Question

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

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

Hint:

Air flows from the smaller bubble to the larger one because the pressure inside the smaller bubble is higher due to its smaller radius.

Answer 1

The Correct Option is A

Step 1: The pressure inside a soap bubble is higher than the outside pressure due to surface tension. The pressure inside a bubble is given by: \[ P = \frac{4T}{r}, \] where \( T \) is the surface tension, and \( r \) is the radius of the bubble. 
Step 2: For two bubbles connected by a tube, the smaller bubble will have a higher pressure inside due to its smaller radius. Therefore, air will flow from the higher-pressure bubble (smaller one) to the lower-pressure bubble (larger one). 
Step 3: Hence, air flows from the smaller bubble to the bigger bubble.