A soap film is formed in a rectangular frame of length ` 7 xx 10^(-2)` m when it is dipped in soap solution. A weight of `0.4 xx 10^(-3)` kg is required to pull the frame . Surface tension of the soap solution is

Options

A. `2.8 xx 10^(-2)` N/m
B. `0.27xx10^(-2)`N/m
C. `27xx10^(-2)`N/m
D. `270 xx10^(-2)`N/m

Answer

A

Explanation

`T = F/(2l) = (0.4 xx 10^(-3) xx 10)/(2xx 7xx10^(-2)) = 2.8 xx 10^(-2)` N/m