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Liquid Helium II - The Superfluid

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who better than that of all the time and and all about 1 . 2 2 that In the you want to know if he has the right to you and to the fact that you have to do the government and the states and the EU and the beginning of the end of this year and in the U.S. and Japan in in a new town in the years you would be here in you you you you are in Europe and in the world of
work to have a lot of work redesignated transferred from the artist George came into our own experimented with here is a remarkable substance it has to be different and easily distinguishable liquid phases of warmer and colder water the warmer phases called liquid helium once and the cultivates liquid helium to the 2 phases are separated by a transition temperature known as the Land .period when liquid helium is cool down through the land of quite a transition from here and want to him to be clearly visible we will show it to later in this film that to immigrants behaves nothing like any other known liquids although it could be said that he didn't want the warmer approximates the behavior of commonly used helium the cold states which is truly different because of this it is called the superfluid the temperatures involved when working with the medium quite low helium boils at 4 . 2 with degrees Kelvin under conditions of atmospheric pressure and the land .period lies at roughly 2 . 2 I know that this corresponds to minus 269 and minus 271 degrees centigrade properties of liquid helium that have just been telling you about are characteristic of the heavy isotope of helium feel for the element in the form to stabilize tho told not until the 2nd and lighter ones helium-3 is very rare in abundance is only about 1 part of a 10 million pure liquid helium 3 is the subject of intensive study at the present time but so far no 2nd superfluid liquid phase has been found to exist for helium 3 below temperatures at which will be working call for well insulated containers the door meet our requirements the word during the scientific name given to a double wall wrestle with the space between the walls evacuate when these doors are made of glass the surface of this inner space is usually silver to cut down heat transfer by radiation however our jurors will have to be transparent so that we can look at what's going on inside now liquid helium is commonly stored in doubles the worst the design is quite simple just put 1 inside the other packed like this in the inner door with the liquid helium and in the space between the inner and outer during we maintain a supply of liquid air carriers that doubled work exactly like the 1 we will be using an hour demonstration experience the inner door is filled with liquid helium the arduous contains liquid air the normal
boiling temperature of liquid air is about 80 degrees Kelvin 75 or more degrees hotter than the liquid helium the purpose of the liquid there is twofold
1st we put the liquid air and the other 2 were well ahead of putting liquid helium in the work in this way the inner is pretty cool secondly we maintain a supply of liquid air in the other 2 were because it provides an additional mental
installations now that the liquid helium it's in the interest of the filing of the liquid air attest to the fact that it is absorbing some of the heat which ended the doubled to work even with the boiling of the liquid air the liquid helium is clearly visible later we will use liquid air cooled below its boiling temperature to reduce or eliminate the air bubbles for better visibility now the liquid air is cooled down and we have eliminated widening the smaller bubbles of the boiling liquid helium are clearly visible the cover over the
inner door has a poor at present open liquid helium is at atmospheric pressure sold its temperature is 4 . 2 with degrees Kelvin in other
words what we have in here now is liquid helium once the warmer of the 2 phases before we cool it down to take a look at the superfluid Phase I want to dwell briefly on the properties of even 1 I told you before they even and 1 is different from the normally with the distance between neighboring atoms in this liquid is quite large the atoms are not as closely packed as in the classical liquids the reason for this is quantum-mechanical the 0 . energy is relatively more important here than in any other liquid as a consequence liquid helium has a very low mass density only about 13 per cent of the density of water and a very low optical density the index of refraction is quite close to 1 that makes its surface hard to see with the naked eye under ordinary lighting conditions you are no doubt familiar with the fact that the helium atom has closed shell atomic structure this explains why the new-music chemically inert element it also accounts for the fact that the force of attraction between neighboring helium atoms the so-called vandals is small it takes little energy to fall to William Adams apart as for example in evaporation this gives liquid helium very small latent heat of vaporization only 5 calories are needed to evaporate 1 compare this with water where evaporation requires between 5 and 600 calories per gram the lowland evolves forced combined with a large 0 . Energy also account for the fact that liquid helium does not freeze cannot be solidified an ordinary pressures no matter how far cool however liquid helium has been solidified at high pressure liquid helium and
were is it 4 . 2 decree we don't want to cool it down to the London on ensuring the transition to the superfluid that will be cooling by evaporation using a vacuum now the land .period lies at 2 . 23 only 2 ingredients colder than the men temperature of the liquid was more not very much he has to be removed from the liquid helium known that you were estimated the land .period to only about 250 calories but nevertheless don't get the idea that this cooling process is easy on the contrary it's quite difficult more than 1 3rd of the liquid now and then do work has to be part of the way in the performance before we can get remain behind the land of that requires an awful lot of that explains why we we use this large and powerful vacuum pump over here
