A thin soap film is formed on a U shaped wire loop having a slider (of negliglibe mass) of length 10 cm. it is found that the film can support a weight of 0.012 N, before it breaks. What is the surface tension of the film ?

Answer

`^.06 Nm^(-1)`

Explanation

Here, l = 10 cm = 0.10 cm, F = 0.012 N A soap film has two free surface, so total force on the slider due to surface tension is `F = 2 (Sxxl ) or S = (F)/(2l) = (0.012)/(2xx0.10)`
` = 0.06 Nm^(-1)`