PROBLEMS TO BE WRITTEN UP AND TURNED IN AT RECITATION

     This problem is due at your first recitation meeting after WED 9/29.
     The problem should be written on a single sheet of paper (front and back), 
     or if multiple sheets are used, staple them together.  For full credit,
     the work must be neat, with clearly labeled diagrams.  The labels must
     be in BOTH words and symbols.  For each part of each problem, you must 
     BRIEFLY explain your strategy in words, as well as neatly showing your 
     physics equations and math, with proper units. 

         E2.  An infinitely long rod of radius R carries a uniform
              volume charge density rho (rho > 0).
              (a) Show how to use Gauss' Law to prove that the
                  electric field inside this rod points radially
                  outward and has magnitude 

                            E = (rho*r)/(2*epsilon_0). (10 points)
               
              (b) Find the potential difference between a initial
                  radial position r_i and a final radial position
                  r_f; i.e. find an expression for the potential
                  at r_i subtracted from the potential at r_f.
                  (16 points)

              (c) Choose potential equal zero at the central axis
                  of the rod and find the potential as a function
                  of r inside the rod (i.e. for r < R).  Make a
                  graph of your resulting potential function (plot
                  V versus r).  (7 points)

              (d) Instead of the case in (c), choose potential equal
                  zero at the surface of the rod (i.e. at r=R) and
                  find the potential as a function of r inside the
                  rod (i.e. for r < R).  Again make a graph of your
                  resulting potential function (plot V versus r).
                  (7 points)