Question

The potential of a large liquid drop when eight liquid drops are combined is $20V$. Then, the potential of each single drop was

• A. 10 V
• B. 7.5V
• C. 5V
• D. 2.5V

Answer 1

Answer: (A)

Volume of 8 drops = Volume of big drop
$\therefore$ $\left(\frac{4}{3}\pi r^3\right)\times 8=\frac{4}{3}\pi R^3$
$\Rightarrow$ $2r=R$ ...(i)
According to charge conservation
$8q=Q$ ...(ii)
We have $V\propto \frac{1}{r}$
Or $\frac{V_1}{V_2}=\frac{r_2}{n}$
$\Rightarrow$ $\frac{20}{V_2}=\frac{2r}{r}$
$\Rightarrow$ $V_2=10V$