CBSE Class 12th Physics Electrostatic Potential and Capacitance 100 MCQs

Physics – Electrostatic Potential and Capacitance

Class 12 Physics (Chapter 2) • 100 Multiple Choice Questions

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Question 1

What is the SI unit of electrostatic potential?

Correct Answer: Volt (V)

Question 2

Electrostatic potential is a:

Correct Answer: Scalar quantity

Question 3

The electrostatic potential at a distance r from a point charge q is proportional to:

Correct Answer: 1/r

Question 4

The work done in moving a test charge over an equipotential surface is:

Correct Answer: Zero

Question 5

Electric field lines are always _____ to an equipotential surface.

Correct Answer: Perpendicular (normal)

Question 6

The relation between electric field E and potential V is:

Correct Answer: E = -dV/dr

Question 7

Potential energy of a system of two point charges q₁ and q₂ separated by distance r is:

Correct Answer: U = (1 / 4πε₀) * (q₁q₂ / r)

Question 8

What is the electrostatic potential inside a charged hollow spherical conductor?

Correct Answer: Constant and equal to that at the surface

Question 9

What is the electric field inside a charged hollow spherical conductor?

Correct Answer: Zero

Question 10

The SI unit of capacitance is:

Correct Answer: Farad (F)

Question 11

Capacitance of a parallel plate capacitor is given by:

Correct Answer: C = ε₀ A / d

Question 12

When a dielectric slab of dielectric constant K is inserted between the plates of a parallel plate capacitor, its capacitance:

Correct Answer: Increases by a factor K

Question 13

Energy stored in a capacitor of capacitance C and potential V is given by:

Correct Answer: U = ½ CV²

Question 14

When capacitors are connected in series, the equivalent capacitance is:

Correct Answer: Less than the smallest individual capacitance

Question 15

When capacitors are connected in parallel, the equivalent capacitance is:

Correct Answer: Equal to the sum of individual capacitances

Question 16

Dielectric polarization results in:

Correct Answer: Creation of an internal electric field opposite to external field

Question 17

Polar molecules are those in which:

Correct Answer: Center of positive and negative charges do not coincide

Question 18

Non-polar molecules have:

Correct Answer: Zero permanent dipole moment

Question 19

Van de Graaff generator is a device used for:

Correct Answer: Generating high high-voltage / high electric potential

Question 20

Electrostatic potential energy density in an electric field E is given by:

Correct Answer: ½ ε₀ E²

Question 21

The electric potential due to an electric dipole at an axial point varies with distance r as:

Correct Answer: 1/r²

Question 22

The electrostatic potential due to an electric dipole at any point on its equatorial line is:

Correct Answer: Zero

Question 23

Dimensional formula of electric potential is:

Correct Answer: [M L² T⁻³ A⁻¹]

Question 24

Dimensional formula of capacitance is:

Correct Answer: [M⁻¹ L⁻² T⁴ A²]

Question 25

1 electron volt (eV) is equal to:

Correct Answer: 1.6 × 10⁻¹⁹ Joules

Question 26

The capacity of an isolated spherical conductor of radius R is proportional to:

Correct Answer: R

Question 27

If three capacitors of capacitances C₁, C₂, and C₃ are connected in series, the net capacitance C is given by:

Correct Answer: 1/C = 1/C₁ + 1/C₂ + 1/C₃

Question 28

If two capacitors are in parallel, the total capacitance is:

Correct Answer: C₁ + C₂

Question 29

When a capacitor is charged by a battery, energy is stored in:

Correct Answer: The electric field between the plates

Question 30

What happens to the energy stored in a capacitor if the potential difference across it is doubled?

Correct Answer: Becomes four times

Question 31

If a dielectric slab is inserted into a charged capacitor while the battery remains disconnected, which of the following remains constant?

Correct Answer: Charge (Q)

Question 32

If a dielectric slab is inserted into a capacitor while the battery remains connected, which of the following remains constant?

