Questions tagged [capillary-action]

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Why can't capillary tubes overflow due to this reason?

It is known that raises to a certain height based on the parameters of surface tension, the radius of the tube, etc. Given by the formula $$h=\frac{2S\cos \theta}{\rho Rg}$$ When the capillary tube is ...
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How does a capillary pressure drop affect evaporation?

Normally phase changes are said to occur at a constant pressure, but in situations with a capillary pressure drop (like a heat pipe as shown in the picture below) there is a difference in pressure ...
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Why do we consider only liquid-air surface forces in capillary rise?

Consider this diagram from wikipedia. Now the diagram clearly depicts forces due to three interfaces. But in the derivation of capillary rise, we only consider the force due to Surface Tension of the ...
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Free Body Diagram of Capillary Rise

I found have found several diagrams for capillary rise and they often display different forces. What is shown in one diagram may not be covered in the other. Can someone provide me with the free body ...
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30 views

Laplace pressure

I'm quite confused with Laplace pressure. I know the formula is (at least considering a spherical surface) $\Delta P = P_{in}-P_{out} = \frac{4\sigma}{d}$. What exactly is the surface you have to ...
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Smaller droplets == smaller surface tension?

When applying soap liquid on the inner surface of swim goggles, the surface tension of the water decreases and small droplets of water on the surface won't form, therefore the fog won't form. In this ...
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64 views

What would happen if two liquids of different nature are mixed together?

I was studying surface tension the other day and this thought came to my mind. What would happen if say a liquid like mercury which has higher cohesive forces than adhesive ones(hence the convex ...
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29 views

Capillary rise of water in a capillary tube

While I was selfstudying capillary rise I came to a point thinking how the meniscus in both ends of a water drop in a capillary tube would appear if it were falling under gravity then I built my ...
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28 views

Why does the liquid column in a capillary tube exert pressure as its weight is already balanced by surface tension?

I read that the meniscus, due to surface tension, exerts an upward pull to the liquid column below it. The water rises to a height until the weight balances the pull. Now liquid exerts pressure ...
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110 views

Measurement of Surface Tension of a Liquid by Capillary Rise Method [closed]

The surface tension at the point of contact for water is inwards (as written in my book) so that would mean it vertical component is downwards but why is that vertical component considered upwards? I ...
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56 views

Angle of contact in a capillary tube?

Why the angle of contact of water and glass is 0. According to the capillary action why the angle of contact of water and glass is 0.
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120 views

How can a tree fill a coconut with water? [duplicate]

Water goes up in plants by cappilary action. So that should also explain water inside coconuts. My doubt relates to the easy experiment of transfering water from a filled glass to an empty one using ...
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97 views

Why can water wicks act like siphons?

Take two empty cups (cup A and cup B) and fill cup A with water. Take a length of wet cloth and run it from the bottom of cup A to the bottom of cup B, while the cups are standing next to each other ...
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31 views

Mechanism behind capillary action

When we place a capillary tube in a beaker containing a liquid, why does the liquid level in the tube rise? Also, if it rises, won't there be a difference in the pressure at points A and B?( A is ...
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1k views

Pressure variation in a capillary tube

The following image shows capillary tubes placed in beakers containing water and mercury: We know that the rise or fall in the level of liquid in a capillary tube is given by Jurin's law: $$h=\frac{...
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1answer
132 views

Does capillary action affect the accuracy of mercury barometer?

We know that mercury barometers are used to measure the atmospheric pressure by determining the height of mercury in the vertical column. Further, we know that the level of mercury in a capillary tube ...
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106 views

Surface tension and Speed of capillary action

I have read that the height of meniscus in a capillary is directly proportionate to liquid-air surface tension. That left me wondering, is the speed at which capillary action occurs also ...
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2answers
47 views

How to avoid water tension in a hose?

I am doing a project in which I have to flow water between two containers, which are connected at the bottom by a 1/4" hose. Remarkably, the surface water tension is such that water does not flow ...
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1answer
153 views

Why does solder wick absorb solder?

Solder wick is basically just braided copper wire that absorbs molten tin solder in contact. But how does it work? The molten solder is very effectively sucked into the braids. The same effect is not ...
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954 views

How is it possible for tall trees to pull water to heights more than 10m?

Which force actually drives water so high up, since pure atmospheric pressure will only get you up to about 10 meters if you're using suction and a long straw and yet tallest trees are over 100 meters ...
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179 views

Capillary tube under atmospheric pressure

I found that capillary tubes in refrigeration system are tubes with very small diameter and very long length. Pressure drops down suddenly due to very small diameter of the capillary and length. The ...
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204 views

Diameter to prevent water flow into a closed-end tube?

Imagine I drill three holes of different diameter into a large block of plastic but the holes don't go all the way through. (They form three close-ended tubes, see the image.) I then submerge the ...
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104 views

Height of fluid and pressure

It’s a well known fact that pressure at bottom of the contain depends on height of the fluid column above it. If I add a ultra thin capillary tube as a fifth tube, then height of the water column ...
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1answer
89 views

Capillary action

I've learnt that capillary action is caused by forces acting on molecules near the interface between solids, liquids (and gasses as well). But there are few things I don't understand. Imagine we have ...
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Determining the height of water level rise in a combined capillary tube

What will happen when we fix another capillary tube upon a capillary tube which has not enough space to its free capillary elevation?
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906 views

Does capillary rise violate hydrostatic paradox?

