Question

Energy needed in breaking a drop of radius $R$ into $n$ drops of radii $r$ is given by

• A. $4\pi T\left(n{r}^2-R^2\right)$
• B. $\frac{4}{3}\pi \left(r^{3}n-R^2\right)$
• C. $4\pi T\left(R^2-n{r}^2\right)$
• D. $4\pi T\left(n{r}^2+R^2\right)$

Answer 1

Answer: (A)

Energy needed $=$ Increment in surface energy
=( surface energy of $n$ small drops) $-$ (surface energy of one big drop)
$=n4\pi r^{2}T-4\pi R^{2}T$
$=4\pi T\left(n{r}^2-R^2\right)$