$A$ charge $Q$ is to be divided between two objects. The values of the charges on the objects so that the electrostatic force between them will be maximum is

Two identical charges are separated by a distance $d$. $A$ third charge is placed on their perpendicular bisector at a distance $x$. For the third charge to experience maximum force,the value of $x$ is:

Two particles with charges $+3.72 \mu C$ and $+1.86 \mu C$ are at some distance apart. If $20 \%$ of the charge is transferred from the first particle to the second particle,then the electrostatic force between them is

Charges $q, 2q, 3q,$ and $4q$ are placed at the corners of a square as shown in the figure. $A$ charge $q_0$ is placed at its center. Find the net force on the charge $q_0$.

$A$ point charge $q_1$ exerts a force $F$ upon another point charge $q_2$. If a third charge $q_3$ is placed near the charge $q_2$, then the force that charge $q_1$ exerts on the charge $q_2$ will be

Two identical spheres each of radius $R$ are kept at a center-to-center spacing of $4R$ as shown in the figure. They are charged,and the electrostatic force of interaction between them is first calculated assuming them to be point-like charges at their centers $(F_c)$,and the force is also measured experimentally $(F_m)$. ($F_c$ and $F_m$ denote the magnitude of the force.)