Name: capillary action in thin tubes
Uploaded: 2023-05-16T08:18:41.000Z
Duration: 1 min 18 s
Channel: JoVE

Capillary action is the ability of a liquid to flow against gravity in narrow spaces.
It occurs due to the combination of two opposing forces: cohesive forces, which cause the liquid to minimize the surface area and form a round shape, and adhesive forces, which cause the liquid to cling to the surface.
Consider capillary tubes in two different beakers. If the adhesive force is stronger, the liquid forms a concave meniscus. If the latter is stronger, the meniscus is convex.
This equation gives the relationship between the height of the liquid rise and various parameters.
The rise in height is independent of the capillary&#39;s shape but is inversely proportional to the capillary radius and the liquid density.
The rise or fall in a capillary tube also depends on the contact angle. The liquid rises if the contact angle is less than 90 degrees and falls if it is greater than 90 degrees.
Capillary action is essential for transporting water and nutrients in plants and applies to&#160; many industrial processes, such as dyeing and chromatography.

stijging van vloeistof in een capillaire buis

Wanneer zeer dunne cilindrische buizen, capillairen genaamd, in een vloeistof worden gedompeld, stijgt of daalt de vloeistof in de buis vergeleken met de omringende vloeistof. Dit fenomeen wordt capillaire werking genoemd. Capillaire werking vindt plaats als gevolg van de combinatie van twee tegengestelde krachten: de cohesiekrachten van de vloeistof, die ervoor zorgen dat deze aan zichzelf blijft kleven en een ronde vorm vormt, en de adhesiekrachten tussen de vloeistof en de wanden van de container, die ervoor zorgen dat de vloeistof aangetrokken te worden tot de containerwanden. Een voorbeeld van capillaire werking is te zien in water dat opstijgt in een smalle glazen buis. De cohesiekrachten van de watermoleculen zorgen ervoor dat het water een ronde vorm aan de bovenkant van de buis vormt in plaats van langs de zijkanten naar beneden te stromen. Een ander voorbeeld zien we bij planten, waar capillaire werking verantwoordelijk is voor het transport van water en voedingsstoffen van de wortels naar de verschillende delen van de plant. De smalle buisjes in de stengel van de plant, het xyleem genoemd, zijn afhankelijk van capillaire werking om water tegen de zwaartekracht in naar boven te bewegen. Capillaire werking speelt ook een rol in veel industriële processen, zoals het maken van papier, verven en chromatografie.

Stijging van vloeistof in een capillaire buis

When very thin cylindrical tubes, called capillaries, are dipped in a liquid, the liquid rises or falls in the tube compared to the surrounding liquid. ...

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Education

JoVE Core

Physics

Natuurkunde

Unit 1

Onderdeel 1

Fluid Mechanics

Stromingsleer

KEY TERMS AND CONCEPTS

BELANGRIJKE TERMEN EN CONCEPTEN

Rise of Liquid in a Capillary Tube

capillary action in thin tubes

Capillary action explains why liquid can rise or fall in a very thin tube compared with the liquid around it. A capillary is a narrow cylindrical tube, and the effect becomes noticeable when it is dipped into a liquid. The movement happens because two forces act in opposite directions.

Cohesive forces make liquid molecules stick to each other, so the liquid tends to hold together and form a rounded shape. Adhesive forces pull the liquid toward the walls of the container. In a narrow glass tube, water can rise because these forces work together in a small space.

The curved shape at the top of the water shows that the liquid is not flowing evenly down the sides of the tube. Capillary action also helps plants move water and nutrients from the roots to other parts of the plant. The xylem, which are the narrow tubes in a plant stem, use this effect to move water upward against gravity.

This process is important outside biology as well. It is used in industrial work such as papermaking, dyeing, and chromatography. These examples show that capillary action matters in both everyday liquids and specialized technologies.

