Electrostatic Potential and Capacitance Class 12 Physics Chapter Test 2026-27
A 25-question self-assessment covering electric potential, dipole, potential energy, conductors, dielectrics, capacitance, capacitor combinations and energy stored in a capacitor.
How to Use This Chapter Test
- Total questions: 25
- Suggested time: 35–40 minutes
- Format: 15 MCQs + 5 numericals + 5 conceptual/application questions
- Suggested practice rule: Attempt the test before checking the answer key.
- Important: These are original practice questions designed around the CBSE 2026–27 syllabus. They are not claimed to be official CBSE questions or past-year questions.
Open Chapter 2 Formula Sheet & Quick Revision
Section A — MCQs
Questions 1–15: Choose the most appropriate option.
1. The electric potential at a point is best defined as:
2. The electric potential due to a point charge q at distance r in vacuum is:
3. Which statement about electric potential is correct?
4. Work done in moving a charge along an equipotential surface is:
5. The electric field at a point is related to the potential by:
6. For a short electric dipole, the potential at a far-away point is proportional to:
7. The potential energy of two point charges q1 and q2 separated by r is:
8. In electrostatic equilibrium, the electric field inside the conducting material of a conductor is:
9. The capacitance of a parallel-plate capacitor in vacuum is:
10. Three capacitors are connected in parallel. The equivalent capacitance is:
11. In a simple series combination of capacitors, which quantity is the same on each capacitor?
12. The energy stored in a capacitor can be written as:
13. A dielectric of dielectric constant K completely fills the space between the plates of an isolated capacitor. Which statement is correct?
14. A capacitor remains connected to an ideal battery while a dielectric completely fills the gap. Which quantity remains constant?
15. The energy of an electric dipole in a uniform electric field is minimum when the dipole moment is:
Section B — Numericals
Questions 16–20: Show your working. Use ε0 = 8.85 × 10−12 F m−1 and k = 9 × 109 N m2 C−2 where required.
16. A point charge of +2 μC is placed in vacuum. Find the electric potential at a point 0.30 m from the charge.
17. Two charges +4 μC and −2 μC are separated by 0.20 m. Find the electrostatic potential energy of the pair, taking zero potential energy at infinite separation.
18. A parallel-plate capacitor has plate area 2.0 × 10−2 m2 and plate separation 1.0 × 10−3 m. The space between the plates is vacuum. Calculate its capacitance.
19. A 6 μF capacitor is charged to 100 V. Calculate (a) its charge and (b) the energy stored in it.
20. Two capacitors of 3 μF and 6 μF are connected in series across a 12 V battery. Find (a) the equivalent capacitance and (b) the charge on each capacitor.
Section C — Conceptual & Application Questions
21. Explain why no work is done in moving a charge along an equipotential surface.
22. A point in space has zero electric potential. Can the electric field at that point still be non-zero? Explain with a suitable example or reasoning.
23. A charged capacitor is disconnected from its battery and then a dielectric slab completely fills the space between its plates. State what happens to its capacitance, charge, potential difference and stored energy. Give the reason for each change.
24. Two capacitors are connected in series. Explain why the charge magnitude on each capacitor is the same, while the potential differences across them need not be the same.
25. A student says: “If the electric potential at a point is zero, there can be no electric field at that point.” Is the statement correct? Explain carefully.
Answer Key — Check Only After Attempting
MCQs:
1-B, 2-C, 3-C, 4-C, 5-B, 6-B, 7-A, 8-A, 9-B, 10-C, 11-B, 12-C, 13-B, 14-C, 15-C
Numerical final answers:
16. 6.0 × 104 V
17. −0.36 J
18. 1.77 × 10−10 F ≈ 177 pF
19. (a) 6.0 × 10−4 C = 600 μC; (b) 0.03 J
20. (a) 2 μF; (b) 24 μC on each capacitor
Conceptual marking points:
21. Work W = qΔV. Along an equipotential surface ΔV = 0, therefore W = 0.
22. Yes. Electric potential and electric field are different quantities. For example, at the midpoint of two equal and opposite charges, the potential can be zero while the electric fields due to the two charges add rather than cancel.
23. For an isolated capacitor: C becomes KC; Q remains constant; V becomes V/K; U becomes U/K. The dielectric increases capacitance, while disconnection from the battery prevents charge from changing.
24. In a simple series connection, the same charge magnitude is established on each capacitor. Since V = Q/C, different capacitances can produce different potential differences.
25. No. V = 0 does not necessarily mean E = 0. Electric field depends on the spatial variation of potential, not merely its value at one point.
Worked Solutions — Numericals
16. Potential Due to a Point Charge
Given q = 2 × 10−6 C and r = 0.30 m.
V = kq/r
V = (9 × 109 × 2 × 10−6)/0.30
V = 6.0 × 104 V.
17. Potential Energy of Two Charges
Given q1 = +4 × 10−6 C, q2 = −2 × 10−6 C and r = 0.20 m.
U = kq1q2/r
U = (9 × 109 × 4 × 10−6 × −2 × 10−6)/0.20
U = −0.36 J.
The negative sign indicates a negative potential energy relative to the chosen zero at infinity.
18. Parallel-Plate Capacitance
C = ε0A/d
C = (8.85 × 10−12 × 2.0 × 10−2)/(1.0 × 10−3)
C = 1.77 × 10−10 F ≈ 177 pF.
19. Charge and Energy
Given C = 6 μF and V = 100 V.
Q = CV = 6 × 10−6 × 100
Q = 6.0 × 10−4 C = 600 μC.
U = ½CV2
U = ½ × 6 × 10−6 × 1002
U = 0.03 J.
20. Capacitors in Series
For two capacitors in series:
1/Ceq = 1/3 + 1/6 = 1/2
Ceq = 2 μF.
The charge in a simple series combination is the same on each capacitor:
Q = CeqV = 2 μF × 12 V
Q = 24 μC.
Self-Assessment
| Score | What to Do Next |
|---|---|
| 22–25 | Strong chapter-level preparation. Move to mixed practice and timed revision. |
| 18–21 | Good foundation. Revisit mistakes and practise the weaker question types. |
| 13–17 | Revise formulas and concepts, then retake the test after practice. |
| 0–12 | Return to the chapter notes and formula sheet before attempting the test again. |
Chapter 2 Preparation Path
All Chapter 2 resources
Concepts and explanations
Exam-oriented practice
Concept checks
Step-by-step practice
Application practice
Reasoning practice
Quick revision
Electric Charges and Fields
Syllabus & Source Note
This chapter test is aligned to the CBSE 2026–27 Physics curriculum for Chapter 2, which covers electric potential and potential difference; potential due to a point charge, dipole and system of charges; equipotential surfaces; electrostatic potential energy; conductors and insulators; free and bound charges; dielectrics and polarization; capacitors and capacitance; series and parallel combinations; parallel-plate capacitance with and without dielectric; and energy stored in a capacitor. CBSE specifies energy stored in a capacitor as formulae only, with no derivation in the listed syllabus scope. View the official CBSE Physics 2026–27 curriculum.
For the current Class XII 2026–27 sample question papers and marking schemes, use the official CBSE Academic page: CBSE Class XII 2026–27 SQP & MS.
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