$A$ negative point charge is placed at point $A$ as shown in the figure. The charge is:

Two identical charged spheres are suspended from a common point by two massless strings of length $l$. Initially,they are at a distance $d$ $(d << l)$ due to mutual repulsion. The charge begins to leak from both spheres at a constant rate. As a result,the spheres approach each other with a velocity $v$. Then,the velocity $v$ as a function of the distance $x$ between them is:

Two free point charges $+q$ and $+4q$ are a distance $R$ apart. $A$ third charge is so placed that the entire system is in equilibrium. Then the third charge is :-

$F_g$ and $F_e$ represent the gravitational and electrostatic forces,respectively,between two electrons situated at a distance of $10 \ cm$. The ratio of $F_g/F_e$ is of the order of:

Two point charges $4\,\mu C$ and $-1\,\mu C$ are kept at a distance of $3\ m$ from each other. What is the electric potential at the point where the electric field is zero?

$A$ particle of mass $m$ and charge $q$ is thrown in a region where uniform gravitational field and electric field are present. The path of the particle: