Wikipedia:Reference desk/Archives/Science/2016 July 1

= July 1 =

Bubbles
One thing that's always puzzled me: where does the "air" come from in the bubbles of boiling water? --2606:A000:4C0C:E200:1904:9CA2:35F0:1D79 (talk) 04:34, 1 July 2016 (UTC)


 * That would be steam.--Shantavira|feed me 05:30, 1 July 2016 (UTC)
 * Okay, steam contains air and water. How does the air component of steam get from the air/water contact surface to the bottom where the "steam bubbles" originate? --2606:A000:4C0C:E200:1904:9CA2:35F0:1D79 (talk) 05:43, 1 July 2016 (UTC)
 * Well the first words of steam are "Steam is water in the gas phase". The bubbles formed in boiling water are filled entirely with H2O.  Rojomoke (talk) 05:47, 1 July 2016 (UTC)
 * So when the heat energy converts the water molecules from one fundamental state of matter (liquid) to the next phase (gas), there is a "vast separation of the individual gas particles", locally increasing the volume X 1700, thus creating a void in the liquid seen as "bubbles". --2606:A000:4C0C:E200:1904:9CA2:35F0:1D79 (talk) 06:16, 1 July 2016 (UTC)
 * The gas content of the bubbles is Water vapor. AllBestFaith (talk) 14:24, 1 July 2016 (UTC)
 * Isn't water vapor the same thing as water in a gaseous state aka: "steam"? --2606:A000:4C0C:E200:1904:9CA2:35F0:1D79 (talk)  —Preceding undated comment added 15:38, 1 July 2016 (UTC)
 * The word "steam" is less precise because it is applied both to invisible water vapor and to the visible Mist of suspended droplets of condensed liquid. AllBestFaith (talk) 18:25, 1 July 2016 (UTC)
 * In addition, "steam" is only used for water vapor above the boiling point, as opposed to (for example) water vapor formed by evaporation from a mass of liquid that has entered the atmosphere as humidity." --69.159.60.163 (talk) 18:31, 1 July 2016 (UTC)


 * The bubbles in boiling water are indeed water vapour / steam, however as the water heats to boiling in a saucepan, bubbles form on the walls and they are filled with oxygen and nitrogen which were dissolved in the water as gas solubility decreases with temperature. This is one reason that boiled water that has been allowed to cool tastes different from unboiled water.  EdChem (talk) 15:46, 1 July 2016 (UTC)


 * Yes, although that will be a minor component, with most being water vapor. As for the use of the word "steam", in common use that does often mean a mixture of air and water vapor. StuRat (talk) 04:27, 2 July 2016 (UTC)


 * You can see the difference between there being a little air dissolved in the water when it first starts to boil and then later if it has boiled for a while that there is no air dissolved in the water anymore. In the latter case, if you have a big pan of water (say 4 liters or more), you can see that the boiling water contains a few very large bubbles, while in the former case you'll see many small bubbles. The temperature in the latter case is a bit higher, because with a little air in each bubble the vapor pressure needs to be slightly lower than atmospheric pressure for a bubble to be at atmospheric pressure. You can demonstrate that the temperature is indeed higher by turning the fire off. The few large bubbles will then disappear and we enter the window during which the temperature is higher for boiling with dissolved air but lower for boiling without dissolved air. If you now throw some rice in the water (the more the better), you'll bring quite a large number of air bubbles in the water, which will cause the water to boil explosively. Count Iblis (talk) 05:01, 2 July 2016 (UTC)

Isotop
What is the name for the isotopes of hydrogen and helium having atomic weight 3 ? — Preceding unsigned comment added by 36.253.255.101 (talk) 07:02, 1 July 2016 (UTC)
 * Tritium for hydrogen-3, no special name for helium-3. 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 08:03, 1 July 2016 (UTC)
 * There is "helion", although that's really a name for the nucleus itself (like "triton"), not the "isotope" (i.e., the species of atom) like "tritium". --Tardis (talk) 14:27, 1 July 2016 (UTC)

I have studied nuclear reactions, in the process of fusion there was written Tritium for both. — Preceding unsigned comment added by Achyut Prashad Paudel (talk • contribs) 04:58, 2 July 2016 (UTC)

Workplace politics in healthcare and academia
Do doctors and academics have to compete for career progression opportunities? I.e. Do they suffer from the same sort of politics you get in triangular structure organisations where the number of positions get less as you go higher up the organisational structure and so people "play the game" to go up. 2A02:C7D:B968:9D00:65A8:C88A:8471:56F0 (talk) 17:35, 1 July 2016 (UTC)


 * Can you name an organization that is not hierarchical? ←Baseball Bugs What's up, Doc? carrots→ 17:43, 1 July 2016 (UTC)


 * Let's see, there are organizations where the workers don't aim to move into management. Professional sports come to mind.  While a retired player might choose to become a coach, during their active playing years this seems like an unlikely choice.  Some teams have a captain, but that doesn't actually make them able to hire and fire people under them, so not really management.


 * Then there are organizations like food coops, which pride themselves on "Everyone being equal". Some churches do so as well, such as the Quakers. StuRat (talk) 17:33, 2 July 2016 (UTC)


 * List of anarchist organizations? --But isn't "anarchist organization" an oxymoron? --2606:A000:4C0C:E200:1904:9CA2:35F0:1D79 (talk) 19:14, 1 July 2016 (UTC)


 * Like "controlled spontaneity". ←Baseball Bugs What's up, Doc? carrots→ 23:21, 1 July 2016 (UTC)


 * Bear in mind that doctors sometimes maintain their own practices, and whether it's one doctor by himself, or a few doctors in partnership, there's no way to progress or regress, short of going out of practice entirely. It's not particularly different from a small business in that respect: you own it, so you can't go up from the top.  So no, not all doctors have to compete.  Nyttend (talk) 05:10, 2 July 2016 (UTC)


 * Academics have to publish or perish. AndrewWTaylor (talk) 12:14, 2 July 2016 (UTC)

DMM on a living person
I have been experimenting with my Digital multimeter tool on living people. (my co workers) I measure people's electrical resistance in ohms. Now when measuring resistance/continuity in an electrical circuit the power must be off. However my co workers are certainly alive so the measurements are taken with electrical fields going through their body. Most people measure 1 to 5 million ohms, others 30 million, while others have such high resistance the DMM reads "OL" (their resistance is higher than what the DMM can measure). Body mass seems to be an irrelevant factor, so my question is what determines a person's electrical resistance? 199.19.248.20 (talk) 22:27, 1 July 2016 (UTC)
 * It is mostly due to the surface of the skin and how moist it is. A sweaty skin will have lower resistance. Graeme Bartlett (talk) 23:11, 1 July 2016 (UTC)
 * Do you have a reference for that? 199.19.248.20 (talk) 23:13, 1 July 2016 (UTC)
 * You may find Electrodermal activity useful. ←Baseball Bugs What's up, Doc? carrots→ 23:19, 1 July 2016 (UTC)
 * I am tempted to answer body thetans, but that would be tragic. :) Wnt (talk) 00:33, 2 July 2016 (UTC)


 * You're asking for a copyright suit !! -- Q Chris (talk) 13:25, 4 July 2016 (UTC)
 * If you stick the probes through their skin into the bloodstream (same place and distance apart on each person), you will probably get more consistent results. Surface measurement is variable because of sweat, contact pressure contact area etc, etc. Try measuring across a persons tongue. That always gives good results.--BeamCollider (talk) 21:47, 5 July 2016 (UTC)