Question

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

• 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)

The excess pressure inside the soap bubble is inversely proportional to radius of soap bubble i.e., $p\propto \frac{1}{r},r$ being the radius of bubble. 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.