, the molecules of the dielectric align themselves with the field. This phenomenon is called:
A) Conduction
B) Induction
C) Polarization
D) Ionization
41. Which of the following is a characteristic of an insulator?
A) High conductivity
B) Presence of free electrons
C) Large band gap
D) Ability to form electric current easily
42. In a conductor, the net electric field inside the material is always zero in electrostatic equilibrium.
A) True, due to the free movement of charges.
B) False, it is equal to the applied external field.
C) True, but only if the conductor is uncharged.
D) False, it is equal to the surface charge density.
43. The work done to assemble a system of n point charges is equal to the potential energy of the system.
A) True, it is the sum of the potential energies of all pairs of charges.
B) False, it is only the potential energy of the last charge added.
C) True, it is the sum of the potentials at each charge location.
D) False, it is always zero for any system of charges.
44. When a dielectric material is placed in an external electric field, what is the effect on the field inside the dielectric?
A) It increases
B) It remains the same
C) It decreases
D) It becomes zero
45. What is electric polarization?
A) The process of charging an object
B) The separation of positive and negative charges within a material due to an external electric field
C) The flow of electric current through a conductor
D) The reduction of electric resistance in a material
46. What is a dielectric material?
A) A material that conducts electricity very well
B) A material that does not allow electric current to flow
C) An electrical insulator that can be polarized by an applied electric field
D) A material with high conductivity at high temperatures
47. What happens to the free electrons in a conductor when an external electric field is applied?
A) They remain stationary
B) They move towards the positive terminal of the field
C) They move towards the negative terminal of the field
D) They redistribute themselves until the net electric field inside is zero
48. Which of the following best describes an electrical insulator?
A) Materials with free electrons that can move easily
B) Materials where electrons are tightly bound to their atoms
C) Materials that conduct electricity under certain conditions
D) Materials with very low resistance
49. In the absence of an external electric field, what is the potential energy of a conductor?
A) Infinite
B) Zero
C) Depends on the charge distribution
D) Equal to the work done to bring charges to it
50. What is the electrical potential energy of a system of two point charges, q1 and q2, separated by a distance r?
A) k * (q1 * q2) / r^2
B) k * (q1 * q2) / r
C) k * (q1 + q2) / r
D) k * (q1 - q2) / r
All Question Banks
E-Book Electrical potential energy of systems of charges, conductors and insulators, dielectrics and electric polarization One Line Questions Electrical potential energy of systems of charges, conductors and insulators, dielectrics and electric polarization Online Test Electrical potential energy of systems of charges, conductors and insulators, dielectrics and electric polarization