100 Important MCQs (Set-1 of Basic to Moderate MCQs) on Electrostatics, Physics (Unit-Wise MCQs Practice):


This post contains carefully selected Multiple-Choice Questions (MCQs) (Set-1 from Basic to Moderate Level) from Electrostatics of Physics, prepared strictly according to the latest board exam syllabus. These MCQs include a balanced combination of conceptual understanding and numerical problem-solving, making them revision-friendly, exam-oriented, and high-scoring.

Whether you are preparing for annual board examinations, chapter tests, or competitive entry tests, this comprehensive MCQ collection thoroughly covers the fundamental principles of electrostatics—starting from Coulomb’s law (by Charles-Augustin de Coulomb) to Gauss’s law (by Carl Friedrich Gauss)—helping students build strong conceptual clarity and numerical confidence.

This unit-wise MCQ set includes questions from:

• Coulomb’s law and force between point charges in vacuum and media
• Electric field due to a point charge and multiple charges
• Concept of electric field and electric field strength (E = F/q)
• Numerical problems using E=14πε0qr2E = \frac{1}{4\pi\varepsilon_0}\frac{q}{r^2}
• Electric field lines and their graphical representation
• Electric dipole and basic dipole concepts
• Electric flux and flux through closed surfaces
• Statement and applications of Gauss’s law
• Electric field due to infinite charged plates and hollow spherical conductors
• Electric field between oppositely charged parallel plates (including edge effects)
• Electric potential and work done (V = W/q)
• Relationship between electric field and potential (potential gradient)

Each MCQ is provided with the correct answer and a clear, concise explanation, helping students to:

  • Strengthen conceptual understanding of electrostatic phenomena
  • Avoid common mistakes in electric field and potential numericals
  • Improve problem-solving skills involving Coulomb’s law, Gauss’s law, and flux
  • Master diagrams of field lines and charge distributions
  • Achieve maximum marks in the MCQ section

This all-in-one Electrostatics MCQ collection is an essential revision tool for all students aiming to excel in Physics exams and fully master the concepts of electric charges, fields, flux, Gauss’s law, and electric potential.

MCQs No. 1

State Coulomb’s law: The force between two point charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.

a. Force ∝ sum of charges
b. Force ∝ difference of charges
c. Force ∝ product of charges / distance²
d. Force ∝ product of charges × distance

Correct answer: c. Force ∝ product of charges / distance²

Explanation:
Coulomb’s law defines the magnitude of electrostatic force between two point charges as F=kq1q2r2F = k \frac{q_1 q_2}{r^2}.

MCQs. no. 2
If the medium between charges is not free space, the force between them:

a. Increases
b. Decreases
c. Remains same
d. Becomes zero

Correct answer: b. Decreases

Explanation:
Force is reduced by the relative permittivity of the medium: F=14πεq1q2r2F = \frac{1}{4 \pi \varepsilon} \frac{q_1 q_2}{r^2} 

MCQs. no. 3
The electric field at a distance r from a point charge q is:

a. E=qrE = \frac{q}{r}

b. E=14πε0qr2E = \frac{1}{4 \pi \varepsilon_0} \frac{q}{r^2}

c. E=q4πrE = \frac{q}{4 \pi r}

d. E=q4r2E = \frac{q}{4 r^2}

Correct answer: b. E=14πε0qr2E = \frac{1}{4 \pi \varepsilon_0} \frac{q}{r^2}

Explanation:
Electric field is force per unit charge: E=F/qE = F/q , derived from Coulomb’s law.

MCQs. no. 4
Electric field strength is defined as:

a. Force per unit charge
b. Work per unit charge
c. Potential energy per unit charge
d. Charge per unit area

Correct answer: a. Force per unit charge

Explanation:
By definition, E=F/qE = F/q. It represents the force experienced by a positive test charge.

MCQs. no. 5
Unit of electric field in SI system is:

a. Volt
b. Coulomb
c. Newton per Coulomb
d. Joule

Correct answer: c. Newton per Coulomb

Explanation:
Electric field E=F/qE = F/q has SI unit N/C.

