The potential at a point,due to a positive charge of $100\,\mu C$ at a distance of $9\,m$,is

Two particles $A$ and $B$ having the same mass have charges $+q$ and $+4q$ respectively. When they are allowed to fall from rest through the same electric potential difference,the ratio of their speeds $v_A$ to $v_B$ will be:

Two electric charges of $9 \mu C$ and $-3 \mu C$ are placed $0.16 \ m$ apart in air. There will be a point $P$ on the line joining the two charges and between them where the electric potential is zero. The distance of $P$ from the $9 \mu C$ charge is: (in $m$)

Define an electron Volt $(eV)$ and express its value in Joule $(J)$ units.

Electric charges $+q$ and $-q$ are placed at points $A$ and $B$ respectively,which are at a distance of $2L$ apart. If $C$ is the midpoint between $A$ and $B$,then the work done in moving a charge $+Q$ along the semi-circle $CRD$ is

The total charge on a uniformly charged spherical shell having radius $R$ is $Q$. Then electric potential at a distance $r = R/2$ from the centre of the shell is . . . . . . .