I even the best of the
cooling process takes a considerable amount of time
a if the Government and the
component and the 2nd on the team in the and we are invited to will
liquidity in the land .period I have already mentioned the liquid helium has a remarkably small newspaper nations only 5 calories per gram at the same time liquid helium at 4 . 2 degrees and the highest specific he told 1 gallery paragraph therefore 1 gram of paper on the way carries with it an amount of heat which can pull on the fibers and brands of liquid helium by 1 degree there's not very much cooling is less by a factor of almost 100 And when we cool water by evaporation the situation get even worse as cooling progresses below 4 . 2 degrees because this is the key to a liquid helium rises astonishingly as we approached 2 . 1 7 degrees the land the points leader liberalization on the other hand remains roughly the same so a given amount of paper carried off produces less and less schooling as we approach to .period 173 however monitor here is the low pressure gage connected to the space above the liquid helium the needle registers the pressure there is the saturated vapor pressure over the Greek EU the gages calibrated to the corresponding temperature we call it a vapor pressure from monitor as we approach 2
. 1 7 degrees boiling becomes increasingly violent suddenly stopped this was the transition the link you now see helium to even though evaporation does continue there is no boiling normal liquids such as the water in the speaker oil because of their relatively low heat conductivity before he had at 1 point can be carried away to a good place in the league with bottles of the day before
In 1 behave like a
normal liquid in this respect
the absence of more than a year to reveals that the acts as if it had a large heat conductivity as a matter of fact and the liquid helium passed through the land .period transition we just saw heat conductivity increased by the fact that the factor of 1 million the conductivity of helium to is many times greater than in the metals silver and copper which are among the best solid conductors and yet here we deal with liquid for this alone Gilliam to deserve the name of superfluid actually the way in which to transport such large quantities of heat so rapidly is totally different from the classical concerts for heat conduction come back to the subject later in connection with the experiment demonstrating the phenomenon of 2nd sound to remember that this great change in heat conductivity occurs at a single they've fixed transition temperature fell and the point we do the deal with the changing face only here is a change from 1 language to another liquid as we've told you before the specific heat of liquid helium is very large and the land .period in fact it became abnormally even below the lander .period involved again very rapidly with the temperature this discontinuity in specific he is another reflection of the fact that we're dealing with a change in the face of the substance by the way the current resembled the Greek letter lavender the transition temperature got its name from the shape of this we're in for more surprises the next 1 has to do with the viscosity of liquid helium when a normal liquid flow flows through a kill it will resist the flow in this experiment which cause some blistering to flow through it you move under its own weight the top layer is colored littering the liquid layer
closest to the 2 Wall adheres to its later next in from the 1 touching the wall close by it and retarded and loans due to the end of comic the land evolves force of attraction the 2nd layer turn drags on the 3rd and so on inward from the wall producing fewer distractions for viscosity
then there were that you this lower the lake with the rate of flow through it under a given head of pressure here I have a beaker with an underage ceramic bottom of ultrafine brought to many
capillary channels run through this surrounding this that diameter is quite small about 1 micron which is 110 thousand of cm there is liquid helium in the beacon is at 4 . 2 degrees Kelvin helium 1 the normal face the capillaries in the disk fine enough to prevent the liquid now the beaker from flowing through under its own weight clearly him 1 is biscuits To be sure it's viscosity is very small that's why we had to choose extremely fine capillaries to demonstrated here you see the
lender .period transition the union all for results the rate of pouring would not be noticeably slower if the porosity were made yet .period we call this kind of flow of super low the temperature
is now at 1 . 63 the flow is
even faster the viscosity of helium to in this experiment is so small that it has not been possible to find a value for it is less than the experimental uncertainty incurred in
attempt to measure and we now believe that helium to the superfluid has 0 viscosity although we should be more precise here we believe it's viscosity is 0 when observing capillary flow there's statement in mind we will come up with a contradiction to it in the next experiment where we will look for ways constantly by a different there is
a proper cylinder in the liquid helium so mounted that we can turn it on a vertical axis
In order to turn it smoothly and with as little vibration It's possible we think the cylinder into the armature of assembly induction mortar energized from outside to do work the 4 horizontal "quotation mark you see provided which turns the cylinder of liquid