MCQs. no. 6
Potential difference between two points is defined as:

a. Force per unit charge
b. Work done in moving unit positive charge
c. Energy per unit mass
d. Power per unit charge

Correct answer: b. Work done in moving unit positive charge

Explanation:
Potential difference V=W/qV = W/q. It measures energy change per unit charge.

MCQs. no. 7
Electric flux through a closed surface enclosing charge Q is:

a. Φ=Q\Phi = Q 
b. Φ=Q/ε0\Phi = Q/\varepsilon_0
c. Φ=0\Phi = 0 
d. Φ=ε0/Q\Phi = \varepsilon_0/Q 

Correct answer: b. Φ=Q/ε0\Phi = Q/\varepsilon_0

Explanation:
Gauss’s law states that total flux through a closed surface equals the charge enclosed divided by permittivity.

MCQs. no. 8
The electric field inside a hollow spherical conductor is:

a. Maximum
b. Zero
c. Equal to surface field
d. Infinite

Correct answer: b. Zero

Explanation:
Charges reside on the outer surface; the net electric field inside is zero (electrostatic shielding).

MCQs. no. 9
Potential at the center of a uniformly charged spherical shell is:

a. Zero
b. Maximum
c. Equal to surface potential
d. Depends on radius only

Correct answer: c. Equal to surface potential

Explanation:
Potential inside a spherical shell is constant and equal to the potential at the surface.

MCQs. no. 10
A dipole consists of:

a. Two equal charges of same sign
b. Two equal and opposite charges separated by a distance
c. Two unequal charges
d. Any two charges

Correct answer: b. Two equal and opposite charges separated by a distance

Explanation:
A dipole has zero net charge but a defined dipole moment p=q×2ap = q \times 2a .

MCQs. no. 11
Electric field along the axial line of a dipole is:

a. Zero
b. Maximum
c. Minimum
d. Constant

Correct answer: b. Maximum

Explanation:
Along the axial line, fields due to both charges add in same direction → maximum field.

MCQs. no. 12
Electric field along the equatorial line of a dipole is:

a. Maximum
b. Minimum
c. Zero
d. Constant

Correct answer: b. Minimum

Explanation:
On equatorial line, contributions from charges partially cancel → smaller net E.

MCQs. no. 13
Potential at midpoint of a dipole is:

a. Maximum
b. Minimum
c. Zero
d. Depends on distance

Correct answer: c. Zero

Explanation:
Potential is a scalar quantity; contributions from equal and opposite charges cancel at midpoint.

MCQs. no. 14
Capacitance of a parallel plate capacitor depends on:

a. Charge and voltage
b. Area of plates and separation
c. Material of wires
d. Shape of circuit

Correct answer: b. Area of plates and separation

Explanation:
C = ε₀A/d. Larger area → more capacitance; larger distance → less capacitance.

MCQs. no. 15
Inserting a dielectric into a charged capacitor:

a. Decreases capacitance
b. Increases capacitance
c. Has no effect
d. Discharges capacitor

Correct answer: b. Increases capacitance

Explanation:
Dielectric reduces effective field, allowing more charge storage → higher capacitance.

MCQs. no. 16
Energy stored in a capacitor is:

a. U = QV
b. U = ½ C V²
c. U = CV²
d. U = ½ QV²

Correct answer: b. U = ½ C V²

Explanation:
Energy is stored in electric field; formula derived from work done to charge capacitor.

MCQs. no. 17
Potential difference across a charged capacitor is:

a. V = C/Q
b. V = Q/C
c. V = ½ Q/C
d. V = Q²/C

Correct answer: b. V = Q/C

Explanation:
Voltage is proportional to charge and inversely proportional to capacitance.

MCQs. no. 18
Gauss’s law can be applied to:

a. Flat surfaces only
b. Curved surfaces only
c. Any closed surface
d. Open surfaces

Correct answer: c. Any closed surface

Explanation:
Gauss’s law applies to any closed surface, regardless of shape.

