Question

A beaker is filled with liquid solution. A soap bubble of radius $1\text{mm}$ is formed in the bulk of liquid solution. If surface tension of liquid is $1.6\text{N/m}$, find the excess pressure inside the soap bubble.

• A. $1.6\times {10}^3{\text{N/m}}^2$
• B. $3.2\times {10}^3{\text{N/m}}^2$
• C. $0.8\times {10}^{-3}{\text{N/m}}^2$
• D. None of these

Answer 1

The correct option is B $3.2\times {10}^3{\text{N/m}}^2$


We know,
For soap bubble in bulk of the liquid, only one interface is present.
$\therefore \Delta P=\frac{2T}{R}$
Where, $\Delta P$ = Excess pressure
$T=$ Surface tension of liquid
$R=$ radius of bubble
$\therefore \Delta P=\frac{2\times 1.6}{1\times {10}^{-3}}{\text{N/m}}^2$
$=3.2\times {10}^3{\text{N/m}}^2$