helium is electrically not conducted the coils exert no talk of directly yet as we turn on our motor the liquid layer bounding the cylinder is dragged along by the boundary layer in turn right on the next play here and so on were
finally circulation shows up in the EU due to its own viscosity and the wooden paddle wheel is turned along what we have just seen or heard in helium what the normal rate at 4 . 2 degrees Kelvin that is to say this demonstration is consistent with our results for union won by capillary flow helium 1 in this case here you see the liquid cooled down and passing into the superfluid state he used to live turn on the motor we'll start again but this means 1st of all let me emphasize that like you know what you to is also known conducting in the electrical sector in other words the circulation in the experiment can only have been called to this because they're so we
conclude from the rotating cylinder observations that he enjoys biscuits and from the medical of capillary flow that has 0 discusses how experimentation has come up with a paradox no normal classical liquid is known to behave so inconsistently in capillary flow on the 1 hand and involve flow on the other this state of affairs forces us to think about him to the superfluid not as a single but conceptually when it appeared that the union had to separated and yet independent penetrating component maker which we shall call 1 component normal is this component which we hold responsible for the appearance of custody below the land points in the rotating cylinder experiment the normal component as the name suggests behaves like a normal liquid and therefore has Wisconsin is the 1 which the cylinders drags along
as it turned out that the normal complement cannot flow through the narrow channels of the ceramic this because of its
constitutes the 2nd component has 0 Wisconsin and it's called the superfluid ,comma whom we think that it does not participate at all in the rotating cylinder experiment in Overland Park it stated rests on the
other hand it control through channels of 1 micron diameter with the greatest of you encountering no
resistance whatever because it has no Wisconsin as we'll see later this flow is not impeded even when the capillary diameters army fired smaller than 1 might call this spot construction this called to Lewis models for quick to whether it is correct or not depends on further tests comparing the theory based on this model with experimental results we now go on to another phenomenon the fountain effect that you see here is a tool which narrows down and that opens into a a small piece of cotton this stuff that
construction between the 2 in the vault and above has been tightly packed with 1 of the finest part available to others through the 2nd quarter cotton keeps the powder in the vault this powder president extremely
fine capillary channel the average diameter is a small fraction of 1 might micron this device has been placed in the 2 the liquid helium is below the land upon we submerge the ball and then will
send a beam of light from this land to a point near the top you will see the light beam when the land is turned on it focuses some heat in the form of infrared radiation on the pointed questions the temperature will rise above the temperature of the rest of the apparatus that has turned it on liquid
helium flows through the hole in the bottom of the ball through the fine powder and rises above the level of the Criterium outside the height to which it will go depends on the temperature increase produced by the land focused on the ball we can very well where does the mechanical energy comes from that does the work necessary to prompt the liquid about the ambient levels before we attempt to discuss this question there are 2 other facts that should be noted the 1st this by obvious the upward flow through the bold must clearly be a superficial only the superfluid component of you too could get through the 2nd factor is more significant than me explaining this way the superfluid flow
spontaneously from a to B from a caller to a warmer place 28 years in the cold liquid but these being heated with infrared rays the 2nd law of thermodynamics positively says that he cannot by itself flow from a point of lowered to a point of higher temperature but does this mean to us here knowing as we do that the superfluid is flowing from a cold at warmer spot simply that it carries no heat no thermal energy any internal energy may still possess is no longer formerly available to say precisely it has 0 entropy we have discovered another remarkable property of you to it's superfluid component not only use friction-free it also contains no he said he'd energy contained in the medium to it's all resides all of that in the normal component we may cost and heat to the the superfluid component as we're doing when it passes a sparked heated by the man but in doing so we are converting it into the normal component that returned briefly to a question posed earlier mechanical work is done in pumping the liquid about equilibrium level where does it come from I cannot answer this question .period so that it survived it can you that we are dealing here with the heat In June the mechanical energy comes from that he added that the lights box an amusing demonstration of the franc-denominated again uses of bald packed with but this month opened into a capillary like he's been on the spot just below the capillaries and it produces a helium