MCQs. no. 19
Electric field between two oppositely charged infinite parallel plates is:

a. Zero
b. Uniform in center, fringing at edges
c. Maximum at edges
d. Non-uniform everywhere

Correct answer: b. Uniform in center, fringing at edges

Explanation:
Field lines are parallel in center → uniform; bend near edges → fringing.

MCQs. no. 20
Electric potential energy of two charges q₁ and q₂ separated by r:

a. U = k q₁ q₂ / r
b. U = q₁ q₂ r
c. U = k q₁ q₂ r²
d. U = k q₁ q₂

Correct answer: a. U = k q₁ q₂ / r

Explanation:
Work done to assemble charges is stored as potential energy.

MCQs. no. 21

If two charges are doubled and distance is halved, the force between them:

a. Doubles
b. Quadruples
c. Becomes 16 times
d. Remains same

Correct answer: c. Becomes 16 times

Explanation:
Coulomb’s law: F∝q1q2/r2F \propto q_1 q_2 / r^2 . Doubling charges → 4×, halving distance → 4×, total → 16×.

MCQs. no. 22
Work done in moving a charge in a uniform electric field over distance d is:

a. W = F/d
b. W = F × d
c. W = F² × d
d. W = F/d²

Correct answer: b. W = F × d

Explanation:
Work done = Force × displacement in direction of force.

MCQs. no. 23
Unit of electric potential is:

a. Coulomb
b. Volt
c. Newton
d. Ampere

Correct answer: b. Volt

Explanation:
1 Volt = 1 Joule per Coulomb (V = W/q).

MCQs. no. 24
Electric field at the surface of a conductor in electrostatic equilibrium is:

a. Zero
b. Perpendicular to surface
c. Parallel to surface
d. Maximum inside conductor

Correct answer: b. Perpendicular to surface

Explanation:
In equilibrium, charges move to make the field zero inside; surface field is perpendicular.

MCQs. no. 25
Potential inside a conductor in electrostatic equilibrium is:

a. Zero
b. Same as surface potential
c. Depends on shape
d. Maximum at center

Correct answer: b. Same as surface potential

Explanation:
Potential is constant throughout a conductor in electrostatic equilibrium.

MCQs. no. 26
A uniform electric field does positive work on a positive charge when it moves:

a. Against the field
b. Along the field
c. Perpendicular to the field
d. Circular path

Correct answer: b. Along the field

Explanation:
Work = F × displacement × cosθ; θ = 0° along field → maximum work.

MCQs. no. 27
The dipole moment of an electric dipole is:

a. p=q/dp = q / d 
b. p=q×2ap = q × 2a 
c. p=q×r2p = q × r^2 
d. p=q/2ap = q / 2a 

Correct answer: b. p=q×2ap = q × 2a 

Explanation:
Dipole moment = magnitude of charge × separation between charges.

MCQs. no. 28
Torque on an electric dipole in uniform electric field is:

a. τ=pEsin⁡θτ = pE \sinθ 
b. τ=pEcos⁡θτ = pE \cosθ 
c. τ=E/pτ = E/p 
d. τ=0τ = 0 

Correct answer: a. τ=pEsin⁡θτ = pE \sinθ 

Explanation:
Torque tends to align dipole along field; depends on angle between p and E.

MCQs. no. 29
Potential at a point on the equatorial line of a dipole is:

a. Maximum
b. Minimum
c. Zero
d. Depends on separation

Correct answer: c. Zero

Explanation:
Potentials from equal and opposite charges cancel at equatorial points.

MCQs. no. 30
Capacitor stores energy in the form of:

a. Magnetic field
b. Electric field
c. Kinetic energy
d. Thermal energy

Correct answer: b. Electric field

Explanation:
Energy is stored in the field between the plates: U=12CV2U = \frac12 C V^2 .

MCQs. no. 31
The direction of electric field is:

a. From negative to positive charge
b. From positive to negative charge
c. Circular around charge
d. Random

Correct answer: b. From positive to negative charge

Explanation:
By convention, E points in the direction a positive test charge would move.

