Electrostatic Potential & Capacitance: Class 12 Previous Year Questions

Electrostatic Potential & Capacitance questions asked in CBSE board exams

Repeated questions first. Open the free app to see each question as it appeared in the paper, with its marking scheme.

1.  32. (a) Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates. 5 (b) Two air-filled capacitors of capacitances C1 and C2 are connected in parallel with a dc battery. …
   Board 20265 markslong answer
2.  23. A parallel plate capacitor of capacitance C has a dielectric slab between its plates. It is charged to a potential difference V by connecting it across a battery. The battery is then disconnected. If the dielectric slab is now withdrawn from the capacito…
   Board 20263 marksshort answer
3. In a series LCR circuit, the voltage across the resistor, capacitor and inductor is 10 V each. If the capacitor is short circuited, the voltage across the inductor will be 1 (A) 10 V (B) 5 2 V (C) 5 2 V (D) 10 2 V
   Board 20261 markMCQ
4.  23. (a) An electric field E = E0  i exists in a region of space. Draw three equipotential surfaces in the region. 3 (b) Two point charges –q and +q are located at points (–a, 0, 0) and (a, 0, 0) respectively. Find the electrostatic potential at point (x, 0,…
   Board 20263 marksshort answer
5. SECTION – A 1. Three point charges 2q, –2q and q are kept at the vertices of an equilateral triangle of side l. The potential energy of the system is 1 (A) zero (B) –2q2 0l (C) q2 20l (D) – q2 0l
   Board 20261 markMCQ
6.  21. Draw the plot of potential energy of a pair of nucleons as a function of their separation. Write two important conclusions that can be drawn from this plot. 2 { } 14   –  22. (a)               …
   Board 20262 marksshort answer
7.  9. The figure shows the variation of capacitive reactance (XC) of two ideal capacitors of capacitances C1 & C2 with the reciprocal of angular frequency (1/) of ac source. The value of C1/C2 is 1 (A) 1 2 (B) 2 (C) 3 (D) 1 3 { } 8  10.     …
   Board 20261 markMCQ
8. (a) (i) Two point charges 5 ·C and -1l ·C are placed at points (-3 cm, O, 0) and (3 cm, 0, 0) respectively. An external electric field Calculate the change in electrostatic energy of the system due to the electric field. (ii) A system of two conductors is plac…
   Board 20255 markslong answer
9. (a) Two wires of the same material and the same radius have their lengths in the ratio 2 : 3. They are connected in parallel to a battery which supplies a current of 15 A. Find the current through the wires. OR (b) In the circuit three ideal cells of e.m.f. V,…
   Board 20252 marksshort answer
10. g p g p q 29. A parallel plate capacitor has two parallel plates which are separated by an insulating medium like air, mica, etc. When the plates are connected to the terminals of a battery, they get equal and opposite charges and an electric field is set up i…
    Board 20254 marksshort answer
11. (a) A parallel plate capacitor is charged by an ac source. Show that the sum of conduction current (I) and the displacement current (I) has the same value at all points of the circuit. (b) In case (a) above, is Kirchhoff's first rule (junction rule) valid at e…
    Board 20253 marksshort answer
12. Ten capacitors, each of capacitance 1 µF, are connected in parallel to a source of 100 V. The total energy stored in the system is equal to : (A) 10 2 J (B) 10 3 J (C) 0·5 10 3 J (D) 5·0 10 2 J
    Board 20241 markMCQ
13. The reactance of a capacitor of capacitance C connected to an ac source of frequency nce of the capacitor is doubled and the frequency of the source is tripled, the reactance will become : (A) 6 X (B) 6X (C) X 3 2 (D) X 2
    Board 20241 markMCQ
14. Define the term - Distance of closest approach. How will it be affected, for an · - particle, if kinetic energy of the particle is doubled ?
    Board 20221 markvery short
15. The kinetic energy of an electron in ground state of hydrogen atom is 13.6 eV. What will be the potential energy of electron in this state? (a) -27.2 eV (b) +27.2 (c) -13.6 eV (d) 0 eV For Questions 13 to 16, two statements are given –one labelled Assertion (A…
    CBSE practice 2023-241 markAssertion-Reason
16. (a) A camera usually operates at 1.5 V and this potential difference is not sufficient to emit light energy using flash. For this purpose, the flash circuit of the camera has a capacitor that is charged to 300 V-330 V using various electrical components. If th…
    CBSE practice 2023-245 markslong answer
17. Two parallel plate capacitors X and Y have the same area of plates and same separation between plates, X has air and Y has dielectric of constant 2, between its plates. They are connected in series to a battery of 12V. The ratio of electrostatic energy stored …
    CBSE practice 2023-241 markMCQ
18. The capacitance of a capacitor is Co. It is connected to a battery of voltage V which charges the capacitor. With the capacitor still connected to the battery, a slab of dielectric material is introduced between the plates of the capacitor. 1 Which of the foll…
    CBSE practice 2022-231 markMCQ
19. When an electron in an atom moves from the ground state to a higher energy level what happens to its kinetic and potential energies? kinetic energy potential energy A increases Increases B increases Decreases C decreases Increases D decreases Decreases
    CBSE practice 2023-241 markvery short

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