Question

A thin liquid film formed between a $U$-shaped wire and light slider supports a weight of $1.5\times {10}^{-2}N$ (see figure). If the length of the slider $30cm$ and its weight negligible, then the surface tension of the liquid film is:

Answer 1

Given,

Weight, $1.5\times {10}^{-2}N$

Length, $L=30cm=0.3m$

Weight = tension x length

$1.5\times {10}^{-2}=T\times 0.3$

$T=0.05N{m}^{-1}$

Hence, tension is $0.05N{m}^{-1}$ .