For a uniformly charged ring of radius $R$, the electric field on its axis has the largest magnitude at a distance $h$ from its centre. Then value of $h$ is

A vertical electric field of magnitude $4.9 \times 10^{5} N / C$ just prevents a water droplet of a mass $0.1\, g$ from falling. The value of charge on the droplet will be  ........ $\times 10^{-9} \;C$ $\left(\right.$ Given $\left.g =9.8 m / s ^{2}\right)$

Charge $Q$ is distributed non-uniformly over a ring of radius $R, P$ is a point on the axis of ring at a distance $3R$ from its centre. Which of the following is a wrong statement.

Six charges, three positive and three negative of equal magnitude are to be placed at the vertices of a regular hexagon such that the electric field at $O$ is double the electric field when only one positive charge of same magnitude is placed at $R$. Which of the following arrangements of charges is possible for $P,\,Q,\,R,\,S,\,T,\,$ and $U$ respectively

A circular ring carries a uniformly distributed positive charge. The electric field $(E) $ and potential $ (V) $ varies with distance $(r)$ from the centre of the ring along its axis as

Two point charges of $20\,\mu \,C$ and $80\,\mu \,C$ are $10\,cm$ apart. Where will the electric field strength be zero on the line joining the charges from $20\,\mu \,C$ charge......$m$