A uniform electric field of $20\, N/C$ exists along the $x$ -axis in a space. The potential  difference $(V_B -V_A)$ for the point $A(4\,m, 2\,m)$ and $B(6\,m, 5\,m)$ is.....$V$

Calculate potential on the axis of a ring due to charge $Q$ uniformly distributed along the ring of radius $R$.

Six charges are placed around a regular hexagon of side length a as shown in the figure. Five of them have charge $q$, and the remaining one has charge $x$. The perpendicular from each charge to the nearest hexagon side passes through the center $O$ of the hexagon and is bisected by the side.

Which of the following statement($s$) is(are) correct in SI units?

$(A)$ When $x=q$, the magnitude of the electric field at $O$ is zero.

$(B)$ When $x=-q$, the magnitude of the electric field at $O$ is $\frac{q}{6 \pi \epsilon_0 a^2}$.

$(C)$ When $x=2 q$, the potential at $O$ is $\frac{7 q}{4 \sqrt{3} \pi \epsilon_0 a}$.

$(D)$ When $x=-3 q$, the potential at $O$ is $\frac{3 q}{4 \sqrt{3} \pi \epsilon_0 a}$.

Two metal spheres $A$ and $B$ of radii $a$ and $b(a < b)$ respectively are at a large distance apart. Each sphere carries a charge of $100 \mu C$. The spheres are connected by a conducting wire, then

$64$ drops of mercury each charged to a potential of $10\,V$. They are combined to form one bigger drop. The potential of this drop will be.......$V$ (Assume all the drops to be spherical)

Three charges $q, \sqrt 2q, 2q$ are placed at the corners $A, B$ and $C$ respectively of the square $ABCD$ of side $'a'$ then potential at point $'D'$