The work done in increasing the size of a soap film for 10cm × 6cm to 10cm × 11cm is 3 × 10-4 J. The surface tension of the film is
1.0 × 10-2 N/m
6.0 × 10-2 N/m
3.0 × 10-2 N/m
1.5 × 10-2 N/m
C.
3.0 × 10-2 N/m
Given:-
Increasing size ΔA = (10 × 10-2 × 11 × 10-2 - 10 × 10-2 × 6 × 10-2 )
ΔA = ( 10 × 11 - 10 × 6 )
Work done = area increased × surface tension
surface tension
ST =
(since soap film has two surfaces)
ST = 3 × 10-2 N/m