A central brass ball and a concentric brass shell form a spherical capacitor. The central brass ball has a radius R₁ and the shell has an inner radius of 5.10 cm. If a voltage of 180 V is applied across the plates, the central ball and the shell are charged with 5.00 nC and -5.00 nC, respectively. What are i) the capacitance (C) of the device, ii) the numerical value of R₁, and iii) the electric field (E) at the surface of the central ball?