MCQs. no. 32
Electric field inside a conductor is zero because:

a. Charges move freely
b. Field is always perpendicular
c. Charges are fixed
d. Potential is zero

Correct answer: a. Charges move freely

Explanation:
Free electrons move to cancel any internal field → E = 0.

MCQs. no. 33
Electric field due to a point charge is a:

a. Vector quantity
b. Scalar quantity
c. Always zero
d. Circular field

Correct answer: a. Vector quantity

Explanation:
It has both magnitude and direction; direction along line joining charge and point.

MCQs. no. 34
Work done in moving a charge along an equipotential surface is:

a. Maximum
b. Zero
c. Depends on field
d. Infinite

Correct answer: b. Zero

Explanation:
No potential difference → no work done.

MCQs. no. 35
Electric field between two oppositely charged plates is:

a. Non-uniform
b. Uniform
c. Zero
d. Maximum at edges

Correct answer: b. Uniform

Explanation:
Parallel plates produce nearly uniform field in the central region.

MCQs. no. 36
Gauss’s law relates:

a. Electric flux and field strength
b. Electric flux and enclosed charge
c. Electric flux and potential difference
d. None of these

Correct answer: b. Electric flux and enclosed charge

Explanation:
Total flux through closed surface = Q_enclosed / ε₀.

MCQs. no. 37
For a point charge, electric field decreases with:

a. Distance
b. Distance squared
c. Distance cubed
d. Charge

Correct answer: b. Distance squared

Explanation:
From Coulomb’s law: E ∝ 1/r².

MCQs. no. 38
Potential due to a point charge decreases with:

a. Distance
b. Distance squared
c. Inverse of distance
d. Charge

Correct answer: c. Inverse of distance

Explanation:
V = kq/r → decreases linearly with r.

MCQs. no. 39
Dielectric constant of a medium is:

a. Ratio of field in vacuum to field in medium
b. Product of fields
c. Always zero
d. Inversely proportional to charge

Correct answer: a. Ratio of field in vacuum to field in medium

Explanation:
E_medium = E_vacuum / K → reduces effective field.

MCQs. no. 40
Energy density in an electric field is:

a. u=12ε0E2u = \frac12 \varepsilon_0 E^2 
b. u=12CV2u = \frac12 C V^2 
c. u=QVu = QV 
d. u=12q2/Cu = \frac12 q^2/C 

Correct answer: a. u=12ε0E2u = \frac12 \varepsilon_0 E^2 

Explanation:
Energy per unit volume stored in electric field = ½ ε₀ E².

Electrostatics MCQs (41–60)

MCQs. no. 41
A hollow spherical conductor has a charge Q. The electric field:

a. Is maximum at the center
b. Is zero inside the sphere
c. Is uniform inside
d. Increases linearly inside

Correct answer: b. Is zero inside the sphere

Explanation:
Charges reside on the outer surface; by Gauss’s law, E = 0 inside a hollow conductor.

MCQs. no. 42
Electric field due to an infinite plane sheet of charge is:

a. Zero
b. Uniform and perpendicular to the sheet
c. Decreases with distance
d. Radial

Correct answer: b. Uniform and perpendicular to the sheet

Explanation:
By Gauss’s law, E = σ / (2ε₀), independent of distance.

MCQs. no. 43
Electric flux through a closed surface depends on:

a. Shape of the surface
b. Total charge enclosed
c. Electric field outside
d. Both a and c

Correct answer: b. Total charge enclosed

Explanation:
Gauss’s law: Flux = Q_enclosed / ε₀, independent of surface shape.

MCQs. no. 44
Unit of electric flux is:

a. N/C
b. N·m²/C
c. V/m
d. C/m²

Correct answer: b. N·m²/C

Explanation:
Φ = E·A cosθ; SI unit = N·m²/C.

MCQs. no. 45
Potential difference between two points is defined as:

a. Work done per unit charge to move from one point to another
b. Force per unit charge
c. Charge per unit field
d. Field per unit distance

Correct answer: a. Work done per unit charge to move from one point to another

Explanation:
V = W/q, by definition of electric potential.

