Question

The formation of concave meniscus in capillary tubes takes place, only if ___________

(a) Inner tubes is dry

(b) Tube has non-uniform diameter

(c) Inner tube is wet

(d) Diameter of the tube is larger

The question was posed to me in unit test.

I'm obligated to ask this question of Capillary Water topic in chapter Soil Water Effective and Neutral Stresses of Geotechnical Engineering I

Answer 1

Correct choice is (c) Inner tube is wet

To elaborate: Concave meniscus will only take place if the inner walls of the tubes are initially wet. If the walls are dry, a depressed convex meniscus will be formed.