NTA Abhyas JEE Main2020PhysicsMechanical Properties of FluidsPractice
A soap bubble has radius R and thickness d ( < < R ) as shown in the diagram. It collapses into a spherical drop. The ratio of excess pressure in the drop to the excess pressure inside the bubble is
Options
- AR 3 d 1 3
- BR 6 d 1 3
- CR 24 d 1 3
- DNone of these
Correct answer
C. R 24 d 1 3
Step-by-step solution
The volume of soap solution in a bubble = 4 π R 2 d now we make a drop 4 π R 2 d = 4 3 π r 3  ⇒  r = 3 R 2 d 1 / 3 Excess pressure initially = 4 S R Excess pressure finally = 2 S r = 2 S 3 R 2 d 1 / 3 Ratio = R 24 d 1 3