Two electrons are separated by a distance of $1\,\mathop A\limits^o $. What is the coulomb force between them

Two spheres $A$ and $B$ of radius $4\,cm$ and $6\,cm$ are given charges of $80\,\mu c$ and $40\,\mu c$ respectively. If they are connected by a fine wire, the amount of charge flowing from one to the other is

The force between two charges $0.06\,m$ apart is $5\,N$. If each charge is moved towards the other by $0.01\,m$, then the force between them will become………$N$

Point charges $ + 4q,\, – q$ and $ + 4q$ are kept on the $x – $axis at points $x = 0,\,x = a$ and $x = 2a$ respectively, then

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