Question

The maximum tensile stress of water in capillary tube is ___________

(a) Proportional to the diameter of tube

(b) Inversely proportional to height of capillary rise

(c) Inversely proportional to the radius of meniscus

(d) All of the mentioned

I got this question in quiz.

I'd like to ask this question from Capillary Tension, Capillary Potential and Soil Suction topic in chapter Soil Water Effective and Neutral Stresses of Geotechnical Engineering I

Answer 1

The maximum tensile stress of water in capillary tube is inversely proportional to the radius of meniscus. The correct answer is (c) Inversely proportional to the radius of meniscus.

This is based on the Young-Laplace equation which governs capillary phenomena. The tensile stress (capillary tension) in a capillary tube is determined by surface tension and the radius of curvature of the meniscus. A smaller radius of meniscus results in higher tensile stress, demonstrating the inverse proportional relationship.

Key points:

- The capillary tension acts at the air-water interface

- It is caused by surface tension forces

- The radius of meniscus determines the magnitude of this tension

- This concept is crucial for understanding soil water movement and capillary rise