A soap film in formed on a frame of area `4xx10^(-3)m^(2)`. If the area of the film in reduced to half, then the change in the potential energy of the film is (surface tension of soap solution`=40xx10^(-3)N//m)`

Options

A. `32xx10^(-5)J,16xx10^(-5)J`
B. `16xx10^(-5)J,8xx10^(-5)J`
C. `48xx10^(-5)J,12xx10^(-5)J`
D. `36xx10^(-5)J,2xx10^(-5)J`

Answer

A

Explanation

Potential energy of film `=2T.A`
`=2xx40xx10^(-3)xx4xx10^(-3)`
`=32xx10^(-5)J`
Change in potential energy
`2T.DeltaA`
`=2xx40xx10^(-3)[4xx10^(-3)-2xx10^(-3)]`
`=16xx10^(-5)J`