What is the maximum electric field in the system?

[john88]

Homework Statement

Two parallel plates are connected to a constant electrostatic potential.
Half the space between the plates is filled whit air, one quarter whit a conductor and the fourth quarter whit a dielectric whit realtive permittivity of 80. What is the maximum electric field in the system?

Homework Equations

Between the plates $$E = \frac{V}{d}$$ V = potential difference and d = distance between plates.

The Attempt at a Solution

Well first I think that the air will "break" first. I do also think that I need to calculate the flux density first, however I am not sure how to procced

 

[john88]

I posted a picture at the problem...anyway how do I begin to calculate the electric field? Just to use E = V/d doesn't cut it, I need to incorporate the dielectric constants also

http://img297.imageshack.us/img297/5145/namnlsvvvvun4.th.jpg

 

[badphysicist]

It's just two capacitors in series.. one with dielectric and one without (and different dimensions).