If $p$ is a pressure and $p_A = p_{\text{atm}} + hdg,\,$ $p_B = p_{\text{atm}}$, is hydrostatic paradox violated, shouldn't $p_A=p_B$?
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144 views

Measure static pressure with measuring tubes of different diameter

Assume you have a horizontally placed cylindrical pipe with constant diameter. There is a flow of water, through this pipe. You want to measure the static pressure inside the tube, which should be the ...
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70 views

On inserting a thin capillary tube into a large tray of water, does the total surface energy and the total potential energy of the system increase?

In both cases, the system is the liquid in the (tray+tube). I have made reasonably accurate calculations for the gravitational potential energy part. It follows from the calculations that the ...
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72 views

Why does liquid rise to same level in these different capillaries?

I'm having a doubt in the two types of approaches used to calculate the liquid rise in capillaries- one by the excess pressure method and the other by balancing weight of fluid column by the forces ...
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1answer
533 views

How fast does liquid rise in a capillary tube?

Take a small diameter tube, stick it in water, and surface tension will drive the fluid up through the tube. How fast is the fluid moving through the tube during this process? Here's my attempt: ...
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67 views

Curvature of fluid surface next to a floating sphere

I want to estimate the curvature $\kappa$ of the fluid surface next to a floating sphere. The situation is static and shown here: The fluid density is $\rho$, downward gravity is $g$, sphere radius ...
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354 views

Capillary length and Bond number confusion

The Bond number represents the ratio of gravity forces to surface tension forces, and is defined as $$ Bo = \frac{\rho g L^2}{\sigma}$$ where $\rho$ is the fluid density, $g$ is gravitational ...
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63 views

Will water spill out of filled capillary tube, if raised from water?

if to raise a filled capillary tube from the level of water, will the inside will spill out? or will it keep stuck inside? imagine a capillary tube put in water, the water rises inside the capillary ...
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541 views

Laplace pressure of a capillary bridge

Laplace pressure is given by $$\Delta p=\gamma \left(\frac{1}{R}+\frac{1}{R'}\right)$$ where $R$ and $R'$ are the radii of the curvature of the surface. Using the following diagram the book I'm ...
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1answer
36 views

Capillary force to move a mobile glass rod

Visualise a glass rod bent to form three sides of a rectangle. A second rod, free to roll on the two parallel sides on the rectangle, constitutes a fourth side of length l. If the apparatus is dipped ...
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1answer
293 views

Why does a fountain pen soak ink automatically at times?

I've had a rather interesting fascination with fountain pens. The mechanism is a thing of beauty, but my attention was recently caught by a rather insignificant phenomenon which I've used a lot in my ...
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103 views

Why does water hold up between the teeth of my comb?

Image for reference: As can be seen in the above image, whenever my comb comes in contact with water, a little of it is trapped between the teeth. This happens whether I dip it in still water or ...
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458 views

Does molten solder flow towards a heat source?

When soldering both plumbing and wiring I have heard the advice that you shoulf apply solid solder opposite to your heat source, since the solder "will flow towards the heat" once it melts. Is this a ...
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1answer
80 views

The vertical component of surface tensions in wetting

To find the contact angle made by a droplet on a flat surface at equilibrium, we take the sum of all surface tensions at the boundary of the droplet to be equal to zero (Wikipedia link). Projecting ...
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1answer
271 views

How do honeycomb humidifier wicks soak up water?

I'm trying to figure out how I can make my own humidifier filter/wicks since all the commercial ones seem to be treated with antibacterial chemicals that I don't want to breathe. I thought I would be ...
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1answer
396 views

Is Pascal's law incorrect?

Consider the figure given below. Here I'm gonna talk about capillarity. The liquid inside the beaker as well as the column is water. As water has a tendency to rise in the capillary as shown, doesn't ...
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Can water drip from a capillary tube top? Perpetual motion?

In a normal capillary tube (ex: tube A), where the water doesn't travel as high as the tube's height, h, the meniscus formed is "normal" (concave, as seen in tube A). From previous posts, I ...
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Capillary Perpetual Motion

Can anyone figure out what is wrong with this perpetual motion machine? What part of it violates physics? I found it on a website a while ago, and I couldn't figure out what was wrong with it. Thanks, ...
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397 views

Capillary tube and mercury going up

My question is quite straight forward: What forces are pushing mercury up a capillary tube and then preventing it from going higher as tube gets thinner? Setup: We've got a container filled with ...
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378 views

Capillary action in different tube diameters with mercury

Imagine we put two glass tubes in a container bulged with mercury. These tubes have 2 radii which we call them : 1.Big 2.Small The height of mercury column in the big one is more than the small one. ...
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271 views

Water movement in variable diameter bent capillary?

So, I recently learned that if a capillary tube is bent in an upside down U shape, the meniscus formed will be convex (towards the ground). Furthermore, the height (shown as h) traveled by the water ...
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529 views

Meniscus in U-shaped capillary?

What does the meniscus look like for a U-shaped capillary? From similar questions, I learned that the total height (labeled as h) reached by the water in the un-bent capillary is less than the total ...
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Why is the critical seperation distance between two plates for capillary condenstation to occur negative?

I am currently reading this paper: Auto-adhesion model for MEMS surfaces taking into account the effect of surface roughness Can be found here: https://www.spiedigitallibrary.org/conference-...
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993 views

Doubt in capillary rise

The capillary action formula is given as: $$h=2T/ρgR$$ where h is the capillary rise, R is the radius of curvature of miniscus, ρ is density, g is force of gravity and T is the surface tension. Now ...
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262 views

Concept of contact angle, cohesive and adhesive forces

I was reading the topic of contact angle from a book and I couldn't exactly understand it. The first photo depicts the general case when a solid surface touches a liquid surface. $Fs$ is the adhesive ...