Electrical potential energy of systems of charges, conductors and insulators, dielectrics and electric polarization - One Line Questions
1.
What is the potential energy of an electric dipole with dipole moment 'p' in a uniform electric field 'E'? —
-p ⋅ E
2.
If the distance between two charges is doubled, their potential energy changes by a factor of: —
1/4
3.
A material with a very small dielectric constant is likely to be: —
A good insulator
4.
What is a dielectric material? —
An electrical insulator that can be polarized by an applied electric field
5.
What is the permittivity of free space, denoted by ε₀? —
A fundamental constant related to electric fields.
6.
In electrostatic induction, a charged object brought near a conductor causes: —
A redistribution of charges within the conductor.
7.
The potential energy of a system of charges can be negative if: —
There are both positive and negative charges, and attractive forces dominate.
8.
Dielectric polarization results in: —
An induced charge separation within the material.
9.
When a dielectric is placed in an electric field, the molecules of the dielectric align themselves with the field. This phenomenon is called: —
Polarization
10.
The process of inducing a charge in a dielectric by placing it in an electric field is called: —
Polarization
11.
Which of the following materials is typically a good electrical insulator? —
Glass
12.
The dielectric constant (κ) of a material is defined as the ratio of: —
Electric field in vacuum to the electric field in the dielectric.
13.
Which statement is true for a conductor in electrostatic equilibrium? —
Electric field inside is zero.
14.
Which of the following is NOT a property of conductors in electrostatic equilibrium? —
Electric field lines are tangential to the surface.
15.
Which of the following is a characteristic of an insulator? —
Large band gap
16.
Which of the following is a property of insulators? —
Electrons are tightly bound to atoms
17.
In a dielectric material, the electric susceptibility (χe) is a measure of: —
How easily the material can be polarized.
18.
In the absence of an external electric field, what is the potential energy of a conductor? —
Zero
19.
If a system consists of only one charge, its potential energy is: —
Zero
20.
Dielectric strength of a material is the maximum electric field it can withstand before: —
It starts to conduct electricity
21.
What happens to the capacitance of a parallel plate capacitor when a dielectric material is inserted between the plates? —
It increases
22.
When a dielectric material is placed in an external electric field, what is the effect on the field inside the dielectric? —
It decreases
23.
A dielectric material increases the capacitance of a capacitor because: —
It reduces the electric field between the plates for a given charge.
24.
Which of the following is true regarding the potential energy of a system of charges? —
It can be positive, negative, or zero.
25.
What is the electrical potential energy of a system of two point charges, q1 and q2, separated by a distance r? —
k * (q1 * q2) / r
26.
The potential energy of a system of three charges q1, q2, and q3, placed at points A, B, and C respectively, is given by: —
k * (q1*q2/rAB + q2*q3/rBC + q3*q1/rCA)
27.
What is the potential energy of a system of two identical charges 'q' separated by distance 'r'? —
k * q^2 / r
28.
If two charges +q and -q are separated by distance r, their potential energy is: —
-k * q^2 / r
29.
Which of the following best describes an electrical insulator? —
Materials where electrons are tightly bound to their atoms
30.
Which type of material exhibits significant polarization even after the external electric field is removed? —
Ferroelectric material
31.
When a conductor is brought near a charged object, it becomes polarized. The induced charge closest to the charged object is: —
Of the opposite sign to the charged object.
32.
When a dielectric material is subjected to a strong electric field, it can lose its insulating properties. This is known as: —
Dielectric breakdown
33.
In a polarized dielectric, there is a net: —
Net dipole moment
34.
If the potential energy of a system of two charges is zero, it implies: —
The charges are infinitely far apart.
35.
What is electric polarization? —
The separation of positive and negative charges within a material due to an external electric field
36.
What happens to the free electrons in a conductor when an external electric field is applied? —
They redistribute themselves until the net electric field inside is zero
37.
The potential energy of a system of point charges is independent of the order in which the charges are assembled. —
True
38.
For a system of charges, the total potential energy is the algebraic sum of the potential energies of all unique pairs of charges. —
True
39.
When a conductor is placed in an external electric field, the induced charges appear on its surface. —
True, and they create an internal field opposing the external field.
40.
In a conductor, any excess charge resides on the surface. —
True, due to mutual repulsion of charges.
41.
In a conductor, the electric field at the surface is always perpendicular to the surface. —
True, due to the absence of tangential electric field components.
42.
In a conductor, the net electric field inside the material is always zero in electrostatic equilibrium. —
True, due to the free movement of charges.
43.
The electric potential due to a system of point charges is the sum of the potentials due to each individual charge. —
True, due to the principle of superposition.
44.
The work done to assemble a system of n point charges is equal to the potential energy of the system. —
True, it is the sum of the potential energies of all pairs of charges.
45.
In a conductor, the electric potential is constant throughout the volume. —
True, this is a consequence of zero electric field inside.
46.
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. —
True, this is the standard definition.
47.
What is the potential energy of a charge 'q' placed at a point where the electric potential is 'V'? —
q * V
48.
What is the unit of electric potential energy? —
Joule (J)
49.
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? —
Positive
50.
The relative permittivity (εr) of a material is equal to: —
ε / ε₀