Question $7$

$2$ pts

A solid metal sphere of radius $r$ is inside a metal concentric spherical shell of inner radius $2r$ and outer radius $3r.$ A charge is place on the solid metal sphere and it is found that the potential at its surface is $V_1($at $r)$ and that the potential at the outer surface of the spherical shell is $V_3($at $3r).$ In terms of $V_1$ and $V_3,$ what is the potential at the inner surface of the metal shell $($at $2r)?$

$3\frac{V_1}{2}$

V$/3$

$V_1$

$2V_{\frac{3}{2}}$