Electrostatic Potential and Capacitance — Class 12 MCQs with Answers
Class 12 CBSE Physics · Chapter 2
90 practice questions · 30 Easy · 30 Medium · 30 Hard · Updated
Practise the most important Class 12 CBSE Physics questions from Chapter 2, "Electrostatic Potential and Capacitance". You get 9 timed quizzes made from 90 NCERT-based MCQs, with answers and explanations. The questions are split into 30 Easy, 30 Medium and 30 Hard. Warm up on the basics, then move on to the exam-level questions that set top scorers in CBSE & Maharashtra HSC Board exams, JEE Main, MHT-CET, JEE Advanced and NEET UG apart.
To score well in "Electrostatic Potential and Capacitance", focus on numericals, derivations and applying concepts. Each MCQ here is timed and uses exam-style marking (+4 correct, −1 wrong, 0 skipped). This trains you to stay accurate under time pressure, as real papers need. Every question has a short explanation, so a wrong answer becomes a quick lesson. It is the fastest way to fix gaps before a test.
Use this chapter for focused revision. Start with the Easy set to check your basics on Electrostatic Potential and Capacitance, then move to Medium and Hard to practise applying them. Your accuracy, streaks and XP save automatically. This chapter also adds to your overall Class 12 Physics mastery score. 14 sample questions are solved in full below, with the answer and a worked explanation. Sign in free to start practising.
Key concepts: Electrostatic Potential and Capacitance (Class 12 Physics)
Energy in electrostatics: potential and potential energy, how the field is the negative gradient of potential, equipotential surfaces, conductors and electrostatic shielding, dielectrics and polarisation, capacitance and the parallel plate capacitor, series and parallel combinations, and the energy stored in a charged capacitor.
- Electrostatic potential energy
- The work done by an external agent in assembling a configuration of charges from infinite separation, brought together without acceleration.
- Electric potential
- The potential energy per unit charge at a point, measured in volts. It is a SCALAR, which makes it far easier to work with than the field.
- Potential of a point charge
- Varies as q/r and, unlike the field, carries the sign of the charge — so the potential near a negative charge is genuinely negative.
- Relation between E and V
- The field is the negative gradient of potential, E = −dV/dr. Field points from high to low potential, in the direction of steepest fall.
Electrostatic Potential and Capacitance — important questions & MCQs with answers (Class 12 Physics)
14 solved questions from this chapter's difficulty levels, each with its answer and explanation. The other 76 are timed and scored when you sign in.
- Q1Easy
SI unit of electric potential:
A.WattB.NewtonC.Volt (J/C)✓ CorrectD.TeslaAnswer: C. Volt (J/C)
Explanation: Potential is defined as work done per unit charge, V = W/q, so its SI unit is joule per coulomb — the volt. Watt and tesla measure power and magnetic field, not potential.
- Q2Easy
SI unit of capacitance:
A.VoltB.Farad✓ CorrectC.OhmD.CoulombAnswer: B. Farad
Explanation: Capacitance C = Q/V, charge per unit potential, so its SI unit is coulomb per volt — the farad. Ohm measures resistance and volt measures potential, not charge storage.
- Q3Easy
Potential at distance r from point charge q:
A.kq/r✓ CorrectB.kq/r²C.kq²/rD.kqrAnswer: A. kq/r
Explanation: Potential of a point charge follows V = kq/r, falling off as 1/r — not 1/r² like the field E, which is the easy mix-up here.
- Q4Easy
Capacitance is defined as:
A.Q²VB.V/QC.QVD.Q/V✓ CorrectAnswer: D. Q/V
Explanation: Capacitance is defined as charge stored per unit potential difference, C = Q/V — not V/Q, which would make farads shrink as stored charge grows.
- Q5Easy
Electric potential is a:
A.VectorB.PseudovectorC.TensorD.Scalar✓ CorrectAnswer: D. Scalar
Explanation: Potential has only magnitude, no direction, so it adds algebraically as V = Σkqᵢ/rᵢ — unlike the field E, which is a vector needing components.
- Q6Easy
Inserting a dielectric of constant K between plates of a capacitor:
A.Decreases CB.No effectC.Increases C by K✓ CorrectD.Makes C zeroAnswer: C. Increases C by K
Explanation: A dielectric of constant K reduces the field between the plates for the same charge, so V drops and capacitance rises by exactly that factor: C → KC.
- Q7Medium
Potential energy of charge q at potential V:
A.qV✓ CorrectB.q/VC.q²VD.V/qAnswer: A. qV
Explanation: Since potential V is work done per unit charge, the potential energy of a charge q sitting at that point is simply U = qV — not q/V, which would have the wrong units.
- Q8Medium
Capacitance of parallel plate (vacuum):
A.ε₀d/AB.d/(ε₀A)C.ε₀A/d✓ CorrectD.A/(ε₀d)Answer: C. ε₀A/d
Explanation: For a vacuum parallel-plate capacitor, C = ε₀A/d — capacitance rises with more overlap area A and falls with wider separation d; flipping either ratio is the usual slip.
