Two identical metal balls of radius $r$ are at a distance $a (a >> r)$ from each other and are charged, one with potential $V_1$ and other with potential $V_2$. The charges $q_1$ and $q_2$ on these balls in $CGS$ esu are
${q_1} = \frac{{r{V_1} + a{V_1}}}{{{r^2} + {a^2}}},{q_2} = \frac{{r{V_1} + a{V_2}}}{{{r^2} + {a^2}}}$
${q_1} = \frac{1}{k}\left( {\frac{{r{V_2} - a{V_1}}}{{{r^2} - {a^2}}}} \right)ra,{q_2} = \frac{1}{k}\left( {\frac{{r{V_1} - a{V_2}}}{{{r^2} - {a^2}}}} \right)ra$
${q_1} = \frac{{a{V_2}}}{{k\left( {{r^2} - {a^2}} \right)}},{q_2} = \frac{{r{V_1}}}{{k\left( {{r^2} - {a^2}} \right)}}$
${q_1} = \frac{{r{V_1}}}{{k\left( {{r^2} - {a^2}} \right)}},{q_2} = \frac{{r{V_2}}}{{\left( {{r^2} - {a^2}} \right)k}}$
Let $V$ and $E$ are potential and electric field intensity at a point then
$N$ identical spherical drops charged to the same potential $V$ are combined to form a big drop. The potential of the new drop will be
A spherical conductor of radius $2\,m$ is charged to a potential of $120\,V.$ It is now placed inside another hollow spherical conductor of radius $6\,m.$ Calculate the potential to which the bigger sphere would be raised......$V$
A charge of total amount $Q$ is distributed over two concentric hollow spheres of radii $r$ and $R ( R > r)$ such that the surface charge densities on the two spheres are equal. The electric potential at the common centre is
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 $\frac{3 q}{4 \sqrt{3} \pi \epsilon_0 a}$.