- #1

breez

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## Homework Statement

You are asked to construct a capacitor having a capacitance near 1 nF and a breakdown potential in excess of 13000 V. You think of using the sides of a tall plastic drinking glass as a dielectric (with a dielectric constant 5.2 and dielectric strength 12 kV/mm), lining the inside and outside curved surfaces with aluminum foil to act as the plates. The glass is 14 cm tall with an inner radius of 3.17 cm and an outer radius of 3.38 cm. (a) What are the capacitance and (b) breakdown potential in kilovolts of this capacitor?

## Homework Equations

[tex]C = \frac{2\pi \epsilon_0 \kappa L}{\ln \frac{b}{a}}[/tex]

## The Attempt at a Solution

I used the above formula to compute the capacitance, which is pretty much plug and chug.

I don't know how to compute breakdown potential though. I multiplied the dielectric strength by the thickness of the capacitor (difference in radii in mm) but that was marked wrong.

Anyone know how to properly compute the breakdown potential? This problem has me stumped.