A given charge is situated at a certain distance from an electric dipole in the axial position experiences a force $F$ . If the distance of the charge is doubled, the force acting on the charge will be

The four capacitors, each of $25\,\mu F$ are connected as shown in Fig. The $dc$ voltmeter reads $200\,V$. The charge on each plate of capacitor is

A charge $Q$ is placed at each of the opposite corners of a square. A charge $q$ is placed at each of the other two corners. If the electrical force on $Q$ is zero, then $Q/q$ equals

Three charges $4q,\,Q$ and $q$ are in a straight line in the position of $0$, $l/2$ and $l$ respectively. The resultant force on $q$ will be zero, if $Q = $

Two spherical conductors $B$ and $C$ having equal radii and carrying equal charges in  them repel each other with a force $F$ when kept apart at some some distance. $A$ third  spherical conductor having same radius as that of $B$ but uncharged, is brought in contact with $B$, then brought in contact with $C$ and finally removed away from both.  The new force of repulsion between $B$ and $C$ is-

In the given circuit if point $C$ is connected to the earth and a potential of $+2000\,V$ is given to the point $A$ , the potential of $B$ is.....$V$