An air bubble of radius 0.1 cm lies at a depth of 20 cm below the free surface of a liquid of density 1000 kg/m3. If the pressure inside the bubble is 2100 N/m2 greater than the atmospheric pressure, then the surface tension of the liquid in SI unit is (use g=10 m/s2)
- 0.02
- 0.05
- 0.25
- 0.1
Answer
(2) 0.05
Solution
A bubble inside a liquid has one surface: Pin-Patm= gh+ 2Sr.
[figure]
2100=1000 10 0.2+ 2S10-3
2S10-3=100 S=0.05 N/m
Answer: (2)