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JEE Mains · Physics · STD 11 - Surface tension
  • JEE Mains 2024
  • Hard
  • MCQ

A small liquid drop of radius \(R\) is divided into \(27\) identical liquid drops. If the surface tension is \(\mathrm{T}\), then the work done in the process will be _______.

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Answer & Solution

Correct Answer

(A) \(8 \pi R^2 \mathrm{~T}\)

Step-by-step Solution

Detailed explanation

Volume constant

\( \frac{4}{3} \pi \mathrm{R}^3=27 \times \frac{4}{3} \times \pi \mathrm{r}^3 \)

\( \mathrm{R}^3=27 \mathrm{r}^3 \)

\( \mathrm{R}=3 \mathrm{r} \)

\( \mathrm{r}=\frac{\mathrm{R}}{3} \)

\( \mathrm{r}^2=\frac{\mathrm{R}^2}{9}\)

Work done \(=\mathrm{T} \Delta \mathrm{A}\)

\(=27 \mathrm{~T}\left(4 \pi \mathrm{r}^2\right)-\mathrm{T} 4 \pi \mathrm{R}^2\)

\(=27 \mathrm{~T} 4 \pi \frac{\mathrm{R}^2}{9}-4 \pi \mathrm{R}^2 \mathrm{~T}\)

\(8 \pi \mathrm{R}^2 \mathrm{~T}\)

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