Series: 1/C_eq = 1/C₁ + 1/C₂ + ... (smaller than smallest). Parallel: C_eq = C₁ + C₂ + ... (sum). Same charge in series; same voltage in parallel.
-- NCERT Class 12 Physics, Ch. 2, p. 72Capacitors Series Parallel
8 MCQs1 revision card9-step worked example
Source: NCERT ElectrostaticsOfficial key: NTA-verifiedLast updated: 21 Sep 2026
Capacitors Series Parallel, explained for NEET
The trap: carrying the resistor rules over to capacitors. For capacitors the rules are the other way round: in series the reciprocals add, in parallel the capacitances add. A common confusion is to add capacitances in series (or add reciprocals in parallel) out of resistor habit.
Series (NCERT Class 12 Physics Part I, Chapter 2, Section 2.14.1, pages 71–72). The charges on the two plates, ±Q, are the same on each capacitor; NCERT explains that otherwise charge would flow along the connecting wire until the net charge on each capacitor is zero. The potential drops add, V = V₁ + V₂ + … + Vₙ, which gives
1/C = 1/C₁ + 1/C₂ + … + 1/Cₙ (Eq. 2.60, page 72)
Parallel (Section 2.14.2, page 72). The same potential difference V is applied across every capacitor, but the charges Q₁ = C₁V, Q₂ = C₂V are not necessarily the same. The charges add, Q = Q₁ + Q₂, which gives C = C₁ + C₂ (Eq. 2.64, page 72) and, for n capacitors,
C = C₁ + C₂ + … + Cₙ (Eq. 2.67, page 72)
Memory hook. Capacitors in series follow the form of resistors in parallel; capacitors in parallel follow the form of resistors in series.
Bridge to NEET. Combination questions usually take two steps: reduce the network to one equivalent capacitance, then find charge or voltage. Use "same Q" for a series chain and "same V" for a parallel group. In series, the smaller capacitance takes the larger share of the voltage, because V = Q/C with Q common. NCERT Example 2.9 (page 73) is the model: reduce a series chain first, then add it in parallel with the remaining capacitor.
Watch out: after adding reciprocals in series, invert the sum. 1/3 + 1/6 = 0.50 is 1/C, not C; C = 2.0.
Can you answer these Capacitors Series Parallel MCQs?
Select an option to see the explanation. Wrong answers show why your choice was tempting — and name the exact trap it exploits.
MCQ 1Easy RecallPractice
For capacitors connected in series to a battery, which quantity is the same for every capacitor in the chain?
Show answer and why every option is right or wrong
Answer: B. NCERT Class 12 Physics Part I, Chapter 2, Section 2.14.1 (page 71): in the series combination the charges on the two plates (±Q) are the same on each capacitor; the potential drops across them add.
Why A is wrong: A is wrong because equal potential difference is the parallel-combination property; in series the individual potential drops add up to the total V.
Why C is wrong: C is wrong because capacitors in series can have any capacitances; the combination rule places no condition that they be equal.
Why D is wrong: D is wrong because sharing charge in proportion to capacitance (Q = CV with common V) describes a parallel group, not a series chain.
MCQ 2Easy RecallPractice
According to NCERT, the effective capacitance C of n capacitors C₁, C₂, …, Cₙ connected in parallel is given by:
Show answer and why every option is right or wrong
Answer: D. NCERT Class 12 Physics Part I, Chapter 2, Eq. 2.67 (page 72): for a parallel combination the charges add at a common V, so C = C₁ + C₂ + … + Cₙ.
Why A is wrong: A is wrong because adding reciprocals is the series rule (Eq. 2.60); using it here is the series-parallel formula swap.
Why B is wrong: B is wrong because the capacitances add in full; dividing the sum by n gives an average, which is not the effective capacitance.
Why C is wrong: C is wrong because it mixes the two rules: the sum of capacitances is C itself in parallel, not 1/C.
MCQ 3Easy RecallPractice
The rule for combining capacitors in series has the same mathematical form as the rule for combining:
Show answer and why every option is right or wrong
Answer: A. Capacitors in series add as reciprocals, 1/C = Σ1/Cᵢ (NCERT Chapter 2, Eq. 2.60, page 72), which is the form of resistors in parallel. The capacitor rules are the opposite of the resistor rules.
Why B is wrong: B is wrong because resistors in series add directly, which is the form of capacitors in parallel; this is the resistor-habit swap.
Why C is wrong: C is wrong because capacitors in parallel add directly (C = ΣCᵢ), not as reciprocals.
Why D is wrong: D is wrong because charges in a parallel group add directly, Q = Q₁ + Q₂ (NCERT Eq. 2.62); that is a direct sum, not a reciprocal sum.
