# Homework Help: 3 part hypothetical battery question

1. Jan 12, 2010

### almedmat

1. The problem statement, all variables and given/known data
A 3.50 µF capacitor is charged by a 13.0 V battery. It is disconnected from the battery and then connected to an uncharged 4.44 µF capacitor (Fig. 17-29).

Figure 17-29
Determine the total stored energy at the following points in time.

(a) before the two capacitors are connected
____ J
(b) after they are connected
____ J
(c) What is the change in energy?
____ J

2. Relevant equations

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3. The attempt at a solution
No idea

2. Jan 12, 2010

### rl.bhat

Didn't you find any relevant equation about the capacitor in your text book?
For example, the relation between capacitor, charge stored in the capacitor and voltage across the plates of the capacitor. What is the expression for the energy stored in the capacitor?

3. Jan 12, 2010

### ideasrule

After the capacitors are connected, the charges on the two capacitors must sum to the initial charge on C1. The voltage across the two capacitors must be equal. Write out equations representing these two facts, and solve for the voltage. Then remember that E=(1/2)CV^2.