Find the electric potential at the origin due to the given distribution of charges.

$A$ particle $A$ has a charge of $+q$ and a particle $B$ has a charge of $+9q$. Both particles have the same mass $m$. If both particles are released from rest through the same potential difference,the ratio of their speeds will be .......

$A$ cube of side $b$ has a charge $q$ at each of its vertices. Determine the potential and electric field due to this charge array at the centre of the cube.

$A$ and $C$ are concentric conducting spherical shells of radius $a$ and $c$ respectively. $A$ is surrounded by a concentric dielectric of inner radius $a$,outer radius $b$ and dielectric constant $k$. If sphere $A$ is given a charge $Q$,the potential at the outer surface of the dielectric (at radius $b$) is:

$A$ spherical shell of radius $5 \ cm$ is charged to a potential of $10 \ V$ on its surface. The potential at the center of the shell will be ...... $V$.

$A$ ball of mass $1\, g$ and charge $10^{-8}\, C$ moves from a point $A$,where the potential is $600\, V$,to a point $B$,where the potential is $0\, V$. The velocity of the ball at point $B$ is $20\, cm/s$. The velocity of the ball at point $A$ will be: