# Difference in the maximum potential capacitance

1. Jun 30, 2009

### Apprentice123

Determine (a) capacitance and (b) the difference in the maximum potential that can be applied to a parallel plate capacitor filled with Teflon (k=2,1), whose area the plate is 1,75 cm^2 and the separation between the plates is 40x10^{-6}m.

My solution

(a) C. = ( E. * A )/d = 3,87x10^{-12}F
C = k * C. = 8,127x10^{-12}F

(b) not understand

2. Jun 30, 2009

### LowlyPion

3. Jun 30, 2009

### Apprentice123

4. Jun 30, 2009

### LowlyPion

Re: capacitance

You don't need Q.

The dielectric strength is only dependent on distance, and that you are given.

5. Jun 30, 2009

### Apprentice123

Re: capacitance

I do not know the formula. But what you are saying is that:
V / (Dielectric strength) = separation between plates ?

6. Jun 30, 2009

### ideasrule

Re: capacitance

Yes! V=Ed, or V/E=d, for uniform E.

7. Jun 30, 2009

### Apprentice123

Re: capacitance

But I do not have E

Last edited: Jun 30, 2009
8. Jun 30, 2009

### ideasrule

Re: capacitance

What are the units for dielectric strength?

9. Jun 30, 2009

### Apprentice123

Re: capacitance

In this problem I have the dielectric constant (no unit). I do not have the dielectric strength

10. Jun 30, 2009

### LowlyPion

Re: capacitance

The link I gave you earlier has a number for the dielectric strength.

http://en.wikipedia.org/wiki/Dielectric_strength

You know the thickness, so figure the maximum voltage.

11. Jun 30, 2009

### Apprentice123

Re: capacitance

Dielectric Strength = 1,73x10^8

V = 1,73x10^8 * 40x10^{-6} = 6920 V

which symbol to Dielectric strength ?

12. Jun 30, 2009

### LowlyPion

Re: capacitance