Question

a thin wire is bent in form a ring of diameter 3 cm in this place was only on the surface of soap solution and then Raise Up slowly how much a word force is Nestle to break a vertical film formed between ring and the solution

Answer 1

Given, d = diameter of the ring of wire = 3 cm = 0.03 m.

Therefore r = radius of ring of wire = diameter/2 = d/2 = 0.03/2 = 0.015 m.

We know, k = surface tension of soap solution = 0.05 N/m, L = length of ring = circumference of circle = 2πr = 2 (3.14) (0.015) = 0.0942 m.

Then the upward force is given as F = 2 k L. If we insert the values in the equation, we get F = 2(0.05) (0.0942). Hence F = 9.42 x 10⁻³ N.