ExamBro
ExamBro
JEE Mains · Physics · STD 11 - Surface tension
  • JEE Mains 2020
  • Medium
  • Numerical

When a long glass capillary tube of radius \(0.015\;cm\) is dipped in a liquid, the liquid rises to a height of \(15\, cm\) within it. If the contact angle between the liquid and glass to clase to \(0^{\circ},\) the surface tension of the liquid, in \(milli\,Newton \;m ^{-1}\) is \(.....\) \(\left[\rho_{\text {(liquid) }}=900\; kg\,m ^{-3}, g =10\, ms ^{-2}\right]\) (Give answer in closest integer)

Pick an option to check your answer.
Verified Solution

Answer & Solution

Correct Answer

(C) \(101\)

Step-by-step Solution

Detailed explanation

Capillary rise

\(h =\frac{2 S \cos \theta}{\rho gr }\)

\(S=\frac{\rho grh}{2 \cos \theta}\)

\(=\frac{(900)(10)\left(15 \times 10^{-5}\right)\left(15 \times 10^{-2}\right)}{2}\)

\(S=1012.5 \times 10^{-4}\)

\(S=101.25 \times 10^{-3}=101.25 mN / m\)

In question closest integer is asked

so closest integer \(=101.00\)

From JEE Mains
Explore more questions on app