Two charges are placed as shown in the figure. Where should a third charge be placed so that it remains at rest?

Two charges of $+2\,C$ and $+6\,C$ repel each other with a force of $12\,N$. If each charge is given an additional charge of $-2\,C$,what will be the new force between them?

Two identical conducting spheres carrying different charges attract each other with a force $F$ when placed in air at a distance $d$ apart. The spheres are brought into contact and then returned to their original positions. Now,the two spheres repel each other with a force whose magnitude is equal to the initial attractive force. The ratio between the initial charges on the spheres is:

Two small spheres,each carrying a charge of $+q$,are connected by an insulating string of length $2a$. What is the tension in the string?

If the distance between two point charges $+Q$ and $-Q$ is doubled,what will be the magnitude of the electrostatic force between them?

Two equal charges are separated by a distance $d$. $A$ third charge placed on a perpendicular bisector at $x$ distance will experience maximum Coulomb force when