Question

If two soap bubbles of different radii are connected by a tube:

• A. air flows from the bigger bubble to the smaller bubble till the sizes become equal
• B. air flows from bigger bubble to the smaller bubble till the sizes are interchanged
• C. air flows from the smaller bubble to the bigger
• D. there is no flow of air

Answer 1

Answer: (C)

air flows from the smaller bubble to the bigger

Answer 2

The excess pressure inside the soap bubble is inversely proportional to radius of soap bubble
i.e. $, P \propto 1 / r, r$ being the radius of hubble. It follows that pressure inside a smaller bubble is greater than that inside a bigger bubble. Thus, if these two bubbles are connected by a tube, air will flow from smaller bubble to bigger bubble and the bigger bubble grows at the expense of the smaller one