Question

A beaker is filled with liquid having surface tension $0.07\text{N/m}$. If a bubble of radius $0.5\text{mm}$ is formed at depth $h=1\text{m}$ below the free surface, then find difference between the pressure acting inside the bubble and free surface.
(Density of liquid is $1000{\text{kg /m}}^3)$

• A. $0.28\times {10}^4{\text{N/m}}^2$
• B. $0.56\times {10}^4{\text{N/m}}^2$
• C. $1.028\times {10}^4{\text{N/m}}^2$
• D. $2.014\times {10}^4{\text{N/m}}^2$

Answer 1

The correct option is C $1.028\times {10}^4{\text{N/m}}^2$


We know,
$\Delta P=\frac{2T}{R}+\rho gh$
Where,
$\Delta P$ = Pressure difference
$T$ = Surface tension of liquid
$R$ = Radius of bubble
$\rho$ = Density of liquid
$\therefore \Delta P=\frac{2\times 0.07}{0.5\times {10}^{-3}}+{10}^3\times 10\times 1$
$=0.28\times {10}^3+{10}^4$
$=1.028\times {10}^4{\text{N/m}}^2$