Figure 1. Cross section of two concentric charged spherical shells. This inner shell has radius r and charge +Q and the outer shell has radius r + d and charge Q. Two concentric, thin, hollow spheres with radii r and r + d are charged with equal and opposite charges. +Q is placed on the inner sphere and Q is placed on the outer sphere as shown in the diagram. In this problem use 60 rather than Coulomb's constant in your answers. Part 1) Write an expression to describe the magnitude of the electric field between the two spheres at a radius R, where r