A metal sphere with radius 1.40 cm is supported on an insulating stand at the center of a hollow, metal, spherical shell with radius rb = 9.10 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 420 V, with the inner sphere at higher potential.

A metal sphere with radius 1.40 cm is supported on an insulating stand at the center of a hollow, metal, spherical shell with radius rb = 9.10 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 420 V, with the inner sphere at higher potential.