Polarized Slab between Parallel Plate Electrode

[Gandhi]

Homework Statement

Find the electric field everywhere for the following permanently polarized structures which do not support any free charge:
(b) Permanently polarized slab $P_0 i_x$ of thickness $b$ placed between parallel plate electrodes in free space at potential difference $V_0$

Homework Equations

$D = ε_0 E + P$
$D = εE$

The Attempt at a Solution

$E_0(s-b) + E_i b = V_0$ where E_0 is the electric field outside the slab and E_i is the electric field inside the slab.
$εE_i = ε_0E_0 + P_0$
From here I was thinking, since I have a coupled equation, I would solve for $E_i$ and $E_0$ but I don't know if the above method will work since the value of ε was not given.
Thanks for the help!

 

[Simon Bridge]

When they say the polarization is permanent - do they mean that it does not depend on the applied field?

 

[Gandhi]

When they say the polarization is permanent - do they mean that it does not depend on the applied field?

It does not specify but I believe that is the case.

 

[Simon Bridge]

So what does that tell you about $\epsilon$?