CBSE Class 11-science Answered

With reference to NCERT TEXTBOOK FOR CLASS XII, I am posting my query as under,

In NCERT TEXTBOOK (PHYSICS) page no.88, question no.2.11, I am getting the required solution if I solve this numerical by finding the new capacitance considering the charged and uncharged capacitors to be connected in series. However, in another numerical, which is similar to question no.2.11 in page no.90, question no.2.25, I am getting the required result by using parallel method. If I solve it by considering the capacitors to be connected in series, it doesn't give the suggested result. Why is this so. How should I decide which method is to be used? It has not been mentioned in any of the two questions whether the second capacitor has been connected in series or parallel. Both the questions are framed in exactly similar manner. However, method used to find the anwer is different. The same thing was observed in the solution given in the "TEXTBOOK SOLUTIONS" feature of topperlearning.com. I request you to kindly tell me if I have made any mistake in interpretating these two questions.