MCQ 4Direct ApplicationPYQ Pattern
Capacitors of 3.0 µF and 6.0 µF are connected in series. Their equivalent capacitance is:
Show answer and why every option is right or wrong
Answer: D. 1/C = 1/3.0 + 1/6.0 = 0.50 µF⁻¹, so C = 2.0 µF (NCERT Chapter 2, Eq. 2.60, page 72). A series combination is smaller than the smallest capacitor.
Why A is wrong: A is wrong because 9.0 µF = 3.0 + 6.0 uses the parallel rule for a series combination (the formula swap).
Why B is wrong: B is wrong because 0.50 is the sum 1/3.0 + 1/6.0, which is 1/C; the sum was not inverted.
Why C is wrong: C is wrong because 4.5 µF is the average (3.0 + 6.0)/2, which is neither combination rule.
MCQ 5Direct ApplicationPYQ Pattern
Capacitors of 2.0 µF, 5.0 µF and 8.0 µF are connected in parallel. The equivalent capacitance is:
Show answer and why every option is right or wrong
Answer: B. In parallel the capacitances add: C = 2.0 + 5.0 + 8.0 = 15 µF (NCERT Chapter 2, Eq. 2.67, page 72).
Why A is wrong: A is wrong because 1.2 µF = 1/(1/2.0 + 1/5.0 + 1/8.0) = 1/0.825 uses the series rule for a parallel group (the formula swap).
Why C is wrong: C is wrong because 0.83 is the reciprocal sum 1/2.0 + 1/5.0 + 1/8.0 = 0.825 left uninverted, and it applies the series rule to a parallel group as well.
Why D is wrong: D is wrong because 5.0 µF is the average 15/3; the parallel capacitances add in full, they are not averaged.
MCQ 6Direct ApplicationPYQ Pattern
Capacitors of 4.0 µF and 12 µF are connected in parallel across a 6.0 V source. The charge on the 12 µF capacitor is:
Show answer and why every option is right or wrong
Answer: A. In parallel each capacitor has the full 6.0 V across it (NCERT Chapter 2, Section 2.14.2, Eq. 2.61, page 72), so Q = CV = 12 µF × 6.0 V = 72 µC.
Why B is wrong: B is wrong because 24 µC = 4.0 µF × 6.0 V is the charge on the other capacitor.
Why C is wrong: C is wrong because 18 µC = 3.0 µF × 6.0 V uses the series equivalent (4.0 × 12)/(4.0 + 12) = 3.0 µF and assumes a common charge, treating the parallel group as a series chain.
Why D is wrong: D is wrong because 96 µC = (4.0 + 12) µF × 6.0 V is the total charge drawn by the parallel group, not the charge on the 12 µF capacitor alone.
MCQ 7CalculationPYQ Pattern
Capacitors of 6.0 µF and 3.0 µF are connected in series across a 12 V source. The potential difference across the 3.0 µF capacitor is:
Show answer and why every option is right or wrong
Answer: C. 1/C = 1/6.0 + 1/3.0 = 0.50 µF⁻¹, so C = 2.0 µF; Q = CV = 2.0 µF × 12 V = 24 µC, the same on both capacitors in series (NCERT Chapter 2, pages 71–72). V across 3.0 µF = Q/C = 24 µC / 3.0 µF = 8.0 V.
Why A is wrong: A is wrong because 4.0 V = 24 µC / 6.0 µF is the voltage across the 6.0 µF capacitor; with a common Q, the smaller capacitance takes the larger voltage.
Why B is wrong: B is wrong because it treats the capacitors as a parallel group with the full 12 V across each; in series the two drops must add to 12 V.
Why D is wrong: D is wrong because 6.0 V splits 12 V equally, which holds only for equal capacitances in series.
MCQ 8CalculationPYQ Pattern
Capacitors of 2.0 µF and 4.0 µF are connected in parallel, and this pair is connected in series with a 3.0 µF capacitor. The equivalent capacitance of the network is:
Show answer and why every option is right or wrong
Answer: C. Parallel pair: 2.0 + 4.0 = 6.0 µF (Eq. 2.64). In series with 3.0 µF: 1/C = 1/6.0 + 1/3.0 = 0.50 µF⁻¹, so C = 2.0 µF (Eq. 2.60). NCERT Chapter 2, page 72.
Why A is wrong: A is wrong because 4.3 µF comes from swapping both rules: 2.0 and 4.0 in series give 1.33 µF, then adding 3.0 µF in parallel gives 4.33 µF.
Why B is wrong: B is wrong because 9.0 µF = 2.0 + 4.0 + 3.0 treats all three capacitors as parallel, ignoring the series link.
Why D is wrong: D is wrong because 0.92 µF = 1/(1/2.0 + 1/4.0 + 1/3.0) treats all three capacitors as series, ignoring the parallel pair.
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Capacitors Series Parallel: quick recall before you leave
How do you solve a Capacitors Series Parallel question? A worked example
- 1
Given
NCERT Class 12 Physics Part I, Chapter 2, Example 2.9 (page 73). A network of four capacitors, each of capacitance 10 µF (1.0 × 10⁻⁵ F), is connected to a 500 V (5.00 × 10² V) supply. In the network (NCERT Fig. 2.29), C₁, C₂ and C₃ are connected in series, and this series chain is connected in parallel with C₄ across the supply.
