Add conductor between infinite sheet

[CH1991]

Homework Statement

Please check attachment or picture below
http://i.imgur.com/ALG5d.png

Homework Equations

The Attempt at a Solution

Probably I should consider it as a capacitor? For a conductor, is that means no charge inside, charges are all on surface?

Thanks!

 

[Spinnor]

I think inserting the conducting slab has the same effect as moving the two charged sheets closer together? See,

http://en.wikipedia.org/wiki/Electric_potential#In_electrostatics

Good luck!