Question
Question: The surface tension of a liquid is 5 N/m. If a film is held on a ring of area 0.02 m<sup>2</sup>, it...
The surface tension of a liquid is 5 N/m. If a film is held on a ring of area 0.02 m2, its total surface energy is about –
A
5 × 10–2 J
B
2.5 × 10–2 J
C
2 × 10–1 J
D
3 × 10–1 J
Answer
2 × 10–1 J
Explanation
Solution
Because film has two surface so
DU = T × (2A) = 2 × 10–1 J