Two metal spheres have their radii in the ratio of $4:7$. They are put in contact and a charge $8.8 \times 10^{-7} \text{ C}$ is given to the system. Then they are separated so that each can exert no influence on the other. The potential due to the smaller sphere at $60 \text{ m}$ from it in Volt is

Given below are two statements.
Statement $I$ : Electric potential is constant within and at the surface of each conductor.
Statement $II$ : Electric field just outside a charged conductor is perpendicular to the surface of the conductor at every point.
In the light of the above statements,choose the most appropriate answer from the options given below.

Two isolated metallic solid spheres of radii $R$ and $2R$ are charged such that both have the same charge density $\sigma$. The spheres are then connected by a thin conducting wire. If the new charge density of the bigger sphere is $\sigma^{\prime}$,then the ratio $\frac{\sigma^{\prime}}{\sigma}$ is:

Two charged metallic spheres are joined by a very thin metal wire. If the radius of the larger sphere is four times that of the smaller sphere,the electric field near the larger sphere is

$A$ and $B$ are two concentric conducting spherical shells. $A$ is given a positive charge $+Q$ while $B$ is earthed. Then:

An empty thick conducting shell of inner radius $a$ and outer radius $b$ is shown in the figure. If it is observed that the inner face of the shell carries a uniform charge density $-\sigma$ and the outer surface carries a uniform charge density $\sigma'$,if the outer surface of the shell is earthed,then identify the correct statement$(s)$.