Electric charges of $1\,\mu C$, $-1\,\mu C$, and $2\,\mu C$ are placed in air at the corners $A$, $B$, and $C$ respectively of an equilateral triangle $ABC$ having a side length of $10\,cm$. The resultant force on the charge at $C$ is......$N$

Two similar spheres having $+q$ and $-q$ charge are kept at a certain distance $r$. $A$ force $F$ acts between them. If another similar sphere having $+q$ charge is kept in the middle of the two spheres, then it experiences a force in magnitude and direction as:

Three charges are placed as shown in the figure. The magnitude of $q_1$ is $2.00\, \mu C$,but its sign and the value of the charge $q_2$ are not known. Charge $q_3$ is $+4.00\, \mu C$,and the net force on $q_3$ is entirely in the negative $x-$ direction. The magnitude of $q_2$ 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.........$N$

Two identical charged conducting spheres $A$ and $B$ have their centres separated by a certain distance. Charge on each sphere is $q$ and the force of repulsion between them is $F$. $A$ third identical uncharged conducting sphere $C$ is brought in contact with sphere $A$ first and then with $B$ and finally removed from both. The new force of repulsion between spheres $A$ and $B$ (radii of $A$ and $B$ are negligible compared to the distance of separation so that for calculating force between them they can be considered as point charges) is best given as:

When $4 \ C$,$Q \ C$,and $1 \ C$ electrical charges are placed along a straight line of length $l$ at positions $0$,$\frac{l}{2}$,and $l$ respectively,what are the values of $Q$ such that the net force on the $4 \ C$ charge is zero,and separately,the net force on the $1 \ C$ charge is zero? (in coulomb)