A square wire frame of each side $L$ is dipped in soap solution. On taking out, a membrane is formed. If the…
A square wire frame of each side $L$ is dipped in soap solution. On taking out, a membrane is formed. If the surface tension of solution is $T$, the force acting on the frame will be
$8 T L$
$10 T L$
$2 T L$
$54 T L$
Solution
The perimeter of square is $4 L$. So, including both sides, the total length will be $8 L$.
If $T$ is surface tension (force per unit length) then the total force will be $8 T L$
.