When a conducting soap bubble is negatively charged,then:

$A$ charge $q$ is distributed uniformly on the surface of a sphere of radius $R$. It is covered by a concentric hollow conducting sphere of radius $2R$. What will be the charge on the outer surface of the hollow sphere if it is earthed?

$A$ spherical conductor of radius $2 \, m$ is charged to a potential of $120 \, V$. It is now placed inside another hollow spherical conductor of radius $6 \, m$. Calculate the potential to which the bigger sphere would be raised. (in $, V$)

$A$ solid spherical conducting shell has an inner radius $a$ and an outer radius $2a$. At the center of the shell is located a point charge $+Q$. What must the excess charge of the shell be in order for the charge density on the inner and outer surfaces of the shell to be exactly equal?

Two spheres of radius $a$ and $b$ respectively are charged and joined by a wire. The ratio of the electric field at the surfaces of the spheres is

Can there be a potential difference between two adjacent conductors carrying the same charge?