MCQs. no. 46
Work done moving a charge along an equipotential surface is:

a. Maximum
b. Zero
c. Depends on field
d. Negative

Correct answer: b. Zero

Explanation:
Potential difference along equipotential = 0 → W = 0.

MCQs. no. 47
Electric field is related to potential by:

a. E = -dV/dr
b. E = V²
c. E = V/q
d. E = V·q

Correct answer: a. E = -dV/dr

Explanation:
Electric field is the negative gradient of potential.

MCQs. no. 48
In a parallel plate capacitor with dielectric, the capacitance:

a. Decreases
b. Increases
c. Remains same
d. Becomes zero

Correct answer: b. Increases

Explanation:
Dielectric reduces effective field → more charge stored → higher capacitance: C = K·C₀.

MCQs. no. 49
Two equal positive charges are placed at a distance. Electric field at midpoint is:

a. Zero
b. Maximum
c. Directed along line joining charges
d. Directed perpendicular to line

Correct answer: a. Zero

Explanation:
Fields due to equal charges cancel at midpoint → net E = 0.

MCQs. no. 50
Two charges of equal magnitude but opposite signs are placed. Field at midpoint is:

a. Zero
b. Maximum, directed from + to -
c. Maximum, directed along line perpendicular to charges
d. Infinite

Correct answer: b. Maximum, directed from + to -

Explanation:
Fields due to opposite charges reinforce at midpoint.

MCQs. no. 51
Potential at the midpoint of two equal and opposite charges (electric dipole) is:

a. Zero
b. Maximum
c. Minimum
d. Depends on separation

Correct answer: a. Zero

Explanation:
Potentials from +q and -q cancel → V = 0.

MCQs. no. 52
Torque on an electric dipole in uniform electric field is maximum when:

a. Dipole parallel to field
b. Dipole perpendicular to field
c. Dipole at 45° to field
d. Zero

Correct answer: b. Dipole perpendicular to field

Explanation:
τ = pE sinθ; maximum when sinθ = 1 → θ = 90°.

MCQs. no. 53
Energy stored in a charged capacitor is:

a. ½ CV²
b. CV²
c. ½ QV
d. Both a and c

Correct answer: d. Both a and c

Explanation:
U = ½ CV² = ½ QV, equivalent expressions.

MCQs. no. 54
Potential energy of a system of two point charges is:

a. PE = k q₁ q₂ / r
b. PE = k q₁ q₂ r
c. PE = k (q₁ + q₂)/r
d. PE = q/r

Correct answer: a. PE = k q₁ q₂ / r

Explanation:
Electrostatic potential energy = work done to assemble the charges.

MCQs. no. 55
Electric field intensity is:

a. Force per unit charge
b. Work per unit charge
c. Energy per unit charge
d. Potential per unit charge

Correct answer: a. Force per unit charge

Explanation:
E = F/q, by definition of electric field.

MCQs. no. 56
A positive test charge moves from lower to higher potential. Work done by the field is:

a. Positive
b. Negative
c. Zero
d. Infinite

Correct answer: b. Negative

Explanation:
Field points from high → low potential. Work against field is negative.

MCQs. no. 57
Coulomb’s law is not applicable for:

a. Point charges
b. Stationary charges
c. Moving charges at relativistic speeds
d. Charges in vacuum

Correct answer: c. Moving charges at relativistic speeds

Explanation:
At high speeds, magnetic effects and relativity must be considered.

MCQs. no. 58
Electric field due to a line charge decreases with:

a. Distance
b. Distance²
c. Distance³
d. Independent of distance

Correct answer: a. Distance

Explanation:
E for infinite line: E = λ / (2πε₀ r) → decreases linearly with r.

MCQs. no. 59
Potential due to infinite line of charge:

a. V ∝ ln r
b. V ∝ 1/r
c. V ∝ r²
d. V = constant

Correct answer: a. V ∝ ln r

Explanation:
Derived by integration along radial distance from line charge.

