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Question
How much amount of work is done in forming a soap bubble of radius r?
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Solution
We know that a bubble has two surfaces in contact with air, so the total surface area of the bubble will be
= 2 × (4πr2)
= 8πr2
Now, work done = Surface tension × Increase in surface area
= T × (8πr2 − 0)
= 8πr2T
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