# Potential Related to Electric Field?

1. Jul 20, 2010

### mitchellhewer

A manufacturer claims that a carpet will not generate more than 4.9kV of static electricity. What magnitude of charge would have to be transferred between a carpet and a shoe for there to be a 4.9kV potential difference between the shoe and the carpet. Approximate the shoe and the carpet as large sheets of charge separated by a distance d = 1.0mm. Area is not given in the question. Could someone please explain how to do this question in detail? Thank you in advance.

2. Jul 20, 2010

### Antiphon

Q=CV. What's the capacitance of the shoe?

3. Jul 20, 2010

### mitchellhewer

There is no area of the shoe given. Apparently, someone has told me that I can solve it in terms of σ, the charge per unit area, not the total charge.

4. Jul 20, 2010

### mitchellhewer

And there is no capaicitance given either.

5. Jul 21, 2010

### AJ Bentley

Why 4.9kV - sounds oddly precise.

The only thing I can suggest is that you need to at least estimate the size of a shoe, then treat it as a simple parallel plate capacitor.
Then C = 8.854×10−12* A/d

Each plate area A - say .1 * .05 gives C= 4.4 x 10-11.

Sounds about right - 40 to 50pF

So Q = 4900 * 50pF = 25 x 10-8 Coulombs.

You want electrons with that?