Angle between equipotential surface and lines of force is.......$^o$

Three point charges $+q, -2q$ and $+q$ are placed at points $(x = 0, y = a, z = 0), (x = 0, y = 0,z = 0)$ and $(x = a, y = 0, z = 0)$ respectively. The magnitude and direction of the  electric dipole moment vector of this charge assembly are

A charge $q$ is placed at the centre of the line joining two equal charges $Q$. The system of the  three charges will be in equilibrium, if $q$ is equal to

Which graph shows variation of electric field of a uniformly charged sphere $w.r.t.$ distance $(r)$ from the centre

Two point charges $+8q$ and $-2q$ are located at $x = 0$ and $x = L$ respectively. The location of a point on the $x-$ axis at which the net electric field due to these two point charges is zero is

Two equal negative charges $-q$ are fixed at points $(0, -a)$ and $(0, a)$ in the $x-y$ plane. A positive charge $Q$ is released from rest at a point $(2a, 0)$. The charge $Q$ will