Four charges,each of value $Q = \frac{10}{3} \times 10^{-9} \ C$,are placed at the four corners of a square of side $a = 8 \ cm$. What is the electric potential at the center of the square?

Assertion $(A)$: The work done by the electrostatic force is zero when a point charge moves in a circular path around another charge.
Reason $(R)$: The dot product of force and displacement vectors gives work done.

As shown in the figure,on bringing a charge $Q$ from point $A$ to $B$ and from $B$ to $C$,the work done is $2 \, J$ and $-3 \, J$ respectively. The work done to bring the charge from $C$ to $A$ is (in $, J$)

The electric charges $+2q$, $+2q$, $-2q$ and $-2q$ are placed at the corners of a square of side $2L$ as shown in the figure. The electric potential at point $A$, midway between the two charges $+2q$ and $+2q$, is $(\epsilon_0 = \text{permittivity of free space})$

If four charges $+12 \text{ nC}, -20 \text{ nC}, +32 \text{ nC}$ and $-15 \text{ nC}$ are arranged at the four vertices of a square of side $\sqrt{2} \text{ m}$,then the net electric potential at the centre of the square due to these four charges is (in $\text{ V}$)

Two charges $3 \times 10^{-8} \; C$ and $-2 \times 10^{-8} \; C$ are located $15 \; cm$ apart. At what point on the line joining the two charges is the electric potential zero? Take the potential at infinity to be zero.