6. [6] A metal plate of area A carries a charge Q. (a) [3] What is the charge on the upper surfaces? (b) [3] What is the electric field just above the upper surface. 7. [20] A second metal plate identical to the one above in problem 6 is placed a distance d below the first and a charge -Q is placed on it. In terms of the quantities given in the problem (Q, A, d), use Gauss's law, to find (a) [3] the electric field between the plates in terms of the Q and A (b) [3] the voltage between the plates (c) [3] the capacitance of the structure. (d) [3] the electric energy of the system d