- 2
Required
(a) The equivalent capacitance of the network. (b) The charge on each capacitor.
- 3
Concept
Reduce the series chain C₁–C₂–C₃ to one capacitor C′ (reciprocals add). C′ and C₄ are in parallel (capacitances add). For charges: C₁, C₂, C₃ carry the same charge Q, and the chain's potential drops add to 500 V; C₄ has the full 500 V across it.
- 4
Formula
Series: 1/C′ = 1/C₁ + 1/C₂ + 1/C₃ (Eq. 2.60, page 72)
Parallel: C = C′ + C₄ (Eq. 2.64, page 72)
Charges: Q/C₁ + Q/C₂ + Q/C₃ = 500 V, which gives Q = C′ × 500 V; and Q′/C₄ = 500 V - 5
Substitution
(a) 1/C′ = 1/10 + 1/10 + 1/10 (µF⁻¹); C = C′ + 10 µF
(b) Q = 500 V × (10/3) µF; Q′ = 500 V × 10 µF - 6
Calculation
(a) 1/C′ = 3/10 µF⁻¹, so C′ = (10/3) µF. C = (10/3 + 10) µF = 13.3 µF.
(b) Q = 500 × (10/3) × 10⁻⁶ C = 1.7 × 10⁻³ C on each of C₁, C₂ and C₃.
Q′ = 500 × 10 × 10⁻⁶ C = 5.0 × 10⁻³ C on C₄.
The count of three identical capacitors in the chain (the 3 in 10/3) is exact and does not contribute to the sig-fig count. The rounding shown (13.3 µF, 1.7 × 10⁻³ C, 5.0 × 10⁻³ C) follows NCERT's printed answers. - 7
Final answer
(a) C = 13.3 µF; (b) 1.7 × 10⁻³ C on each of C₁, C₂, C₃ and 5.0 × 10⁻³ C on C₄
- 8
Common trap
Adding all four capacitances (40 µF), or giving every capacitor the charge 10 µF × 500 V = 5.0 × 10⁻³ C. Only C₄ has the full 500 V across it. The series chain shares the 500 V: each of C₁, C₂, C₃ has Q/C₁ = (500/3) V ≈ 167 V, and three such drops add back to 500 V.
- 9
Similar NEET-style question
"Three capacitors of 4.0 µF each are connected so that two of them are in parallel and this pair is in series with the third. Find the equivalent capacitance."
Strategy: Parallel pair: 4.0 + 4.0 = 8.0 µF. In series with 4.0 µF: C = (8.0 × 4.0)/(8.0 + 4.0) = 2.7 µF. Adding all three (12 µF) or taking all three in series (1.3 µF) are the swap errors.
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What to remember before solving Capacitors Series Parallel questions
Which Capacitors Series Parallel formulas do you need for NEET?
1 formula — click to collapse
Capacitors series and parallel
Series: same Q on each, voltages add. Parallel: same V across each, charges add.
| Symbol | Quantity | SI Unit |
|---|---|---|
| C_eq | equivalent capacitance | F |
| C_i | individual | F |
Valid when
- Series: same charge through chain
- Parallel: same voltage across all
Where do students lose marks on Capacitors Series Parallel?
These are the exact patterns that cause wrong answers in NEET. Each trap includes when it triggers and how to avoid it.
2 items — click to collapse
Category: Similar Terms
Student uses series formula for parallel circuit (or vice versa). Series capacitors: 1/C reciprocals add; parallel: C add directly. Note: opposite of resistor rules.
When it triggers
Capacitor combination problem.
How to avoid
Capacitors in SERIES → reciprocals add (like resistors in parallel). Capacitors in PARALLEL → values add (like resistors in series). Counter-intuitive vs resistor rules — memorise carefully.
Root cause: formula misuse
Correction
OPPOSITE of resistor rules. Capacitors in series → reciprocals add (1/C_eq = Σ1/C_i). Capacitors in parallel → values add (C_eq = ΣC_i). Counter-intuitive vs resistors; memorise carefully.
More in Electrostatics: 1 exam trap or mistake · 10 formulas · 5 question patterns from its other lessons.
Capacitors Series Parallel questions from past NEET papers
No question in our NEET 2020–2025 set targets this topic directly.
How does NEET ask about Capacitors Series Parallel?
1 recurring pattern from past papers — click to collapse
Combination of capacitors. Series: 1/C = sum(1/C_i); parallel: C = sum(C_i).
Multi StepEasy
Common distractors
swaps series parallel formulas
Uses series formula for parallel circuit
Sources
Page numbers are the ones printed in the current NCERT textbook (2023 rationalised edition), unless marked pre-2023. The books are free at ncert.nic.in.
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