Search any question & find its solution
Question:
Answered & Verified by Expert
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
Options:
Solution:
1112 Upvotes
Verified Answer
The correct answer is:
$50 \%$
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
$$
\begin{array}{l}
=\frac{E-E_{1}}{E} \times 100 \\
=\frac{2 T A-T A}{2 T A} \times 100=50 \%
\end{array}
$$
$$
E=T \times 2 A
$$
New surface energy,
$$
E_{1}=T \times 2\left(\frac{A}{2}\right)=T \times A
$$
$\%$ decrease in surface energy
$$
\begin{array}{l}
=\frac{E-E_{1}}{E} \times 100 \\
=\frac{2 T A-T A}{2 T A} \times 100=50 \%
\end{array}
$$
Looking for more such questions to practice?
Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.