Question

A square frame of side L is dipped in a liquid. On taking out, a membrane is formed. If the surface tension of the liquid is T, the force acting on the frame will be

• A. 2 TL
• B. 4 TL
• C. 8 TL
• D. 10 TL

Answer 1

Answer: (C)

8 TL

Answer 2

Force on each side (due to two surfaces)

$\therefore$ Force on the frame = $4 ( 2 T L ) = 8 T L$