Q142 / 180 · COMEDK 2013 · Physics

A thread is tied slightly loose to a wire frame as shown in figure and the frame is dipped into a soap solution and taken out. The frame is completely covered with the film. When the portion $A$ is punctured with a pin, the thread
Figure

  • Correct answer
    A
    becomes concave towards $A$
  • B
    becomes convex towards $5 A$
  • C
    Either (a) or (b) depending on the size of $A$ with respect to $B$
  • D
    remains in the initial position

Solution

When portion $A$ is punctured, the soap solution comes out of the hole. So, due to surface tension, the solution in part $B$ tries to pull it toward itself. Thus, the thread becomes concave towards $A$.

Hence, the correct answer is option: 'A'.

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