Q.1 Two point charges of +2 μC and -3 μC are placed 0.5 m apart. What is the magnitude of the force between them?
2.16 N
0.216 N
21.6 N
0.0216 N
Explanation - Using Coulomb's law: F = k * |q1*q2| / r^2 = (9x10^9)*(2x10^-6*3x10^-6)/(0.5^2) = 21.6 N.
Correct answer is: 21.6 N
Q.2 What is the unit of electric field intensity?
Newton
Volt/meter
Coulomb
Joule
Explanation - Electric field E = F/q, its SI unit is N/C which is equivalent to V/m (Volt per meter).
Correct answer is: Volt/meter
Q.3 If a charge is doubled and distance between charges is halved, how does the force change?
4 times
8 times
2 times
16 times
Explanation - F ∝ q1*q2 / r^2. Doubling charges (q1*q2 → 4q^2) and halving distance (1/r^2 → 4) gives F new = 4*4 = 16 times.
Correct answer is: 16 times
Q.4 The electric field at the center of a uniformly charged ring of radius R is:
Zero
kQ/R^2
kQ/2R^2
kQ/R
Explanation - By symmetry, the horizontal components cancel, leaving no net field at the center of a uniformly charged ring.
Correct answer is: Zero
Q.5 Which of the following statements is true about conductors in electrostatic equilibrium?
Electric field inside is maximum
Electric field inside is zero
Surface charge density is zero
Charges move freely inside
Explanation - In electrostatic equilibrium, the electric field inside a conductor is zero, and charges reside on the surface.
Correct answer is: Electric field inside is zero
Q.6 What is the electric potential at infinity due to a point charge Q?
Zero
Q
kQ
Infinite
Explanation - By definition, the electric potential at infinity is taken as zero.
Correct answer is: Zero
Q.7 Two equal positive charges are placed 1 m apart. At what point is the net electric field zero?
Midpoint
Closer to one charge
Outside the line joining them
No such point exists between them
Explanation - For two like charges, the electric field cannot be zero anywhere between them; it is zero at a point outside the line joining them, beyond the charges.
Correct answer is: No such point exists between them
Q.8 The SI unit of electric potential is:
Volt
Joule
Coulomb
Newton
Explanation - Electric potential is energy per unit charge, V = W/Q. Its SI unit is Volt (V).
Correct answer is: Volt
Q.9 If the distance between two charges is doubled, the force between them becomes:
Halved
Quartered
Doubled
Unchanged
Explanation - Coulomb's law: F ∝ 1/r^2, so doubling distance → F new = F/4.
Correct answer is: Quartered
Q.10 Which configuration produces a uniform electric field?
Point charge
Infinite plane sheet of charge
Ring of charge
Spherical shell
Explanation - An infinite plane sheet of charge produces a uniform electric field perpendicular to the sheet, independent of distance.
Correct answer is: Infinite plane sheet of charge
Q.11 Electric field inside a hollow charged conductor is:
Zero
Maximum at center
Depends on shape
Non-zero constant
Explanation - Gauss's law: the net electric field inside a hollow conductor is zero regardless of its shape.
Correct answer is: Zero
Q.12 A test charge experiences a force in an electric field because:
It has mass
It has charge
It is moving
It has potential energy
Explanation - Electric force acts on charged particles; mass or motion is irrelevant for force due to the field.
Correct answer is: It has charge
Q.13 The potential energy of two point charges separated by distance r is given by:
kQ1Q2/r
kQ1Q2*r
kQ1Q2/r^2
kQ1Q2*r^2
Explanation - Electric potential energy: U = k * q1 * q2 / r.
Correct answer is: kQ1Q2/r
Q.14 If electric flux through a closed surface is zero, it implies:
No charge inside
No field inside
No field outside
Charges are on surface
Explanation - Gauss's law: Φ = Q_inside / ε0. Zero flux → zero net charge inside.
Correct answer is: No charge inside
Q.15 The electric field due to a point charge decreases with distance as:
1/r
1/r^2
1/r^3
r^2
Explanation - Coulomb's law: E = kQ/r^2.
Correct answer is: 1/r^2
Q.16 A small positive test charge is placed near a positive point charge. The force on the test charge is:
Attractive
Repulsive
Zero
Depends on mass
Explanation - Like charges repel; force acts along the line joining the charges, away from the source charge.
Correct answer is: Repulsive
Q.17 Potential difference between two points in a uniform electric field is:
E*d
E/d
E*d^2
E/d^2
Explanation - V = E*d, where d is the distance along the direction of the field.
Correct answer is: E*d
Q.18 The work done in moving a charge in an electric field depends on:
Path taken
Initial and final points
Charge mass
Time taken
Explanation - Electrostatic field is conservative; work depends only on initial and final positions.
Correct answer is: Initial and final points
Q.19 What is the field at the midpoint of a dipole along the axial line?
Maximum
Zero
Minimum
Half of max
Explanation - At the midpoint of a dipole, along the axis connecting the charges, the fields due to each charge cancel exactly.
Correct answer is: Zero
Q.20 Electric field lines start and end on:
Positive and negative charges
Neutral objects
Anywhere
Magnetic poles
Explanation - By definition, field lines originate on positive charges and terminate on negative charges.
Correct answer is: Positive and negative charges
Q.21 The number of electric field lines is proportional to:
Charge magnitude
Distance from charge
Potential
Energy
Explanation - Field line density is proportional to the magnitude of the source charge.
Correct answer is: Charge magnitude
Q.22 A uniformly charged thin spherical shell produces electric field outside as if:
Point charge at center
Uniform inside shell
Zero everywhere
Field outside varies with shape
Explanation - By Gauss’s law, outside a spherical shell, field is same as if total charge is concentrated at center.
Correct answer is: Point charge at center
Q.23 If a positive charge is released in an electric field, it moves:
Along field lines
Opposite to field lines
Perpendicular
Randomly
Explanation - Positive charges move in direction of electric field; negative charges move opposite.
Correct answer is: Along field lines
Q.24 The potential at the surface of a charged conductor is:
Same everywhere
Zero
Maximum at corners
Depends on shape
Explanation - A conductor in electrostatic equilibrium has constant potential over its surface.
Correct answer is: Same everywhere
Q.25 If a test charge is negative, the force direction in an electric field is:
Along field lines
Opposite to field lines
Perpendicular
Zero
Explanation - Negative charges experience force opposite to the direction of electric field.
Correct answer is: Opposite to field lines