# Tag Info

1

As @JánLalinský nicely explains, surface tension is measured between two fluids, while viscosity is measured within one. Say that you have a droplet of some liquid this means that if you change the surrounding medium the liquid-surrounding surface tension changes, while the viscosity of the droplet will not. That said, if you keep the surrounding medium ...

4

Both viscosity and surface tension are connected theoretically to inter-molecular forces, but they are still very different concepts. Viscosity force is a force that acts only when the fluid is moving and acts to decrease the gradient of velocity in it. Viscosity is a characterization of the fluid itself. Roughly speaking, it says how fast momentum of ...

3

As is given in Jamie's answer I'll assume the surface is a revolution about $r=0$, that the mean curvature is proportional to the pressure difference, and that the radius of the cup is much larger than the inverse of this mean curvature. In this case the mean curvature can be specified as $$K_m = \frac{r''}{2(1+r'^2)^{\frac32}}$$ As in Jamie's answer the ...

0

In the formula for capillary rise only θ is a variable. So when the capillary tube of insufficient length is kept then the θ will change accordingly so that capillary length h comes out to be height of the capillary tube. Limiting case is when θ = 90 degrees when height of capillary tube is 0. This is meaningless so this is not possible. Concluding thing is ...

2

At the lower limit, if the bubble is very small the pressure inside will be so large that the gas inside can dissolve into the shell of the bubble, and from there diffuse out to the atmosphere. That limits the life time of small bubbles. On the large side, huge bubbles (several meters diameter) are certainly possible. These tend to be unstable because they ...

4

I don't know what you define as too large, but soap bubbles can reach very large sizes. https://www.youtube.com/watch?v=5bjggctu3kw It's a balance between the surface tension being weak enough to allow the film to stretch to large size but strong enough to not tear as it flexes. The soap added to water is for weakening the surface tension.

4

The height of the puddle I will use the common definition of puddle in the field of capillarity (which I believe you refer to) which is: a droplet on a flat horizontal surface flattened substantially by gravity as shown in the schematic below, coming from the book by De Gennes (2003). The droplet on the left is just a droplet (with contact angle ...

3

Rather than adding more cameras, just add some mirrors. The problem you have is that you are trying to do tomography with an under sampled system. This is a VERY broad subject - a bit outside of the scope of your question. But mirrors will work. I would recommend that you place them so the images are all in focus - depending on the depth of focus of your ...

4

You want to get the droplet to separate from the tip sooner than it otherwise would. I can think of some ways: blast it off with a puff of air. scrape it off with a hydrophobic knife-edge. increase gravity (centrifuge). eject no more liquid than you want, then transfer it to the desired surface (without forming a droplet). create a large drop, and then dry ...

Top 50 recent answers are included