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What is the surface tension of a liquid, given the depression of the meniscus in a capillary tube dipped in the liquid is 0.03 \mathrm{~cm} ? The diameter of the capillary tube is 0.5 \mathrm{~mm}, the density of the liquid is 7.5 \times \frac{10^3 \mathrm{~kg}}{\mathrm{~m}^3}, the angle of contact of the liquid with the tube is 60^{\circ}, and the gravitational acceleration is 10 \frac{\mathrm{m}}{\mathrm{s}^2}.

Option: 1

0.38 \frac{\mathrm{N}}{\mathrm{m}}


Option: 2

5.625 \times 10^{-3} \frac{\mathrm{N}}{\mathrm{m}}


Option: 3

0.48 \frac{\mathrm{N}}{\mathrm{m}}


Option: 4

0.54 \frac{\mathrm{N}}{\mathrm{m}}


Answers (1)

best_answer

The surface tension of the liquid can be calculated using the expression:

T=\frac{\rho g d r}{2 \cos \theta}

Where T is the surface tension of the liquid, \rho is the density of the liquid, g is the acceleration due to gravity, \mathrm{d} is the depression of the meniscus in the capillary tube, \mathrm{r} is the radius of the capillary tube, and \theta is the angle of contact of the liquid with the tube.

Substituting the given values, we get:

T=\frac{7.5 \times 10^3 \times 10 \times 0.0003 \times 0.00025}{2 \times \cos 60^{\circ}}

T=5.625 \times 10^{-3} \frac{N}{m}

Therefore, the surface tension of the liquid is 0.42 \frac{\mathrm{N}}{\mathrm{m}} , and the correct answer is option B).

Posted by

Deependra Verma

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