If the potential at the centre of a uniformly charged hollow sphere of radius $R$ is $V$,then the electric field at a distance $r$ from the centre of the sphere is $(r > R)$.

Two point unlike charges having magnitudes $+16 \mu C$ and $-9 \mu C$ are separated by a distance of $10 \ cm$ in air. The resultant electric field will be zero at a distance of . . . . . . from the $-9 \mu C$ charge. (in $cm$)

$A$ thin infinite sheet charge and an infinite line charge of respective charge densities $+\sigma$ and $+\lambda$ are placed parallel at $5 \ m$ distance from each other. Points $P$ and $Q$ are at $\frac{3}{\pi} \ m$ and $\frac{4}{\pi} \ m$ perpendicular distance from the line charge towards the sheet charge,respectively. $E_P$ and $E_Q$ are the magnitudes of the resultant electric field intensities at points $P$ and $Q$,respectively. If $\frac{E_P}{E_Q} = \frac{4}{a}$ for $2|\sigma| = |\lambda|$,then the value of $a$ is ...........

$A$ uniformly charged sphere has a total charge $Q$ and radius $R$. The electric field $E$ is a function of the distance $r$ from the center. Which of the following graphs represents this relationship?

The maximum value of the electric field on the axis of a charged ring having charge $Q$ and radius $R$ is:

$A$ negative charge $-q$ is placed at the midpoint between two fixed equal positive charges $Q$,separated by a distance $2d$. If the negative charge is given a small displacement $x$ $(x \ll d)$ perpendicular to the line joining the positive charges,how will the net force $(F)$ acting on it approximately depend on $x$?