$(10\%)$ Charge $2Q$ is uniformly distributed along a long copper wire of radius $a,$ and the wire is located at the center of a cylindrical copper shell which is in itself with charge $-Q.$ The inner and outer radii for

the shell are $b$ and $c$ respectively. Find the electric field and the electric potential at $($i$)r=ddcc$ respectively. The potential $is$ set $tobe$ zero $atr=d,$ where $dis$ a number greater than $c.b$ and $(iii)c$ respectively. The potential $is$ set $tobe$ zero $atr=d,$ where $dis$ a number greater than $c.a(ii)b$ and $(iii)c$ respectively. The potential $is$ set $tobe$ zero $atr=d,$ where $dis$ a number greater than $c.$