NEET2026PhysicsChapterActual
Two soap bubbles of unequal radii are connected by a narrow hollow tube. Which of the following correctly describes the flow of air between them?
Options
- AAir flows from the smaller bubble to the larger bubble.
- BAir flows from the larger bubble to the smaller bubble.
- CAir does not flow as the system is already in pressure equilibrium.
- DAir flows from the larger to the smaller bubble until their sizes become equal.
Correct answer
A. Air flows from the smaller bubble to the larger bubble.
Step-by-step solution
The excess pressure inside a soap bubble of radius R is given by P = 4T R , where T is the surface tension. Let the radius of the smaller bubble be r and the larger bubble be R , with r The pressure inside the smaller bubble is P₁ = P₀ + 4T r and inside the larger bubble is P₂ = P₀ + 4T R . Since r 4T R , which implies P₁ > P₂ . Air always flows from a region of higher pressure to a region of lower pressure. Therefore, air will flow from the smaller bubble to the larger bubble. Answer: Air flows from the smaller bu