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MHT CET · Physics · Mechanical Properties of Fluids

A frame made of metallic wire enclosing a surface area \(A\) is covered with a soap film. If the area of the frame of metallic wire is reduced by \(50 \%\), the energy of the soap film will be changed by

  1. A \(100 \%\)
  2. B \(75 \%\)
  3. C \(50 \%\)
  4. D \(25 \%\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(50 \%\)

Step-by-step Solution

Detailed explanation

Surface energy \(=\) surface tension \(\times\) surface area
\(
E=T \times 2 A
\)
New surface energy,
\(
E_{1}=T \times 2\left(\frac{A}{2}\right)=T \times A
\)
\(\%\) decrease in surface energy
\(
\begin{array}{l}
=\frac{E-E_{1}}{E} \times 100 \\
=\frac{2 T A-T A}{2 T A} \times 100=50 \%
\end{array}
\)
From MHT CET
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