MCQs. no. 60
Electric field between two oppositely charged infinite plates is independent of:

a. Surface area
b. Charge density
c. Distance between plates (approx.)
d. Dielectric constant

Correct answer: c. Distance between plates (approx.)

Explanation:
Field E ≈ σ / ε₀; uniform and nearly independent of separation for infinite plates.

MCQs. no. 61

The unit of electric dipole moment is:

a. C·m²
b. C/m
c. C·m
d. N·m

Correct answer: c. C·m

Explanation:
Dipole moment p = q × d, where q is charge and d is separation → unit is coulomb-meter (C·m).

MCQs. no. 62
The electric field at a point on the axial line of a dipole is:

a. E = k·2p / r³
b. E = k·p / r²
c. E = k·p / r³
d. E = k·p / r⁴

Correct answer: a. E = k·2p / r³

Explanation:
Derived from superposition of two point charges along the dipole axis.

MCQs. no. 63
Electric field at a point on the equatorial line of a dipole is:

a. E = k·2p / r³
b. E = k·p / r³
c. E = k·p / r²
d. E = k·p / r⁴

Correct answer: b. E = k·p / r³

Explanation:
Equatorial line field is perpendicular to the dipole axis; derived from vector sum of point charges.

MCQs. no. 64
If the distance between two point charges is doubled, the force between them:

a. Doubles
b. Halves
c. Becomes one-fourth
d. Becomes four times

Correct answer: c. Becomes one-fourth

Explanation:
Coulomb’s law: F ∝ 1/r² → F_new = F/4 when r → 2r.

MCQs. no. 65
Electric field intensity due to a point charge at distance r is:

a. E = kq / r²
b. E = kq / r
c. E = kq / r³
d. E = kq·r

Correct answer: a. E = kq / r²

Explanation:
By definition, E = F/q; using Coulomb’s law, F = kq₁q₂ / r².

MCQs. no. 66
Electric potential at a distance r from a point charge q is:

a. V = kq / r
b. V = kq / r²
c. V = kq·r
d. V = kq·r²

Correct answer: a. V = kq / r

Explanation:
Potential is work done per unit charge to bring it from infinity to r.

MCQs. no. 67
Two point charges of equal magnitude q but opposite signs separated by distance 2a form a dipole. Dipole moment is:

a. q / 2a
b. q·a
c. q·2a
d. q²·a

Correct answer: c. q·2a

Explanation:
Dipole moment p = charge × separation → p = q × 2a.

MCQs. no. 68
The work done in moving a charge along an equipotential is:

a. Maximum
b. Zero
c. Depends on path
d. Depends on charge

Correct answer: b. Zero

Explanation:
Along equipotential, ΔV = 0 → W = qΔV = 0.

MCQs. no. 69
If a positive charge is released in a uniform electric field, it will:

a. Move opposite to field
b. Move along field
c. Remain stationary
d. Move randomly

Correct answer: b. Move along field

Explanation:
Force on positive charge F = qE, in direction of E.

MCQs. no. 70
Electric potential energy of two point charges q₁ and q₂ separated by r is:

a. U = k·q₁q₂ / r
b. U = k·q₁q₂·r
c. U = k·q₁q₂ / r²
d. U = k·q₁q₂·r²

Correct answer: a. U = k·q₁q₂ / r

Explanation:
Electrostatic potential energy = work done to bring charges from infinity.

MCQs. no. 71
For a conductor in electrostatic equilibrium, electric field inside is:

a. Zero
b. Maximum
c. Uniform
d. Non-uniform

Correct answer: a. Zero

Explanation:
Charges move to surface → no net field inside conductor.

MCQs. no. 72
Potential difference between the plates of a parallel plate capacitor is V. Energy stored is:

a. U = ½ CV²
b. U = CV²
c. U = CV
d. U = V² / 2C

Correct answer: a. U = ½ CV²

Explanation:
Work done to charge capacitor: U = ½ QV = ½ CV².