Correct Answer: Potential difference (V)

Question 33

The electric potential at the center of a square of side a carrying equal charges q at its four corners is:

Correct Answer: 4√2 q / (4πε₀ a)

Question 34

The electric field at the center of the same square carrying equal positive charges q at all four corners is:

Correct Answer: Zero

Question 35

Equipotential surfaces for a uniform electric field are:

Correct Answer: Planes perpendicular to the electric field directions

Question 36

Equipotential surfaces for a point charge are:

Correct Answer: Concentric spheres centered at the charge

Question 37

Two equipotential surfaces can never intersect because:

Correct Answer: Electric field would have two directions at the intersection point

Question 38

The potential energy of an electric dipole of dipole moment p in an electric field E is given by:

Correct Answer: -p · E

Question 39

What is the electric potential at the surface of a charged spherical shell of radius R and charge Q?

Correct Answer: Q / (4πε₀ R)

Question 40

If two conducting spheres of different radii are connected by a thin wire, they will come to the same:

Correct Answer: Electric potential

Question 41

Polarization vector P is defined as:

Correct Answer: Dipole moment per unit volume

Question 42

Dielectric constant K is related to electric susceptibility χe as:

Correct Answer: K = 1 + χe

Question 43

A capacitor of capacitance C is charged to potential V and then disconnected. If its plates are pulled apart, the potential difference:

Correct Answer: Increases

Question 44

What happens to the stored energy of a disconnected charged capacitor when its plates are pulled apart?

Correct Answer: Increases

Question 45

Common potential when two charged conductors of capacities C₁, C₂ and potentials V₁, V₂ are connected together is:

Correct Answer: (C₁V₁ + C₂V₂) / (C₁ + C₂)

Question 46

Loss of energy when two charged conductors are joined together is due to:

Correct Answer: Heat and sparking across connecting wires

Question 47

What is the electric potential energy of a single point charge q in an external electric field V(r)?

Correct Answer: q · V(r)

Question 48

The electric field inside a dielectric slab when placed in an external electric field E₀ becomes:

Correct Answer: E₀ / K

Question 49

The electric potential at any point due to an electric dipole is proportional to:

Correct Answer: Cos θ / r²

Question 50

Which of the following quantity is zero inside a charged conducting sphere?

Correct Answer: Electric field

Question 51

The work done in bringing a unit positive charge from infinity to a point in an electric field is called:

Correct Answer: Electrostatic potential at that point

Question 52

The potential at a point due to a positive charge is:

Correct Answer: Positive

Question 53

The potential at a point due to a negative charge is:

Correct Answer: Negative

Question 54

Electric potential energy of a system of charges depends on:

Correct Answer: Relative positions of the charges

Question 55

The unit of electric potential gradient is:

Correct Answer: Volt/meter (V/m)

Question 56

Electrostatic force is conservative, which means:

Correct Answer: Work done in a closed path is zero

Question 57

If a unit positive charge is taken from one point to another over an equipotential surface, the work done is:

Correct Answer: Zero

Question 58

The capacitance of a capacitor does NOT depend on:

Correct Answer: Charge on the capacitor

Question 59

The electric potential at a point due to a charge q at distance r is V. If the charge is doubled and distance is also doubled, the potential becomes:

Correct Answer: V (remains same)

Question 60

What is the net electric field inside a conductor placed in an external electrostatic field?

Correct Answer: Zero

Question 61

Which of the following is true for an uncharged conductor in an electric field?

Correct Answer: Potential is constant throughout the volume of the conductor

Question 62

A capacitor stores energy in the form of:

Correct Answer: Electrostatic energy

Question 63

If n identical capacitors each of capacitance C are connected in parallel, the equivalent capacitance is:

Correct Answer: nC

Question 64

If n identical capacitors each of capacitance C are connected in series, the equivalent capacitance is:

Correct Answer: C / n

Question 65

The electric potential at a distance r from the center of an electric dipole varies as:

Correct Answer: 1/r²

Question 66

Polarization of a dielectric material is proportional to:

Correct Answer: Applied electric field

Question 67

The unit of polarization vector P is:

Correct Answer: C/m²

Question 68

What happens to the electric potential energy of two like charges when they are brought closer together?

