Question:
The amount of work done in blowing a soap bubble such that its diameter increases from $d_1$ to $d_2$ is (T = surface tension of soap solution)
The amount of work done in blowing a soap bubble such that its diameter increases from $d_1$ to $d_2$ is (T = surface tension of soap solution)
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Always multiply by 2 for "bubbles" and 1 for "drops" due to the number of free surfaces.
Updated On: Apr 30, 2026
- $4\pi (d_2^2 - d_1^2) T$
- $8\pi (d_2^2 - d_1^2) T$
- $\pi (d_2^2 - d_1^2) T$
- $2\pi (d_2^2 - d_1^2) T$
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Verified By Collegedunia
The Correct Option is D
Solution and Explanation
Step 1: Concept
Work done $W = T \times \Delta A$. A soap bubble has two surfaces.
Step 2: Area Calculation
$A = 2 \times (4\pi R^2) = 2 \times (4\pi (\frac{d}{2})^2) = 2\pi d^2$
Step 3: Change in Area
$\Delta A = 2\pi d_2^2 - 2\pi d_1^2 = 2\pi (d_2^2 - d_1^2)$
Step 4: Work Done
$W = T \times 2\pi (d_2^2 - d_1^2)$
Final Answer:(D)
Work done $W = T \times \Delta A$. A soap bubble has two surfaces.
Step 2: Area Calculation
$A = 2 \times (4\pi R^2) = 2 \times (4\pi (\frac{d}{2})^2) = 2\pi d^2$
Step 3: Change in Area
$\Delta A = 2\pi d_2^2 - 2\pi d_1^2 = 2\pi (d_2^2 - d_1^2)$
Step 4: Work Done
$W = T \times 2\pi (d_2^2 - d_1^2)$
Final Answer:(D)
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