Capacitor Voltage breakdown calculations

[hadronboy]

Homework Statement

This is a general problem i have been having but if you are given the relative dielectric strength of a material, (take air, 1.00058986), i have then been told it can only handle a maximum of 3V/micro meter. i have then been given a question a asking what is the breakdown voltage of tantalum, (27) and a ceramic disk (1,000 - 10,000). I am unsure how to work this out

Homework Equations

unsure what to use

The Attempt at a Solution

tried permitivity equations but nothing really worked, i first trying to work out the air example so that i then know the procedure to work out the others

 

[berkeman]

Homework Statement

This is a general problem i have been having but if you are given the relative dielectric strength of a material, (take air, 1.00058986), i have then been told it can only handle a maximum of 3V/micro meter. i have then been given a question a asking what is the breakdown voltage of tantalum, (27) and a ceramic disk (1,000 - 10,000). I am unsure how to work this out

Homework Equations

unsure what to use

The Attempt at a Solution

tried permitivity equations but nothing really worked, i first trying to work out the air example so that i then know the procedure to work out the others

I'm not understanding the technique that they are asking you to use...

For air, you start with the Paschen curve (breakdown versus pressure for gasses):

http://en.wikipedia.org/wiki/Paschen's_law

You might check on the curve at atmospheric pressure to verify the 3V/um number you were given.

But I don't see how simply ratioing with dielectric constant will give you the insulator breakdowns. That certainly tells you how the E-field ratios, but I'm doubtful that it's just E-field that determines the breakdown. Unless they just want you to use that as a simplification...