Q 11-09-022NEETJEE MainMedium
A soap bubble in air and an air bubble inside the same soap solution have the same radius. The ratio of the excess pressure inside the soap bubble to that inside the air bubble is
Answer: (D) $2 : 1$
Concept. Excess pressure: $\dfrac{4T}{r}$ for a soap bubble (two surfaces), $\dfrac{2T}{r}$ for an air bubble in liquid (one surface).
Step 1. Ratio. $\dfrac{4T/r}{2T/r} = 2 : 1$.
Answer. $2 : 1$ (Option D).
Solution by Sreeraj P, M.Sc Physics