A rectangular film of liquid is extended from (4 cm × 2cm) to (5 cm × 4 cm). If the work done is 3 × 10 –4 J, the value of the surface tension of the liquid i
Text Solution
Verified by ExpertsThe correct answer is:
C
Increase in surface area = (20 cm 2 – 8 cm 2 ) × 2
= 12 × 2 cm 2
= 24 cm 2 (film has two surfaces)
So, work done = T. Δ S = T × 24 × 10 –4 = 3 × 10 ––4
so, T = 
= 0.125 N/m
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