7. A solid conducting sphere of radius a is positively charged and surrounded by a negatively charged concentric spherical shell of radius b. The charge on the inner sphere is +Q and the charge on the outer sphere is -Q, respectively. The figure to the right shows a cutout cross section of the two concentric conducting spheres. Let r represent the distance from the center of the spheres.e 7b) If the potential difference between the two spheres is Q Q - dne,a B e, b what is the capacitance of the two conducting spheres? [Hint: Your final answer should be written in terms of the electric constant k (or the electric permittivity ,,), the charge @, the radii a and/or b, and the distance from the center r, You do not necessarily need all these quantities in your solution, but these are \"known values\" available for you to write your final answer.) e 7c) What is the potential energy of the two conducting spheres? [Hint: Your final answer should be written in terms of the electric constant k (or the electric permittivity ,), the charge @, the radii a and/or b, and the distance from the center r. You do not necessarily need all these quantities in your solution, but these are \"known values\" available for you to write your final answer.]