Eight drops of mercury of equal radii and possessing equal charge combine to form a big drop. If the…
Eight drops of mercury of equal radii and possessing equal charge combine to form a big drop. If the capacity of each drop is ' C '. then capacity of the big drop is
4 C
2 C
8 C
16 C
Solution
Volume of big drop $=8 \times$ volume of small drop
$\Rightarrow \frac{4}{3} \pi R^3=8 \times \frac{4}{3} \pi r^2 \Rightarrow R=2 r$
$\therefore \quad$ Capacity of big drop,
$\mathrm{C}^{\prime}=4 \pi \varepsilon_0 \mathrm{R}=4 \pi \varepsilon_0(2 \mathrm{r})=2\left(4 \pi \varepsilon_0 \mathrm{r}\right)=2 \mathrm{C}$