Work of `3.0xx10^(-4)` Joule is required to be done in increasing the size of a soap film from `10cmxx6cm` to `10cmxx11cm`. The surface tension of the film is ……

Options

A. `5xx10^(-2)N//m`
B. `3xx10^(-2)N//m`
C. `1.5xx10^(-2)N//m`
D. `1.2xx10^(-2)N//m`

Answer

b

Explanation

Surface tension `T=("work")/("increase in area")`
As the soap film has two surfaces,
`thereforeT=(3.0xx10^(-4)J)/(2xx(10xx11-10xx6)xx10^(-4))`
`=3xx10^(-2)(N)/(m)`