# Physics homework problem - design a capacitor

1. May 13, 2014

### mondroid

Physics homework problem -- design a capacitor

1. The problem statement, all variables and given/known data
An engineer needs to design a capacitor with a capacitance of 1*10-6F using a material with a dielectric constant 260. If the dielectric strength of the material is 8*106 N/C, and the maximum voltage that the capacitor is allowed to handle is 160 volts, what must be the area of the plates?

2. Relevant equations
Q=CV, C=A/(4πkd)

3. The attempt at a solution

A=4πkdC; everything is known except the distance between plates

V=Ed, d=V/E; V is given

E=kq/r2, r=d

d=kq/V

A=4πk2CQ/V

I got A = .113m2 but I'm not sure If I'm doing it right or not. Could some check it for me please. I did not use the dielectric constant and dielectric strength values.

Thank you

2. May 13, 2014

### Simon Bridge

Then you are doing it wrong.

What is important about the maximum voltage?
It is the voltage, above which, the capacitor does something special...

3. May 13, 2014

### butleRonius

Dielectric strength can also be written as$\frac{V}{m}$, and Max Voltage on a capacitor is dielectric strength * distance between the plates.

Hope this helps.