A U-shaped wire is dipped in a soap solution, and removed. The thin soap film formed between the wire and the light slider supports a weight of `1.5xx10^(-2)N` (which includes the small weight of the slider). The length of the slider is 30 cm. What is the surface tension of the film?

Answer

`25 xx 10^(-2) Nm^(-1)`

Explanation

`sigma = mg // 2l = 1.5 xx 10^(-2) //2 xx 30 xx 10^(-2) = 2.5 xx 10^(-2) Nm^(-1)`