Answer to Question #57331 in Electricity and Magnetism for Pekka

Question

An electric charge is uniformly distributed with volume density
ρ = 10−8 C/m3 between two infinite parallel plates which are d
= 2 cm apart. Calculate the electric flux density D(x) due to this
charge distribution and plot schematically its dependence on x.
Now imagine that a point charge q = 1.5 × 10−8 C is placed in the
median plane (the plane parallel to the two plates, midway between
them) of the charge distribution and determine what is the work
that the electrostatic force has to do in order to move q to a point
P, located outside the region where the charge is distributed, at a
distance h = 3 cm from the nearest plate.