A spherical drop of liquid splits into 1000 identical spherical drops. If ' $\mathrm{E}_1$ ' is the surface…

A spherical drop of liquid splits into 1000 identical spherical drops. If ' $\mathrm{E}_1$ ' is the surface energy of the original drop and ' $\mathrm{E}_2$ ' is the total surface energy of the resulting drops, then $\frac{E_1}{E_2}=\frac{x}{10}$. Then value of ' $x$ ' is
  1. 9
  2. 7
  3. 3
  4. 1

Solution

$\begin{array}{ll} & r=\text { Radius of small drop } \\ & R=\text { Radius of bigger drop } \\ \therefore \quad & \frac{4}{3} \pi R^3=\frac{4}{3} \pi(1000) r^3 \\ \therefore \quad & R=10 r \\ & E_1=T_1^2=T\left(4 \pi R^2\right) \\ & E_2=n A_2^2=1000 \times T\left(4 \pi r^2\right) \\ \therefore \quad & \frac{E_1}{E_2}=\frac{R^2}{1000 r^2}=\frac{(10 r)^2}{1000 r^2} \\ \therefore \quad & \frac{E_1}{E_2}=\frac{1}{10} \\ \therefore \quad & x=1\end{array}$ /

Asked in: MHT CET 2023 (12 May Shift 1)

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