Twenty-seven drops of the same size are charged at $220 \, V$ each. They combine to form a bigger drop. Calculate the potential of the bigger drop (in $V$).

In the following diagram,the charge and potential difference across the $8\,\mu F$ capacitor will be nearly:

The charge on the $4\,\mu F$ capacitor in the given circuit is .... in $\mu C$.

Two capacitors of capacitances $1\ \mu F$ and $3\ \mu F$ are charged to the same voltages $5\ V$. They are connected in parallel with oppositely charged plates connected together. Then:

$A$ radioactive substance in the form of a metallic sphere of diameter $10^{-3} \ m$ emits particles at a constant rate of $6.25 \times 10^{10}$ particles per second. If the sphere is electrically isolated,how long will it take for its potential to increase by $1.0 \ V$? Assume that $80\%$ of the emitted particles escape from the surface. The time taken is $... \mu s$.

Three uncharged capacitors of capacitances $C_1$,$C_2$,and $C_3$ are connected as shown in the figure. If $A$,$B$,and $C$ are at potentials $V_1$,$V_2$,and $V_3$ respectively,then the potential at point $O$ is: