Three concentric spherical metallic shells A, B and C of radii $\mathrm{a}=7 \mathrm{~cm}, \mathrm{~b}=17…
Three concentric spherical metallic shells A, B and C of radii $\mathrm{a}=7 \mathrm{~cm}, \mathrm{~b}=17 \mathrm{~cm}$ and ' $\mathrm{c}$ ' $(a < b < c)$ have surface charge densities $\sigma,-\sigma$ and $\sigma$ respectively. If $A$ and $C$ are at the same potential, then the value of ' $\mathrm{c}$ ' is