Ahuge (essentially infinite) horizontal nonconducting sheet 10.0 cm thick has charge uniformly spread over both faces. the upper face carries +95.0 nc/m2 while the lower face carries -25.0 nc/ m2. what is the magnitude of the electric field at a point within the sheet 2.00 cm below the upper face?

7.91 * 10^3 N/C

Explanation: In order to solve this problem we have to use the Gaussian law, in both charged surface for the infinite plane.

So inside the non conducting sheet we apply teh superposition principle adding the electric field from each charged surface.

Then we have

Eupper=σ+/εo

Ebottom= σ-/εo

Adding the electric fields we have:

E inside= Eupper-Ebottom=(1/εo)*(σ+-σ-)= (1/8.85* 10^-12)*70 nC/m^2= 7.91* 10^3N/C

no. dot product   =0 when vecs at right angles

d. air pressure decreases as altitude increases.