Question

The surface tension of soap solution is $0.03\text{N/m}$. The work done in blowing to form a soap bubble of surface area $40{\text{cm}}^2$ is:

• A. $1.2\times {10}^{-4}\text{J}$
• B. $2.4\times {10}^{-4}\text{J}$
• C. $12\times {10}^{-4}\text{J}$
• D. $24\times {10}^{-4}\text{J}$

Answer 1

The correct option is B $2.4\times {10}^{-4}\text{J}$

In case of soap bubble, two interfaces are present.
$\therefore W=T\times 2\times \Delta A$
$=0.03\times 2\times 40\times {10}^{-4}$
$=2.4\times {10}^{-4}\text{J}$