Verified Solution • 2025–26 Session moderate

QPages 165-170: Q7: HC Verma: Concepts of Physics - Volume 2 Capacitors Pages 165-170: Q7 Solution: Three capacitors having capacitances 20 �F, 30 �F and 40 �F are …

⚠️ Common Exam Traps & Conceptual Pitfalls

Students frequently calculate the battery work as $W=qV$ for a capacitor bank, forgetting that the stored energy (and thus the work done in an ideal circuit) is $W=\frac12 C_{eq}V^2$. Using $qV$ doubles the correct value and also leads to unit errors when the capacitances are given in µF.

Three capacitors having capacitances 20 �F, 30 �F and 40 �F are connected in series with a 12 V battery. Find the charge on each of the capacitors. How much work has been done by the battery in charging the capacitors?

Step-by-Step Verified Solution

**Answer:** Charge on each = 110 _C, Work done = 1.33×10−31.33 \times 10^{-3} J. **Step-by-Step Explanation:** In series, the equivalent capacitance is:
\frac{1}{C_{eq}} = \frac{1}{20} + \frac{1}{30} + \frac{1}{40} \Rightarrow C_{eq} = 9.23 \text{ _F}
Charge on each capacitor is the same: q=CeqV=9.23×12=110q = C_{eq}V = 9.23 \times 12 = 110 _C. Work done by battery: W=qV=110×10−6×12=1.33×10−3W = qV = 110 \times 10^{-6} \times 12 = 1.33 \times 10^{-3} J .

All Questions in this Chapter

QPage 163: Q1 QPage 163: Q2 QPage 163: Q3 QPage 163: Q4 QPage 163: Q5 QPage 163: Q6 QPage 163: Q7 QPage 164: Q1 QPage 164: Q2 QPage 164: Q3 QPage 164: Q4 QPage 164: Q5 QPage 164: Q6 QPage 164: Q7 QPage 164: Q8 QPage 164: Q9 QPage 164: Q10 QPage 164: Q11 QPage 164: Q12 QPages 164-165: Q1 QPages 164-165: Q2 QPages 164-165: Q3 QPages 164-165: Q4 QPages 164-165: Q5 QPages 164-165: Q6 QPages 164-165: Q7 QPages 165-170: Q1 QPages 165-170: Q2 QPages 165-170: Q3 QPages 165-170: Q4 QPages 165-170: Q5 QPages 165-170: Q6 QPages 165-170: Q7 QPages 165-170: Q8 QPages 165-170: Q9 QPages 165-170: Q10 QPages 165-170: Q11 QPages 165-170: Q12 QPages 165-170: Q13 QPages 165-170: Q14 QPages 165-170: Q15 QPages 165-170: Q16 QPages 165-170: Q17 QPages 165-170: Q18 QPages 165-170: Q19 QPages 165-170: Q20 QPages 165-170: Q21 QPages 165-170: Q22 QPages 165-170: Q23 QPages 165-170: Q24 QPages 165-170: Q25 QPages 165-170: Q26 QPages 165-170: Q27 QPages 165-170: Q28 QPages 165-170: Q29 QPages 165-170: Q30 QPages 165-170: Q31 QPages 165-170: Q32 QPages 165-170: Q33 QPages 165-170: Q34 QPages 165-170: Q35 QPages 165-170: Q36 QPages 165-170: Q37 QPages 165-170: Q38 QPages 165-170: Q39 QPages 165-170: Q40 QPages 165-170: Q41 QPages 165-170: Q42 QPages 165-170: Q43 QPages 165-170: Q44 QPages 165-170: Q45 QPages 165-170: Q46 QPages 165-170: Q47 QPages 165-170: Q48 QPages 165-170: Q49 QPages 165-170: Q50 QPages 165-170: Q51 QPages 165-170: Q52 QPages 165-170: Q53 QPages 165-170: Q54 QPages 165-170: Q55 QPages 165-170: Q56 QPages 165-170: Q57 QPages 165-170: Q58 QPages 165-170: Q59 QPages 165-170: Q60 QPages 165-170: Q61 QPages 165-170: Q62 QPages 165-170: Q63 QPages 165-170: Q64 QPages 165-170: Q65 QPages 165-170: Q66 QPages 165-170: Q67 QPages 165-170: Q68

Related Learning Resources & Exam Preparation

Chapter Practice Bank
Practice all topic-wise questions from Capacitors
Reference Textbook Solutions
Explore complete chapter exercises for HC Verma: Concepts of Physics - Volume 2
Competitive PYQ Question Bank
Browse year-wise authentic previous years' questions with solutions
Authentic CBT Mock Tests
Simulate official exam environment with live timer and percentile scoring