(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A 1.00 micro-F capacitor charged to 50.0 V and a 2.00 micro-F capacitor charged to 20.0 V are connected, with the positive plate of each connected to the negative plate of the other. What is the final charge on the 1.00 micro-F capacitor?

2. Relevant equations

Q = CV

3. The attempt at a solution

Let a subscript of 1 denote the 1.00 micro-F capacitor, and a subscript of 2 denote the other.

Intially:

Q1 = C1V1 = 50 micro-C

Q2 = C2V2 = 40 micro-C

When the two capacitors are connected together, the first one has charge Q1' and the second has charge Q2' with:

Q1' + Q2' = 50 - 40 = 10 micro-C

The total potential drop around the loop must be zero, so we have

V1' = V2'

so

Q1'/C1 = Q2'/C2

Then when I solve for Q1', I get 3.3 micro-C, which is wrong. The correct answer according to the textbook is 45 micro-C.

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# Homework Help: Two capacitors

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