Question

The surface energy of a liquid drop is u. It is splitted into 103 equal droplets. Then its surface energy becomes:

• A. u
• B. 10u
• C. 100u
• D. 1000u

Answer 1

The correct option is B

10u

Surface energy $\left(U\right)=T.4\pi R^2$
This big drop of radii R is splitted into 10^3 small droplets of radius r
$\frac{4}{3}\pi R^3={10}^3\times \frac{4}{3}\pi r^3$
R=10 r
$E_1={10}^3\times 4\pi \times r^2\times T\therefore r=\frac{R}{10}{E}_1=10U$