# Battery and potential difference

1. Feb 23, 2005

### thisisfudd

A battery fully charges a parallel plate air gap capacitor. The battery is removed and the plates are pulled apart. What happens to the potential difference between the plates as they are being separated?

So I guess resistance and I operate over a certain length. So the length is increasing, so that means resistance and length increase, so potential difference increases? Is this correct logic?

2. Feb 23, 2005

### faust9

What resistance? caps should have infinate resistance between the plates. There is an equation relating charge to the distance between the plates isn't there?

3. Feb 23, 2005

### mewmew

Well if the electric field stays the same and distance increases than electric potential would increase. A batterys job is simply to move electrons from one plate to another basically, so with no battery connected no electrons could be moved from each plate to make up for the change in distance and the potential would increase, correct?

4. Feb 23, 2005

### Claude Bile

The Potential would increase, as work is required to move the plates apart.

Claude.

5. Feb 24, 2005

### stunner5000pt

When you think capacitance you involve capactiance concepts when trhe question asks about the potential difference between the two plates!

i believe you have a formula for the voltage across two plates in a parallel plate capacitor whjich is related to the charge, distance and area of the two plates. Since you only change one thing d (distance between the plates) V will change accordingly