Consider the electric potential a distance x above the center of a ring of charge Q with a radius R surrounded by another ring of charge with a radius 2R as in the figure. (a) (6 points) What is the charge on the larger ring if the potential at x is 0? (b) (4 points) Using the charge you determined from part a, what would the potential at a distance x/2 from the center be (if you were unable to determine a charge in part a, just assign it a value of Qunk)? Put your solution in terms of Q, R, x, and any physical constants. X R 2R ??