A solid metallic sphere of radius r is charged to a voltage V. It is enclosed by a thin spherical shell of radius 2r. If q is the charge on the sphere and the shell each, the potential difference between them will be x V2. What is x?
Charge on the inner sphere is, q = cV = 4πϵ∘rV
The potential difference between the two spheres is,
V' = V1−V2 = q4πϵ∘(1r−12r)=q4πϵ∘12r=V2