Question

write the Relation between the surface energy and surface tension​

Answer 1

$\huge\bf{\underline{\underline{Answer : -}}}$

Each arm of the frame experiences an inward force due to the film. Under the action of this force, the movable arm QR moves towards side PS so as to decrease the area of the film. If the length of QR is L, then this inward force F acting on it is given by

F = (T) × (2L)

Since the film has two surfaces, the upper surface and the lower surface, the total length over which surface tension acts on QR is 2L. Imagine an external force F′ (equal and opposite to F) applied isothermally (gradually and at constant temperature), to the arm QR, so that it pulls the arm away and tries to increase the surface area of the film. The arm QR moves to Q′R′ through a distance dx. Therefore, the work done against F, the force due to surface tension, is given by

dw = F′dx