$A$ point charge is kept at the centre of a metallic insulated spherical shell. Then:

Two insulated charged spheres of radii $20\,cm$ and $25\,cm$ respectively and having an equal charge $Q$ are connected by a copper wire,then they are separated.

$A$ dipole consisting of two charges $\pm q$ separated by a distance $2a$ is placed with its centre at a distance $D$ from the center of a grounded conducting sphere of radius $R$ $(D \gg a)$. When the dipole moment vector is perpendicular to the line joining the two centres (those of the dipole and sphere),the total charge induced on the sphere is:

What is earthing or grounding in household electrical circuits?

Two metallic spheres of radii $a$ and $b$ are placed far away from each other and are connected by a thin conducting wire. The total charge on them is $Q$. Calculate the potential of each sphere.

Five identical conducting plates,each of face area $A$,are placed parallel to each other with a separation of $d$ between two adjacent plates as shown in the figure. The plates $M$ and $N$ are given charges $Q_1$ and $Q_2$ respectively and the remaining plates are neutral. If the outermost plates are grounded,the potential difference between the plates $M$ and $N$ is . . . . . .