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

Options

A. becomes concave towards A
B. become convex towards A
C. either (a) or (b) depending on the size of A with respect to B
D. remains in the initial position.

Answer

C

Explanation

Pressure inside a bubble is greater than the atmospheric pressure, P= 4TYR. If a hole is made in A, air will escape through A. The thread will be bent towards A making a convex line looking from A. From B towards A it is concave.