Question

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

(a) Air flow 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

I had been asked this question during an interview.

My question is taken from Thrust of a Liquid in chapter Mechanical Properties of Solids of Engineering Physics I

Answer 1

Correct answer is (c) Air flows from the smaller bubble to the bigger

The explanation: The excess pressure inside of a soap bubble is inversely proportional to its radius. So, the pressure is more inside the smaller bubble than the bigger bubble. When these two bubbles are connected by a tube, air will flow from the smaller bubble to the bigger bubble.