Deutron and $\alpha - $ particle are put $1\,\mathop A\limits^o $ apart in air. Magnitude of intensity of electric field due to deutron at $\alpha - $ particle is

Charge $q$ is uniformly distributed over a thin half ring of radius $R$. The electric field at the centre of the ring is

A positively charged pendulum is oscillating in a uniform electric field pointing upwards. Its time period as compared to that when it oscillates without electric field

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

A point charge of $10\,\mu C$ is placed at the origin. At what location on the $X$-axis should a point charge of $40\,\mu\,C$ be placed so that the net electric field is zero at $x =2\,cm$ on the $X$-axis ?

Two point charges $q_{1}$ and $q_{2},$ of magnitude $+10^{-8} \;C$ and $-10^{-8}\; C ,$ respectively, are placed $0.1 \;m$ apart. Calculate the electric fields at points $A, B$ and $C$ shown in Figure