Question

A liquid soap film in the shape of a plane loop has an initial area $0.05m^2$ if its area is lowly doubled then the increase in its surface potential energy from its initial value will be (surface tension of liquid = $0.2N/m$)

• A. $5\times {10}^{-2}J$
• B. $2\times {10}^{-2}J$
• C. $3\times {10}^{-2}J$
• D. None of these

Answer 1

The correct option is B $2\times {10}^{-2}J$

Given,

initial area =$0.05m^2$

surface tension of liquid = $0.2N/m$

Increment in Potential energy $=T\ast \Delta A$
$=0.02\ast 2\ast 0.05=2\ast {10}^{-2}J$