Question

The adjoining diagram shows three soap bubbles A, B and C prepared by blowing the capillary tube fitted with stop cocks S, $S_1$, $S_2$ and $S_3$ With stop cock S closed and stop cocks $S_1,S_2$ and $S_3$ opened :-

• A. B will start collapsing with volumes of A and C increasing
• B. C will start collapsing with volumes of A and B increasing
• C. C and A will both start collapsing with volumes of B increasing
• D. volumes of A, B, C will becomes equal at equilibrium

Answer 1

Answer: (C)

C and A will both start collapsing with volumes of B increasing

The pressure difference between the inside and outside of a soap bubble is given by the formula,

$P_i-P_o=\frac{4T}{R}$

Thus smaller the radius higher the pressure difference.

Hence the bubble with the smallest radius has the highest pressure.

Hence the pressure inside the soap bubbles is in the order: $P_C>P_A>P_B$

Thus on opening stop cocks $S_1,S_2,and{S}_3$, bubble C and A will start collapsing while B increases.