A conducting slab (think of a large flat sheet of metal) is large compared to the size of individual particles and molecules and carries an excess positive charge.
a) Where does the excess charge reside?
b) What is the electric field inside the conductor?
c) Suppose we were able to inject charged particles into the slab so that their initial velocity was parallel to the long sides of the slab. What is the acceleration of these particles? (Assume the charged particles do no interact with the molecules that make up the lattice of the conductor).