Q.1 Coulomb's law is applicable to which type of charges?
Only moving charges
Only stationary charges
Both stationary and moving charges
Only positive charges
Explanation - Coulomb's law describes the electrostatic force between two point charges at rest, not in motion.
Correct answer is: Only stationary charges
Q.2 The unit of electric charge in SI system is:
Coulomb
Ampere
Volt
Ohm
Explanation - The SI unit of electric charge is the Coulomb (C).
Correct answer is: Coulomb
Q.3 Which of the following is true for conductors in electrostatic equilibrium?
Electric field inside is zero
Electric potential is zero inside
Charge resides only at the center
Electric field is uniform inside
Explanation - Inside a conductor at electrostatic equilibrium, the electric field is zero, and charges reside on the surface.
Correct answer is: Electric field inside is zero
Q.4 If the distance between two charges is doubled, the electrostatic force becomes:
Four times
Half
One-fourth
Twice
Explanation - According to Coulomb's law, F ∝ 1/r². Doubling the distance reduces the force to one-fourth.
Correct answer is: One-fourth
Q.5 Which is a vector quantity?
Electric potential
Electric field
Potential energy
Charge
Explanation - Electric field has both magnitude and direction, hence it is a vector quantity.
Correct answer is: Electric field
Q.6 The work done in moving a charge in an electric field depends on:
Path taken
Potential difference
Velocity of the charge
Mass of the charge
Explanation - Work done = qΔV, which depends only on the potential difference, not the path.
Correct answer is: Potential difference
Q.7 The electric field at the surface of a charged conductor is:
Parallel to surface
Perpendicular to surface
Zero
Uniform in space
Explanation - The electric field at the surface of a conductor in equilibrium is perpendicular to the surface.
Correct answer is: Perpendicular to surface
Q.8 Potential energy of a system of two like charges is:
Positive
Negative
Zero
Depends on distance only
Explanation - Like charges repel, so work is needed to bring them closer. Hence, potential energy is positive.
Correct answer is: Positive
Q.9 The SI unit of electric field is:
V/m
N/m
C/m²
J/C
Explanation - Electric field E = F/q = V/m, measured in volts per meter (V/m).
Correct answer is: V/m
Q.10 A parallel plate capacitor has a dielectric inserted between its plates. What happens to its capacitance?
Increases
Decreases
Remains same
Becomes zero
Explanation - Dielectric increases the capacitance by reducing the effective electric field.
Correct answer is: Increases
Q.11 If the charge of a particle is doubled, the force between it and another charge becomes:
Double
Quadruple
Half
Same
Explanation - Coulomb's law: F ∝ q1q2. Doubling one charge doubles the force.
Correct answer is: Double
Q.12 The electric field due to a point charge decreases with distance as:
1/r
1/r²
1/r³
r²
Explanation - Electric field E = kQ/r², decreasing inversely with the square of distance.
Correct answer is: 1/r²
Q.13 Which of the following materials is an insulator?
Copper
Aluminium
Glass
Silver
Explanation - Glass is a poor conductor of electricity and hence an insulator.
Correct answer is: Glass
Q.14 A charged particle is released in a uniform electric field. Its path will be:
Circular
Parabolic
Straight line
Elliptical
Explanation - In a uniform electric field, the force is constant, so acceleration is uniform, resulting in straight-line motion.
Correct answer is: Straight line
Q.15 Gauss's law is useful in finding electric field for:
Point charge
Spherical charge distribution
Infinite plane sheet of charge
All of the above
Explanation - Gauss's law simplifies calculation of electric fields for symmetric charge distributions.
Correct answer is: All of the above
Q.16 The potential at a point due to a point charge is:
Vector quantity
Scalar quantity
Tensor quantity
Zero always
Explanation - Electric potential is a scalar; it has magnitude only, no direction.
Correct answer is: Scalar quantity
Q.17 A charged conductor is placed inside a hollow charged conductor. What is the field inside the hollow cavity?
Zero
Equal to outer charge field
Depends on inner charge
Infinite
Explanation - Inside a hollow conductor at electrostatic equilibrium, the electric field is zero.
Correct answer is: Zero
Q.18 The energy stored in a capacitor is proportional to:
Voltage only
Charge only
Square of voltage
Capacitance only
Explanation - Energy stored, U = 1/2 CV², proportional to the square of voltage.
Correct answer is: Square of voltage
Q.19 A point charge is moved along an equipotential surface. The work done is:
Maximum
Zero
Depends on path
Infinite
Explanation - No work is done along an equipotential because potential difference is zero.
Correct answer is: Zero
Q.20 If the separation between the plates of a parallel plate capacitor is doubled, its capacitance becomes:
Halved
Doubled
Quadrupled
Remains same
Explanation - Capacitance C = ε₀A/d; doubling d halves the capacitance.
Correct answer is: Halved
Q.21 The surface charge density is maximum at:
Flat surface
Sharp point
Center of sphere
Uniform sphere
Explanation - Charge accumulates more at points of high curvature (sharp points).
Correct answer is: Sharp point
Q.22 The electric flux through a closed surface depends on:
Total charge enclosed
Shape of surface
Volume of surface
Surface area only
Explanation - According to Gauss's law, flux depends only on the net charge enclosed, not on shape or size.
Correct answer is: Total charge enclosed
Q.23 If a conductor is charged, the charge resides:
Inside
On the surface
At the center
Uniformly throughout
Explanation - Charges in a conductor at equilibrium move to the surface due to repulsion.
Correct answer is: On the surface
Q.24 A point charge produces an electric field in a medium. If the medium's permittivity increases, the field:
Increases
Decreases
Remains same
Becomes zero
Explanation - Electric field E = Q/(4πεr²); increasing ε reduces the field strength.
Correct answer is: Decreases
Q.25 If two capacitors are connected in series, the equivalent capacitance is:
Sum of individual capacitances
Product/sum formula
Half of larger capacitance
Equal to smaller capacitance
Explanation - For series: 1/C_eq = 1/C1 + 1/C2 + ...
Correct answer is: Product/sum formula