Capillary Action in Thin Tubes

characteristics of fluids

Fluid Behavior Under Force

Fluid behavior under force differs from the behavior of solids. When a force acts parallel to the top surface of a solid, the solid resists it because of internal friction between its layers. This is called shearing resistance. If the force is removed, the shearing forces help the solid return to its original shape. Other deformation forces can also change the shape of a solid for a short time, as long as the force stays below a threshold magnitude. Solids usually keep their shape, which makes...

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density

Density, Floating, and Specific Gravity

Density helps explain why objects sink or float in a fluid. It is also useful for identifying a substance and for learning about its phase and substructure. The SI unit of density is kg/m3, and the cgs unit is g/cm3. Liquids and solids usually have densities that are roughly comparable. That matches the fact that their atoms are in close contact. Gases have much lower densities than liquids and solids because their atoms are separated by large amounts of empty space. Density does not always...

pressure of fluids

Fluid Pressure in Everyday Life

Fluid pressure appears in many everyday situations, including blood pressure and weather systems. The same force can have a very different effect depending on the area it acts on. A force spread over 1 mm² creates 100 times more pressure than the same force spread over 1 cm². That is why a sharp needle can pierce skin with a small force, while the same force from a finger usually does not. Pressure is especially important when studying fluids. A fluid does not offer much resistance to a force...

variation of atmospheric pressure

Atmospheric Pressure and Altitude

Atmospheric pressure and altitude are closely linked. As height increases, atmospheric pressure decreases. This happens because the gravitational force per unit area becomes smaller as we move away from Earth’s surface. To describe this change, the atmosphere is treated with a constant air temperature at a given altitude. The ideal gas law of thermodynamics is also used as a good approximation for the air. Let p(y) be the atmospheric pressure at height y. The density ρ at y, the temperature T...

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pascal's law

Pascal’s Principle in Static Fluids

Pascal’s principle explains how pressure changes move through a fluid that is not flowing. A fluid at rest is in static equilibrium. If the fluid is water, it is in hydrostatic equilibrium. In this state, the net force on any part of the fluid must be zero, or the fluid will begin to flow. Blaise Pascal described this idea in 1653 in Treatise on the Equilibrium of Liquids. He showed that when pressure changes in an enclosed fluid, that change is transmitted without loss through the fluid and...

application of pascal's law

Hydraulic Force Transfer with Pascal's Law

Hydraulic force transfer uses Pascal's law to move pressure through an enclosed fluid. Pascal showed experimentally that a change in pressure applied to a confined fluid is transmitted undiminished throughout the fluid and to the walls of its container. That idea is the basis of hydraulics, a major part of modern mechanical technology. Hydraulic systems appear in automotive brakes, hydraulic jacks, and many other machines. A simple hydraulic system uses two pistons at the same height. Because...

pressure gauges

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archimedes' principle

Buoyant Force from Fluid Pressure

Archimedes' principle explains buoyant force in a fluid. An upward buoyant force acts on an object that is partially or fully immersed in a fluid. This force is equal to the weight of the fluid displaced by the object. To see why an object floats, imagine removing a submerged object from the fluid. The space it occupied would be filled by fluid with weight w_fl. That weight is supported by the surrounding fluid, so the buoyant force must match the weight of the displaced fluid. The principle...

density and archimedes' principle

How Buoyancy Depends on Density

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accelerating fluids

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surface tension and surface energy

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buoyancy

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excess pressure inside a drop and a bubble

excess-pressure-inside-a-drop-and-a-bubble

Surface Tension in Drops and Bubbles

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contact angle

Wetting and Surface Curvature

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rise of liquid in a capillary tube

Capillary action explains why liquid can rise or fall in a very thin tube compared with the liquid around it. A capillary is a narrow cylindrical tube, and the effect becomes noticeable when it is dipped into a liquid. The movement happens because two forces act in opposite directions. Cohesive forces make liquid molecules stick to each other, so the liquid tends to hold together and form a rounded shape. Adhesive forces pull the liquid toward the walls of the container. In a narrow glass...