- Q9Medium
PE of two point charges q₁, q₂ at distance r:
A.kq₁q₂/r²B.kq₁q₂/r✓ CorrectC.kq₁q₂rD.k(q₁+q₂)/rAnswer: B. kq₁q₂/r
Explanation: Electrostatic potential energy of two point charges equals the work to bring them from infinity to separation r: U = kq₁q₂/r — 1/r, not 1/r² like the force.
- Q10Medium
Parallel-plate capacitor C is fully filled with dielectric K. New capacitance:
A.C/KB.K²CC.CD.KC✓ CorrectAnswer: D. KC
Explanation: Filling the entire gap with a dielectric of constant K weakens the field for the same charge, so potential drops and capacitance rises by that same factor: C' = KC.
- Q11Medium
Potential at 30 cm from a 5 nC charge:
A.1500 VB.15 VC.150 V✓ CorrectD.50 VAnswer: C. 150 V
Explanation: Using V = kq/r: V = (9×10⁹ × 5×10⁻⁹)/0.3 = 45/0.3 = 150 V — forgetting to convert 30 cm to 0.3 m is the usual slip that gives 1500 V instead.
- Q12Hard
Three charges +q at vertices of equilateral triangle of side a. Total PE of system:
A.3kq²/a✓ CorrectB.kq²/aC.6kq²/aD.kq²/(3a)Answer: A. 3kq²/a
Explanation: Total potential energy sums every unique pair: three pairs each separated by a, all contributing kq²/a, giving 3kq²/a — not 6kq²/a, which would double-count each pair.
- Q13Hard
Energy stored in capacitor:
A.CV²B.CVC.½CV²✓ CorrectD.½C²VAnswer: C. ½CV²
Explanation: Energy stored in a charged capacitor is U = ½CV² = ½QV = Q²/(2C) — the factor of ½ comes from integrating V dQ as charge builds up gradually, not instantly.
- Q14Hard
Two concentric shells: inner Q₁ (radius a), outer Q₂ (radius b > a). Potential of inner shell:
A.k(Q₁+Q₂)/bB.kQ₁/aC.kQ₂/bD.k(Q₁/a + Q₂/b)✓ CorrectAnswer: D. k(Q₁/a + Q₂/b)
Explanation: Potential adds from every source: the inner shell's own charge gives kQ₁/a at its surface, plus the outer shell contributes kQ₂/b there since points inside a shell see its surface value: V = kQ₁/a + kQ₂/b.
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Start this chapter free →Electrostatic Potential and Capacitance — FAQs
What are the key concepts in Class 12 Physics Electrostatic Potential and Capacitance?+
Energy in electrostatics: potential and potential energy, how the field is the negative gradient of potential, equipotential surfaces, conductors and electrostatic shielding, dielectrics and polarisation, capacitance and the parallel plate capacitor, series and parallel combinations, and the energy stored in a charged capacitor. Key ideas include Electrostatic potential energy, Electric potential, Potential of a point charge, Relation between E and V.
What does Class 12 Physics Chapter 2 (Electrostatic Potential and Capacitance) cover on XamBaaz?+
It has 90 NCERT-based MCQs on "Electrostatic Potential and Capacitance": 30 Easy, 30 Medium and 30 Hard. Together they make 9 timed quizzes, and you never get the same set twice. Every question has an instant explanation. They help you prepare for CBSE & Maharashtra HSC Board exams, JEE Main, MHT-CET, JEE Advanced and NEET UG.
Are these "Electrostatic Potential and Capacitance" questions free to practise?+
Yes. Sign in with Google to practise "Electrostatic Potential and Capacitance" free. Full unlimited access is ₹999/year on a launch offer until 1 December 2026. No chapter is charged separately.
How should I revise "Electrostatic Potential and Capacitance" for the exam?+
Start with the Easy quiz to check your basics, then try Medium and Hard to practise applying them. There are 9 timed quizzes on this chapter, so you can come back for a fresh set instead of one you have seen. Read each explanation, retry the questions you miss, and track your accuracy until it stays high.
Are these "Electrostatic Potential and Capacitance" MCQs available with answers?+
Yes. 14 sample questions are shown here in full, each with the correct option and a step-by-step "Why" explanation. Sign in free with Google to start practising, with instant scoring.
Is there negative marking in the "Electrostatic Potential and Capacitance" quizzes?+
Yes. The timed quizzes use exam-style marking: +4 for a right answer, −1 for a wrong one and 0 for a skip, the same negative marking as JEE Main, JEE Advanced and NEET UG. MHT-CET and CBSE board papers have no negative marking. Our mocks for those are scored their way.
What are the important questions from Electrostatic Potential and Capacitance (Class 12 Physics)?+
The questions that matter most test Electrostatic potential energy, Electric potential, Potential of a point charge, Relation between E and V. This page shows 14 solved important MCQs with answers and explanations; all 90 questions on the chapter are available as timed quizzes once you sign in.
Is there an online quiz for Electrostatic Potential and Capacitance?+
Yes — Class 12 Physics Electrostatic Potential and Capacitance has timed online quizzes at Easy, Medium and Hard levels, with instant scoring and a worked explanation on every question. The first quiz on the chapter is free.