Capillary rise a phenomenon that is attributed to the following property of fluid:
Try it first: pick an option, then read the explanation.
Correct answer: B. surface tension
Asked in SSC JE 2014, EVENING
Detailed Explanation
The elevation of a liquid in a narrow bore tube against gravity is driven by interfacial energy at the curved meniscus.
Why “surface tension” Is Correct
Capillary rise is driven by surface tension, which generates a vertical tensile force component around the tube perimeter that supports the liquid column.
Why the Other Options Are Wrong
- A. density: Density determines the weight of the column and limits the height, but does not drive the rise.
- C. vapour pressure: Vapour pressure governs cavitation and boiling, not capillarity.
- D. viscosity: Viscosity governs the rate of rise, but does not determine the static capillary phenomenon.
Key Point
Capillary rise is attributed directly to surface tension.
Key Concepts for Students
- Equilibrium height h = 4T cosθ / (ρgd).
- Vertical upward surface tension force: F_T = π d T cos θ.
- Gravity downward force: W = (π d² / 4) h ρ g.
Practice more: this is question 73 in Properties of Fluid MCQs – Part 5. Try the whole set and check every answer instantly.