Capillary Rise Quiz: Test Your Knowledge Of Liquid Motion

Concept: curvature–pressure link. A curved interface is associated with different pressures on each side. That pressure difference can support a column of liquid against gravity.

Concept: curvature strength. Tighter curvature means the interface is 'more bent,' so surface tension produces a larger pressure effect. This is why narrow tubes often show stronger capillary behaviour.

Concept: radius dependence. Smaller radius increases the influence of surface forces relative to weight. This generally produces a higher rise.

Concept: wetting and sign of effect. Poor wetting corresponds to a large contact angle and the opposite curvature. That can lead to the level being pushed downward instead of pulled up.

Concept: non-wetting example. Mercury’s cohesion dominates over adhesion to glass. The meniscus is convex and the level can be depressed.

Concept: wetting shape. Wetting pulls the liquid up along the walls. That raises the edges and creates a concave meniscus.

Concept: lower surface tension. Detergent lowers surface tension, weakening the capillary driving force. This typically reduces the maximum rise.

Concept: temperature effect. Lower temperature generally strengthens the cohesive effect at the surface. That increases surface tension and can strengthen capillary rise.

Concept: force balance. Surface tension provides an upward effect, while gravity pulls the liquid down. The final height is where these influences balance.

Concept: wetting controls sign. Whether the surface is concave or convex depends on wetting. That wetting behaviour determines whether the liquid climbs or depresses.

Concept: contact angle meaning. Large contact angles indicate the liquid prefers to stick to itself rather than the surface. That reduces wetting and often reduces capillary rise.

Concept: small-scale dominance. In tiny channels, surface forces can dominate over inertia and sometimes even over gravity. That makes capillarity a key design factor.

Concept: stronger surface tension. Higher surface tension strengthens the curvature-driven pressure difference. That can support a taller column against gravity.

Concept: wetting strength. Better wetting pulls the liquid along the walls more effectively. That supports a larger upward component of surface forces.

Concept: meniscus definition. A meniscus forms because surface tension and wetting shape the liquid surface near boundaries. Its curvature is linked to capillary pressure effects.

Concept: geometry effect. Wider tubes tend to have a larger radius of curvature for the surface. That usually means smaller pressure differences and weaker capillary rise.

Concept: pressure jump from curvature. Surface tension at a curved interface leads to different pressures on each side. This is central to why capillary rise occurs.

Concept: scaling. Smaller features increase the relative influence of surface forces. That’s why capillarity is a 'small-scale' phenomenon.

Concept: narrow + wetting. Thin tubes amplify curvature effects, and clean glass is wetting for water. Together, these conditions produce strong rise.

Concept: observable consequence. The rise height changes with tube size, temperature, and surfactants in consistent ways. This makes capillarity a practical way to study surface tension and wetting.