Difference in the maximum potential capacitance

[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

 

[LowlyPion]

(b) not understand

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

 

[Apprentice123]

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

potential difference of

V = (Q*d)/(E.*A)

I do not have Q

 

[LowlyPion]

potential difference of

V = (Q*d)/(E.*A)

I do not have Q

You don't need Q.

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

 

[Apprentice123]

You don't need Q.

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

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

 

[ideasrule]

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

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

 

[Apprentice123]

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

But I do not have E

 

[ideasrule]

But I do not have E

What are the units for dielectric strength?

 

[Apprentice123]

What are the units for dielectric strength?

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

 

[LowlyPion]

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

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.

 

[Apprentice123]

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.

Dielectric Strength = 1,73x10^8

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


which symbol to Dielectric strength ?

 

[LowlyPion]

which symbol to Dielectric strength ?

Whatever strikes your fancy.