Section A: Multiple Choice Questions (1 × 14 = 14 marks)
1. The unit of electric field is: a) V b) C c) N/C d) J
2. Electric field at the centre of a uniformly charged ring is: a) Maximum b) Zero c)
Infinite d) None of these
3. A point charge is placed inside a closed conducting surface. The net electric flux
depends on: a) Shape of surface b) Size of surface c) Charge enclosed d) Charge
outside the surface
4. The electric potential energy of a system of two positive charges is: a) Negative b)
Positive c) Zero d) Infinity
5. Electric field due to an infinite plane sheet of charge is: a) Directly proportional to
distance b) Inversely proportional to distance c) Independent of distance d) Zero
6. SI unit of capacitance is: a) C b) F c) V d) CV
7. Two charges are placed at a distance d. If one charge is doubled, the force becomes:
a) Doubled b) Halved c) Quadrupled d) Tripled
8. Electric field lines always begin and end on: a) Conductors b) Charges c) Neutral
points d) Dipoles
9. The net flux through a cube enclosing a charge q is: a) q/4πε b) q/ε c) q/2ε d) 0
10. If a conductor carries a net charge, the charge resides: a) Uniformly throughout b)
Inside the conductor c) On the surface d) Nowhere
11-12. Assertion (A) and Reason (R):
11. A: Electric field is conservative. R: Work done in a closed path in an electric field is
zero. a) A and R both correct, R explains A b) A correct, R incorrect c) A incorrect, R
correct d) Both incorrect
12. A: Capacitance increases if dielectric is inserted between capacitor plates. R:
Dielectric increases electric field between plates. (Options same as above)
13-14. Case-based MCQs:
Read the case: A spherical conductor of radius R is given a charge Q. The potential on the
surface is V.
13. What is the electric field just outside the surface? a) Q/εR b) Q/4πεR^2 c) Zero d)
None
14. What is the potential at a point distance 2R from center? a) V b) V/2 c) Q/8πεR d)
Q/8πε(2R)
Section B: Very Short Answer Type (2 × 7 = 14 marks)
15. Define electric flux. Write its SI unit.
16. What is the potential at a point on the equatorial line of an electric dipole?
17. State the principle of a parallel plate capacitor.
18. Why is the electric field inside a conductor zero in electrostatics?
19. A point charge is placed near a grounded conducting sphere. What happens to the
field lines?
20. What is the role of earthing in an electric setup?
21. Two capacitors of 2 μF and 3 μF are connected in series. Find the equivalent
capacitance.
Section C: Short Answer Type (3 × 9 = 27 marks)
22. Derive the expression for the electric field due to a dipole on its axial line.
23. Using Gauss's Law, derive the electric field due to a uniformly charged spherical shell
(outside point).
24. Derive the relation between electric field and electric potential.
25. A parallel plate capacitor is connected to a battery. If the plates are pulled apart, what
happens to: a) Capacitance b) Potential difference c) Energy stored
26. Derive the formula for the capacitance of a parallel plate capacitor with dielectric
constant K.
27. Calculate the work required to move a 5 μC charge through a potential difference of
12 V.
28. A charged conductor is connected to another identical uncharged conductor. What is
the final potential?
29. A metallic sphere of radius 10 cm is charged with 20 μC. Find the potential on the
surface. (ε = 8.85 x 10^-12)
30. Explain the concept of electric shielding with an example.
Section D: Long Answer Type (5 × 3 = 15 marks)
31. a) State and prove Gauss’s law in electrostatics.
b) Apply it to find the electric field due to an infinitely long straight charged wire.
32. A parallel plate capacitor with plate area A and separation d is connected to a battery
V. A dielectric of dielectric constant K is inserted completely. Derive expressions for:
a) Capacitance b) Electric field c) Energy stored
33. Case Study: A point charge q is placed at a distance d from an infinite grounded
conducting plane.
a) Use the method of images to find the field configuration.
b) Find the force on the charge.
c) How will the potential at a point between the charge and the plane vary?
