A metal sphere with radius $1\mathrm{.}30$ cm is supported on an insulating stand at the center of a hollow, metal, spherical shell with radius rb $=9\mathrm{.}30$ cm$.$ Charge $+$q is put on the inner sphere and charge $$q on the outer spherical shell. The magnitude of q is chosen to make the potential difference between the spheres $460$ V$,$ with the inner sphere at higher potential.