1. An application of GAUSS’S theorem.
to an infinite charged sheet with charge density sigma
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I get 13,559 V/m.
I think that the field is UNIFORM between the sheet surfaces, so it’s the same at 2cm as at 3cm, I THINK.

2. khally92
A huge (essentially infinite) horizontal nonconducting sheet 10.0 cm thick has charge uniformly spread over both faces. The upper face carries nC/m2 while the lower face carries nC/ m2. What is the magnitude of the electric field at a point within the sheet 2.00 cm below the upper face? (e0 = 8.85 × C2/N · m2). (Note: even a non conducting sheet can have only surface charges, they do not always have to be uniformly charged)