A rectangular film of liquid is extended from 4cmxx2cm"to" 5cmxx4cm If the work done is 3xx10^(-4)J , the value of the surfacetension of the liquid is …..

A rectangular film of liquid is extended from 4cmxx2cm"to" 5cmxx4cm If

1.	A rectangular film of liquid is extended from 4cmxx2cm"to" 5cmxx4cm If the work done is 3xx10^(-4)J , the value of the surfacetension of the liquid is …..
Answer» `0.2Nm^(-1)` `8.0Nm^(-1)` `0.250Nm^(-1)` `0.125Nm^(-1)` Solution :FILM has two free surfaces , `thereforeDeltaA=2[(5xx4)xx10^(-4)-(4xx2)xx10^(-4))]` `=2[20xx10^(-4)-8XX10^(-4)]` `=2xxx12xx10^(-4)` `=24xx10^(-4)m^(2)` `therefore` Work `W=2TDeltaA` `3xx10^(-4)=24xx10^(4)xxT` `thereforeT=(3xx10^(-4))/(24xx10^(-4))` `thereforeT=(1)/(8)` `thereforeT=0.125Nm^(-1)`