Correct Answer - Option 4 : 0.0125 N/m
Concept:
Surface tension on a liquid droplet (Spherical droplet of water): Pressure intensity inside the droplet:
\(p = \frac{{4\sigma }}{d}\)
Surface tension on a hollow bubble (Soap bubble): Pressure intensity inside the droplet:
\(p = \frac{{8\sigma }}{d}\)
where σ is the surface tension of the liquid.
Calculation:
Given:
d = 40 mm, ΔP = 2.5 N/m2
\({\rm{Δ }}P = \frac{{8\sigma}}{d}\)
\(\sigma = \frac{{Δ P\times d}}{8 } =\frac{{40\times 0.0025}}{8 }= 0.0125\) N/m.