Correct Answer: Increases

Question 69

What happens to the electric potential energy of two unlike charges when they are brought closer together?

Correct Answer: Decreases

Question 70

The dimensional formula of energy density of an electric field is:

Correct Answer: [M L⁻¹ T⁻²]

Question 71

If a charged capacitor is disconnected from the battery and its plates are brought closer, the potential difference across the plates:

Correct Answer: Decreases

Question 72

The electric field just outside the surface of a charged conductor is directed:

Correct Answer: Normal to the surface

Question 73

Which of the following devices is used to store electrical energy?

Correct Answer: Capacitor

Question 74

The dielectric strength of a medium refers to:

Correct Answer: Maximum electric field the medium can withstand without breakdown

Question 75

The unit of dielectric strength is:

Correct Answer: Volt/meter (V/m)

Question 76

If a dielectric slab is partially inserted into a parallel plate capacitor, it experiences a force that pulls it:

Correct Answer: Inside the capacitor

Question 77

The electric potential at distance r from the center, outside a charged spherical shell, is given by:

Correct Answer: Q / (4πε₀ r)

Question 78

The potential due to a collection of point charges is equal to:

Correct Answer: Algebraic sum of potentials due to individual charges

Question 79

Equipotential surfaces are closer together in regions of:

Correct Answer: Strong electric field

Question 80

Equipotential surfaces are farther apart in regions of:

Correct Answer: Weak electric field

Question 81

Which of the following is correct for a capacitor of capacitance C connected across voltage V?

Correct Answer: Q = C V

Question 82

If the area of plates of a parallel plate capacitor is doubled and the distance is halved, the capacitance becomes:

Correct Answer: Four times

Question 83

The electric potential at the center of an electric dipole is:

Correct Answer: Zero

Question 84

A parallel plate capacitor has capacitance C. If a metal sheet of thickness t (t < d) is inserted between the plates, the new capacitance:

Correct Answer: Increases

Question 85

The energy stored in a capacitor can also be expressed as:

Correct Answer: Q² / (2C)

Question 86

Van de Graaff generator works on the phenomenon of:

Correct Answer: Action of sharp points (corona discharge) and electrostatic induction

Question 87

What is the dimensional formula of electric potential energy?

Correct Answer: [M L² T⁻²]

Question 88

The potential at infinity is conventionally taken as:

Correct Answer: Zero

Question 89

When a dielectric is placed in an electric field, the net electric field inside the dielectric:

Correct Answer: Decreases

Question 90

The capacitance of a spherical conductor of radius 1 meter in vacuum is approximately:

Correct Answer: 1.11 × 10⁻¹⁰ Farad

Question 91

Which of the following is an example of a polar molecule?

Correct Answer: HCl (Hydrochloric acid)

Question 92

Which of the following is an example of a non-polar molecule?

Correct Answer: H₂ (Hydrogen)

Question 93

The electric potential inside a solid conducting sphere of radius R carrying charge Q is:

Correct Answer: Equal to the potential at the surface (Q / 4πε₀ R)

Question 94

If the distance between plates of a parallel plate capacitor is halved, its capacitance:

Correct Answer: Doubles

Question 95

The electric potential due to a point charge is positive if the charge is:

Correct Answer: Positive

Question 96

The potential energy stored per unit volume in an electric field is known as:

Correct Answer: Electrostatic energy density

Question 97

Which of the following units is equivalent to Volt?

Correct Answer: Joule/Coulomb (J/C)

Question 98

If a dielectric is inserted into a capacitor connected across a battery, the energy stored in the capacitor:

Correct Answer: Increases by a factor K

Question 99

The direction of electric field at any point is in the direction of:

Correct Answer: Steepest decrease of electric potential

Question 100

What is the net electric flux through a closed surface enclosing an electric dipole?

Correct Answer: Zero