Question

The surface tension of a liquid is 5 N/m. If a thin film of the area 0.02 m² is formed on a loop, then its surface energy will be 

(A) 5 × 10^–2 J 

(B) 2.5 × 10^–2 J 

(C) 2 × 10^–1 J 

(D) 5 × 10^–1 J

Answer 1

Correct option: (C) 2 × 10^–1 J         

Explanation:

Effective area = 2 × 0.02 m² = 0.04m² 

Surface energy = surface Tension × effective area

= 5 × 0.04

= 0.2 J

= 2 × 10^–1 J