Fluid Mechanics Viscosity Question 228

Question: The surface tension of soap solution is $ 25\times {{10}^{-3}},N{{m}^{-1}} $ .The excess pressure inside a soap bubble of diameter 1 cm is[AIIMS 1987]

Options:

A) 10 Pa

B) 20 Pa

C) 5 Pa

D)None of the above

Show Answer

Answer:

Correct Answer: B

Solution:

Excess pressure $ \Delta P=\frac{4T}{r} $ $ =\frac{4\times 2\times 25\times {{10}^{-3}}}{1\times {{10}^{-2}}} $ $ =20\ N/m^{2}=20\ Pa $ $ \left[ \text{as }r=\frac{d}{2} \right] $