MCQs. no. 73
In a parallel plate capacitor, increasing distance between plates:

a. Increases capacitance
b. Decreases capacitance
c. No change
d. Doubles energy

Correct answer: b. Decreases capacitance

Explanation:
C = ε₀A/d → capacitance inversely proportional to plate separation.

MCQs. no. 74
Electric field between two oppositely charged infinite plates is:

a. Non-uniform
b. Uniform
c. Zero
d. Radial

Correct answer: b. Uniform

Explanation:
Infinite plates produce uniform field E = σ / ε₀.

MCQs. no. 75
Electric field lines:

a. Never cross
b. Can cross
c. Are always curved
d. Always form circles

Correct answer: a. Never cross

Explanation:
Field at a point has unique direction → lines cannot intersect.

MCQs. no. 76
Electric field at the center of a uniformly charged ring:

a. Maximum
b. Zero
c. Depends on radius
d. Infinite

Correct answer: b. Zero

Explanation:
Symmetry → net field contributions cancel at center.

MCQs. no. 77
For a point outside a uniformly charged spherical shell, the shell behaves like:

a. Point charge at center
b. Infinite sheet
c. Hollow tube
d. Dipole

Correct answer: a. Point charge at center

Explanation:
By Gauss’s law, field outside shell is as if all charge at center.

MCQs. no. 78
Force between two charges in a medium with permittivity ε is:

a. F = q₁q₂ / (4πεr²)
b. F = q₁q₂ / (4πε₀r²)
c. F = q₁q₂ / (2πεr²)
d. F = q₁q₂ / (πεr²)

Correct answer: a. F = q₁q₂ / (4πεr²)

Explanation:
Coulomb’s law in medium: force decreases by factor ε (permittivity).

MCQs. no. 79
Capacitance of a parallel plate capacitor depends on:

a. Area of plates and separation
b. Charge only
c. Potential difference only
d. Material outside capacitor

Correct answer: a. Area of plates and separation

Explanation:
C = ε₀·A/d; increases with area, decreases with separation.

MCQs. no. 80
Electric field intensity at a distance r from a charged conducting sphere:

a. Zero outside sphere
b. Same as point charge at center
c. Varies nonlinearly
d. Maximum inside sphere

Correct answer: b. Same as point charge at center

Explanation:
Sphere behaves like point charge outside → E = kQ/r².

MCQs. no. 81

Electric flux through a closed surface depends on:

a. Shape of surface only
b. Charge enclosed only
c. Medium only
d. Charge enclosed and medium

Correct answer: d. Charge enclosed and medium

Explanation:
By Gauss’s law, Φ = q_enclosed / ε → depends on total enclosed charge and permittivity of medium.

MCQs. no. 82
Gauss’s law is applicable for:

a. Only curved surfaces
b. Only flat surfaces
c. Any closed surface
d. Open surfaces

Correct answer: c. Any closed surface

Explanation:
Law relates total electric flux through closed surface to total charge enclosed.

MCQs. no. 83
Inside a hollow charged conductor, the electric field is:

a. Maximum
b. Uniform
c. Zero
d. Varies linearly

Correct answer: c. Zero

Explanation:
Charges reside on outer surface → no net field inside conductor.

MCQs. no. 84
The direction of electric field is defined as the direction of:

a. Negative test charge movement
b. Positive test charge movement
c. Electron flow
d. Current flow

Correct answer: b. Positive test charge movement

Explanation:
By convention, E points along force on a positive charge.

MCQs. no. 85
Potential gradient is defined as:

a. ΔV / Δr
b. -ΔV / Δr
c. Δr / ΔV
d. ΔV × Δr

Correct answer: b. -ΔV / Δr

Explanation:
Electric field E = -dV/dr → negative gradient of potential.

MCQs. no. 86
Unit of electric flux in SI system is:

a. N·C⁻¹
b. N·m²·C⁻¹
c. C/m²
d. V/m

Correct answer: b. N·m²·C⁻¹

Explanation:
Φ = E·A·cosθ → unit of E × area = N/C × m² = N·m²·C⁻¹.

