Question

Work done in increasing size $10\times 11cm$ from $10cm\times 6cm$ of a soap film $3.0\times {10}^{-4}Joule$. Find out the surface tension of the film.

Answer 1

Effective increase in surface area

$\Delta A=2(A_2-A_1)=2[10\times 11-10\times 6]c{m}^2$

$=2\times 10(11-6)c{m}^2=2\times 10\times 5c{m}^2$

$=100c{m}^2$

$=100\times {10}^{-4}{m}^2$

$=1\times {10}^{-2}{m}^2$