laminar and turbulent flow

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bernoulli's equation

Fluid Pressure and Speed in Motion

Bernoulli's equation connects fluid pressure with fluid speed. It helps explain why moving fluids can create pressure changes in everyday situations. One example is when two trains pass each other quickly and seem to pull inward. The same effect can happen when two cars pass each other at high speed. As the air between the trains or cars speeds up, its pressure drops. The air on the outside stays at atmospheric pressure. That pressure difference creates a net inward force on the vehicles.

bernoulli's principle

Fluid Pressure and Speed Changes

Bernoulli's equation links fluid pressure and fluid speed in a static, incompressible fluid. For horizontal flow, where gravitational energy density stays constant, the equation is especially useful. In that setting, the result is known as Bernoulli's principle. Bernoulli's principle says that fluid pressure drops when speed increases, and pressure rises when speed decreases. This pressure-speed relationship helps explain how moving fluids behave in simple flow situations. It also provides a...

bernoulli's principle: applications

Bernoulli's Principle in Fluid Devices

Bernoulli's principle helps explain how many fluid devices work when the fluid moves at a constant height. It is useful for devices that use fast flow to create low pressure and for devices that measure fluid speed. Some devices use this pressure change to pull one fluid into another. These are called entrainment devices. A Bunsen burner uses an adjustable gas nozzle to entrain air for proper combustion. An atomizer uses a squeeze bulb to make a jet of air that pulls perfume drops into the...

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energy conservation and bernoulli's equation

energy-conservation-and-bernoulli-s-equation

Bernoulli’s Equation in Streamlined Flow

Bernoulli’s equation describes energy in a moving fluid. It comes from the conservation of energy principle, or the work-energy theorem, applied to an incompressible, inviscid fluid in laminar, steady, irrotational flow. The equation says that pressure energy, potential energy, and kinetic energy per unit volume stay constant along a streamline. Each term has the units of energy per unit volume. The kinetic energy per unit volume is called kinetic energy density, and the potential energy per...

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viscosity

Viscosity and How Fluids Flow

Viscosity describes how easily a fluid flows. Water moves quickly, while honey and maple syrup flow slowly and stick to a surface. That difference comes from fluid friction between liquid layers and between a fluid and the material around it. In this example, water has a lower viscosity than honey and maple syrup. Viscosity is measured in newton-second per meter squared (N·s/m2) or pascal-second (Pa·s). It also changes with temperature and can differ from one fluid to another by several orders...

poiseuille's law and reynolds number

Fluid Resistance, Viscosity, and Flow Regime

Fluid resistance, viscosity, and flow regime shape how liquid moves through a horizontal tube. Fluid flows from high pressure to low pressure. The flow rate, Q, is the ratio of the pressure difference to the resistance in the tube. A larger pressure difference gives a higher flow rate. Poiseuille's law describes laminar flow of an incompressible fluid in a tube. In this relation, the factors that affect flow rate except pressure are grouped into resistance. Resistance depends on the tube size...

stokes' law

Terminal Velocity in a Viscous Fluid

Viscous forces act like friction in a liquid. They resist the relative motion of molecules and pull back on a solid body moving through the fluid. The size of this force depends on the body’s shape and size, its speed, and the liquid’s viscosity, density, and temperature. For a spherical solid object, the force in a fluid is described by Stokes’ law. This law applies only at low Reynolds number, when the flow is laminar and not turbulent. Experiments show that the force is proportional to the...

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key terms and concepts

Learn how capillary action makes liquid rise or fall in narrow tubes, why cohesion and adhesion matter, and how plants use xylem to move water.

Capillary Action in Thin Tubes | JoVE K12

physics

JoVE Core Physics introduces the theory and application of fundamental physics topics, including kinematics, dynamics, fluid mechanics, statics, waves, and acoustics, with concise and easy-to-understand animated videos. Additionally, the scientist-in-action videos demonstrate the application of related concepts in classical and original research experiments performed in today's laboratories worldwide.

Capillary Action in Thin Tubes

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