MCQs. no. 87
In a parallel plate capacitor with dielectric, capacitance:

a. Decreases
b. Increases
c. Remains same
d. Becomes zero

Correct answer: b. Increases

Explanation:
Dielectric reduces effective field → C = κC₀, where κ > 1.

MCQs. no. 88
Electric field at a point due to two equal and opposite charges at a point equidistant from both is:

a. Zero
b. Maximum
c. Same as individual charge
d. Undefined

Correct answer: a. Zero

Explanation:
Net field is vector sum → equal and opposite → cancels.

MCQs. no. 89
Work done in moving a charge along electric field lines:

a. Zero
b. Maximum
c. Depends on potential difference
d. Negative

Correct answer: c. Depends on potential difference

Explanation:
W = qΔV → work done depends on potential difference between initial and final points.

MCQs. no. 90
Potential difference between plates of a capacitor is 10 V. If charge is doubled, energy stored:

a. Doubles
b. Quadruples
c. Halves
d. Remains same

Correct answer: b. Quadruples

Explanation:
U = ½ QV → doubling Q while V constant → U = 4 × original.

MCQs. no. 91
Superposition principle is used to calculate:

a. Electric field due to single charge
b. Net electric field due to multiple charges
c. Electric potential only
d. Capacitance

Correct answer: b. Net electric field due to multiple charges

Explanation:
Field at a point is vector sum of fields due to all individual charges.

MCQs. no. 92
A point charge +q is placed at origin. Electric field at a point on x-axis at distance r is:

a. E = kq / r², along x-axis
b. E = kq / r³, along y-axis
c. E = kq / r², opposite x-axis
d. Zero

Correct answer: a. E = kq / r², along x-axis

Explanation:
By Coulomb’s law, along line joining point and charge.

MCQs. no. 93
Potential energy of a system of two point charges depends on:

a. Only charge magnitude
b. Only distance between charges
c. Both charge magnitude and separation
d. Neither

Correct answer: c. Both charge magnitude and separation

Explanation:
U = k q₁q₂ / r → depends on both.

MCQs. no. 94
Capacitor stores energy in the form of:

a. Kinetic energy
b. Magnetic energy
c. Electric potential energy
d. Thermal energy

Correct answer: c. Electric potential energy

Explanation:
Energy stored = ½ CV², present in the electric field between plates.

MCQs. no. 95
Electric field due to infinite sheet of charge is:

a. Zero
b. Uniform and perpendicular
c. Radial
d. Varies inversely with distance

Correct answer: b. Uniform and perpendicular

Explanation:
By symmetry, E = σ / 2ε₀ constant at all points near sheet.

MCQs. no. 96
Electric field inside a uniformly charged solid sphere at distance r from center:

a. E = kQ / r²
b. E = kQr / R³
c. Zero
d. E = kQ / R²

Correct answer: b. E = kQr / R³

Explanation:
From Gauss’s law, only the charge enclosed within radius r contributes.

MCQs. no. 97
Electric field inside a conductor in electrostatic equilibrium:

a. Maximum at center
b. Zero
c. Uniform and non-zero
d. Varies linearly

Correct answer: b. Zero

Explanation:
Charges reside on surface → field inside conductor cancels.

MCQs. no. 98
If charge q is increased in a capacitor at fixed voltage, stored energy:

a. Decreases
b. Increases
c. Remains same
d. Becomes zero

Correct answer: b. Increases

Explanation:
U = ½ QV → energy increases with Q.

MCQs. no. 99
Direction of electric field due to dipole at a point on equatorial plane is:

a. Along dipole axis
b. Perpendicular to dipole axis
c. Radial
d. Zero

Correct answer: b. Perpendicular to dipole axis

Explanation:
Vector sum of fields from positive and negative charges → along equatorial direction.

MCQs. no. 100
Unit of electric potential in SI system is:

a. Joule
b. Volt
c. Coulomb
d. Newton

Correct answer: b. Volt

Explanation:
V = W/q → work done per unit charge = volt (V).