Question:medium

The work done in splitting a water drop of radius R into 64 droplets is ($T=$ surface tension)

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Work Done for $n$ droplets: $W = 4\pi TR^2(n^{1/3} - 1)$.
Updated On: Jun 19, 2026
  • $6\pi TR^{2}$
  • $24\pi TR^{2}$
  • $12\pi TR^{2}$
  • $16\pi TR^{2}$
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The Correct Option is C

Solution and Explanation

Step 1: Understanding the Question:
Work is done to increase the surface area of the water. We must find the change in area.

Step 2: Key Formula or Approach:

1. Conservation of volume: \( V = n v \).
2. Work done \( W = T \Delta A = T (n \cdot 4\pi r^2 - 4\pi R^2) \).

Step 3: Detailed Explanation:

Volume of large drop \( = 64 \times \) Volume of small drop.
\[ \frac{4}{3}\pi R^3 = 64 \left( \frac{4}{3}\pi r^3 \right) \implies R^3 = 64 r^3 \implies r = \frac{R}{4} \]
Change in area \( \Delta A = 64(4\pi r^2) - 4\pi R^2 \).
Substitute \( r = R/4 \):
\[ \Delta A = 64 \left[ 4\pi \left( \frac{R}{4} \right)^2 \right] - 4\pi R^2 \]
\[ \Delta A = 64 \left[ \frac{4\pi R^2}{16} \right] - 4\pi R^2 \]
\[ \Delta A = 16\pi R^2 - 4\pi R^2 = 12\pi R^2 \]
Work done \( W = T \Delta A = 12\pi T R^2 \).

Step 4: Final Answer:

The work done is \( 12\pi T R^2 \).
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