Question

A square wire frame of side 10 cm is dipped in a liquid of surface tension 28 x ${10}^{-3}N{m}^{-1}$. On taking out, a membrane is formed. What is the force acting on the surface of wire frame?

Answer 1

Length of sqaure shaped wire, l = 10 cm = ${10}^{-1}m$

$T=2.8\times {10}^{-3}n/m$

Force = 2l (both surface)$\times$ Surface tension (T)

$=2\times {10}^{-1}\times 2.8\times {10}^{-3}$

$=5.6\times {10}^{-3}N$