If $27$ charged water droplets, each of radius $10^{-3} \,m$ and charge $10^{-12} \,C$ coalesce to form a single big spherical drop, then the potential of the big drop is (in $\,V$)

$A$ uniform electric field vector $E$ exists along the horizontal direction as shown. The electric potential at $A$ is $V_A$. $A$ small point charge $q$ is slowly moved from $A$ to $B$ along the curved path as shown. The potential energy of the charge when it is at point $B$ is

In the following diagram,the work done in moving a point charge from point $P$ to points $A$,$B$,and $C$ is $W_A$,$W_B$,and $W_C$ respectively. Then:

$A$ charge of $8 \; mC$ is located at the origin. Calculate the work done in $J$ in taking a small charge of $-2 \times 10^{-9} \; C$ from a point $P (0, 0, 3 \; cm)$ to a point $Q (0, 4 \; cm, 0)$,via a point $R (0, 6 \; cm, 9 \; cm)$.

Four point charges are placed at the vertices of a square of side $2.8 \,m$ as shown in the figure. Find the electric potential at the centre of the square. (in $\,V$)

$A$ proton is accelerated through $50,000 \, V$. Its energy will increase by