Question

A rectangular wire frame of size 2 cm x 2 cm, is dipped in a soap solution and taken out. A soap film is formed, if the size of the film is changed to 3 cm x 3 cm, calculate the work done in the process. The surface tension of soap film is 3 x10^-2 N/m

Answer 1

Answer: 3x10^-5 J or 30μJ 

Explaination:

A2=3x3=9 and A1= 2x2=4

Area are in cm² let convert it to m² 

A2=9x10^-4 and A1=4x10^-4 , T=3x10^-2

The expression for work done is,
 W=2T(A2−A1)   
=2×3x10^-2 x (9-4)×10⁻⁴     
=6x5x10^-6

=30x10^-6

=3x10^-5 J or 30μJ