*7. The electric potential energy of a uniformly charged square disk of length D and total charge is Q² UD 3.525- (c.g.s. units, approximate). The electric potential energy of a uniformly charged circular disk of radius R and total charge is UR (c.g.s. units, exact). a) Determine the relationships between the radius of the circle the length of a side of the small square and the length of a side of the big square, which are shown in the figure. 8 Q² = 3T R b) With the same surface charge density for all three surfaces (big square, circle and small square), rank the electric potential energies in increasing order of magnitude. Show all work.

*7. The electric potential energy of a uniformly charged square disk of length D and total charge is Q² UD 3.525- (c.g.s. units, approximate). The electric potential energy of a uniformly charged circular disk of radius R and total charge is UR (c.g.s. units, exact). a) Determine the relationships between the radius of the circle the length of a side of the small square and the length of a side of the big square, which are shown in the figure. 8 Q² = 3T R b) With the same surface charge density for all three surfaces (big square, circle and small square), rank the electric potential energies in increasing order of magnitude. Show all work.