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Question
How much work is required to form a bubble of 2 cm radius from the soap solution having surface tension 0.07 N/m?
Solution
Given:
r = 2 cm = 2 × 10-2 m,
T = 0.07 N/m
To find:
Work required to form a bubble
Solution:
Initial surface area of soap bubble = 0
Final surface area of soap bubble = 2 × 4πr2
∴ Increase in surface area = 2 × 4πr2
The work done = surface tension × increase in surface area
= T × 2 × 4πr2
= 0.07 × 2 × 4 × 3.142 × (2 × 10-2)2
= 7.038 × 10-4 J
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