$A$ hollow metal sphere of radius $R$ is charged with a charge $Q$. The electric potential and intensity inside the sphere are respectively

Two metallic concentric shells are shown. Before closing the switch,the charge on the inner shell is $Q$ and the charge on the outer shell is $2Q$. The potential at point $A$ is $V$. What will be the potential at the same point after closing the switch?

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.

For a spherical shell,which of the following statements is correct?

Shown in the figure are two point charges $+Q$ and $-Q$ inside the cavity of a spherical shell. The charges are kept near the surface of the cavity on opposite sides of the centre of the shell. If $\sigma_1$ is the surface charge density on the inner surface and $Q_1$ is the net charge on it,and $\sigma_2$ is the surface charge density on the outer surface and $Q_2$ is the net charge on it,then:

Which of the following statements is always true for a charged conductor?
$(1)$ The electric field just outside the surface is parallel to the surface.
$(2)$ $E_{in} = 0$
$(3)$ Electric field lines are perpendicular to the equipotential surface.