Given two concentric conducting spheres with radii $0\mathrm{.}2$m and $0\mathrm{.}5$m$.$ In between the two conductors, the region $0\mathrm{.}2$m $<$ r $<0\mathrm{.}4$m is filled with a material with conductivity $1=0\mathrm{.}007$ mhos$/$m$,$ and the region $0\mathrm{.}4$m $<$ r $<0\mathrm{.}5$m is filled with a material with conductivity $2=0\mathrm{.}003$ mhos$/$m$.$