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AP EAMCET · PHYSICS · Mechanical Properties of Fluids

A circular film of a liquid has an area of \(10 \mathrm{~cm}^2\). If the work done in making its radius two times the initial radius is \(8 \times 10^{-3} \mathrm{~J}\). the surface tension of the liquid is \(\left(1+\frac{1}{\alpha}\right) \mathrm{Nm}^{-1}\). The value of \(\alpha\) is

  1. A \(5\)
  2. B \(4\)
  3. C \(3\)
  4. D \(2\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(3\)

Step-by-step Solution

Detailed explanation

If radius ( \(r\) ) of a circle made two times (2r) \[ \begin{aligned} \text { then change in area } & =\pi(2 r)^2-\pi r^2 \\ & =3 \pi r^2=3 \times \text { initial area } \end{aligned} \] Here, initial area of soap film, \(A_1=10 \mathrm{~cm}^2\) Final area has a radius twice…