The potential difference between the points $P$ and $Q$ in the adjoining circuit will be :-

Calculate the electrostatic potential energy of the system of charges shown in the figure (in $ergs$).

Four capacitors of capacitance $10\,\mu F$ and a battery of $200\, V$ are arranged as shown. How much charge will flow through $AB$ after the switch $S$ is closed? (in $\mu C$)

Two positive charges of magnitude $q$ are placed at the ends of one side of a square of side $2a$. Two negative charges of the same magnitude are kept at the other two corners. Starting from rest,if a charge $Q$ moves from the midpoint of the side with positive charges to the centre of the square,its kinetic energy at the centre of the square is

Six point charges are kept at the vertices of a regular hexagon of side $L$ and centre $O$,as shown in the figure. Given that $K = \frac{1}{4 \pi \varepsilon_0} \frac{q}{L^2}$,which of the following statement$(s)$ is (are) correct?
$(A)$ The electric field at $O$ is $6K$ along $OD$
$(B)$ The potential at $O$ is zero
$(C)$ The potential at all points on the line $PR$ is same
$(D)$ The potential at all points on the line $ST$ is same.

Four capacitors and a battery are connected as shown. The potential drop across the $7 \mu F$ capacitor is $6 \ V$. Then the: