# Charge flow in a RC circuit

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1. Jan 14, 2018 at 6:36 AM

### sumit_1

• Member advised to use the formatting template for all homework help requests; Thread moved to Introductory Physics Homework from Advanced Physics Homework.
I have a RC circuit which also includes a battery, the capacitor has some charge initially before we put all the components in the circuit. Now as I connect all of them then charge will start to flow, but wheather this charge will be the sum of initial charge on the capacitor and the new charge produced by the battery or it will be just the new charge produced by the battery?

According to me the charge flowing in the circuit should be the sum of the initial charge of the capacitor and the charge produced by the battery.
Is this correct?

2. Jan 14, 2018 at 7:23 AM

### scottdave

Look at how much charge (and polarity) will be on the capacitor after a long time. How does this compare with the charge and polarity before they're connected?

3. Jan 14, 2018 at 7:27 AM

### sumit_1

I connected the positive side of capacitor to the positive terminal of the battery.

4. Jan 14, 2018 at 7:32 AM

### scottdave

So can you calculate how much charge will be on the cap after a long time (if the cap was initially "empty")?

This ending number will be the same for a cap with some initial charge. But the amount supplied by the battery will be different.

5. Jan 14, 2018 at 7:34 AM

### scottdave

Do you know how much initial charge is on the capacitor?

6. Jan 14, 2018 at 7:38 AM

### sumit_1

I know the initial charge on the capacitor.

7. Jan 14, 2018 at 7:44 AM

### scottdave

Maybe think of it as adding money to your bank account. If you started with $10 and end with$50, how much money was added?

8. Jan 14, 2018 at 7:47 AM

### sumit_1

\$40 is added. But i want to know how much amount of charge will flow in the circuit as i have described in the problem?

9. Jan 14, 2018 at 7:50 AM

### scottdave

Do you have details of the setup that you can share, along with what you have worked out so far?