fountain in I'm in this and the previous experiment has become known as the thermal mechanical or the fountain effect the land .period superfluid component of liquid helium creeps up along the walls of the container in an extremely thin until it is known as the Rollins this screening film is a variety of Super low it is difficult to make the film itself directly visible to you to show indirectly we've put some liquid helium into a glass vessels it is really land .period there is no corresponding this vessel the film rises along the inside wall and comes down along the outside collecting in rocks at the bottom the thickness of this creeping film is only a small fraction of 1 micron and on the order of 2 to 300 Engstrom its speed while small just below the land .period Mary a value as high as 35 centimeters protected at lower temperatures our next experiment deals with the phenomenon of sound we are all familiar with motion in inelastic materials the the solids liquids or gasses elastic energy of the formation carried away from a source in the form of we the characteristics of the speed of sound liquid helium is an elastic substance both above and below the land .period both you 1 to supports sound way now helium tool the superfluid state is also conducts heat in the form of way this remarkable property is shared by no other for better or for worse it has been called a 2nd time normally conduction is that the fusion process the rate of flow he is proportional to the temperature differences about the human toll is a process he told through Peruvian tool with a characteristic speed speed of 2nd sound we shall send small heat pulses into helium to from a heater they will spread away from the uniformly carrying the energy with them this is 2nd sound is small just a little over land acquired in the neighborhood of 1 . 6 degrees Kelvin it reaches a value of roughly 20 meters per 2nd and it is in this range that we will run our demonstration the experimental procedure is as follows there are 2 games In
the beginning year ,comma resistance with a and applied in layers on 1 side of each year in this way good thermal contact is established between the resistance and the beginning of a long resistant will be used as
the heater elected government will be sent through it impulses from this pulse generator by means of cable the here the output of the generator is also connected by a 2nd able to explore trade oscilloscope where it will be recorded on the voluntary in
other words it will require that he policy as it enters the liquid helium pulses have been turned off they themselves trigger the horizontal sweep of trades which recorded the time elapsed is calibrated at 1 millisecond per unit on the scale the pulses are 1 millisecond the pulses
leave the heater at the bottom in the form of 2nd sound and move up to where they strike the carbon resisted at the top being pulses the briefly raised its temperature carbon resisted is quite sensitive to changes in temperature and acts as a thermometer solve any of the
2nd sound creates a change in the resistance of the data year In hard to convert this week that involves and will all but we will do it to maintain a small current in the topic that is supplied from a battery in a metal
box Mark shields the circuit in order to reduce electronic nor in the voltage pulse is small in this 2nd box we have unamplified the end
violence but it's respect to the oscilloscope where it will appear other trace the horizontal planes on his face is exactly the same as for the bond rates however the outrage recordable this changes and the current the top resisted the director of 2nd the temperature of liquid is about 1 . 6 5 degrees Kelvin battery has been
turned on and now the amplifier among lawyers and other distortions in the upper create a clear-cut voltage pulse appears about 4 and a half unit to the right 4 and a half years seconds later than the polls entering the people pulse in the upper traces also about 1 million loss it is the 2nd sound as it arrived at the opposite of the arbitrator also shows stronghold of epilepsy simultaneous with the parts that you to pick up by electromagnetic waves with the ETA activists transmitter and the character as receiver detective stories that he hear the poll's moves with it to the letter noted that the echoes of 2nd sound which appeared on the arbitration while the detectors near the there caused by multiple reflections between the 2 resistance at all of 3 echoes is clearly visible leading the away from the increases the day here we have the resistance that the origin of this is they are 9 centimeters apart the wave of 2nd sound covers 9 centimeters in 4 and a half minutes at the speed of 2nd sound is 2 centimeters from MS for 2000 centimeters per 2nd for 20 meters per 2nd let me return to the discussion of the 2 would model for liquid helium to we find that it gives us an adequate quality description for the behavior of to the superfluid component is fraction-less and free of entropy is thought to be the part of his tool which leaks through the finest courses which rises up toward the source of heat in the fountain effect and which creates up along the walls of the container the normal component on the other hand is biscuits and processes some available he manages the normal component is thought to be that part of the U 2 which is dragged along by the rotating cylinder and which remained behind in the beaker the poorest bottom unless it is 1st converted to the superfluid company now come model alone is not a theory it turned out that quantum mechanics and had to be brought to bear on the problem of producing an accurate checks between theory and experiment as is usual when we attempt to explain quantum mechanical system by a classical models this model gets lost becomes washed out of the it's there but then again it is Molly's faults but many of the elements survived that's what has happened to the 2 fluid model for the week to him too must now be considered as a quantum mechanical system it is still true that he too is capable of 2 different types of motion but we cannot anymore claim that these 2 motions occur on different parts of the liquid water on different groups of EU map rather we should look at it all as 1 expert systems capable of 2 different types of emotions simultaneously the superfluid motion of perfect fluid flow reversible in the thermodynamic sense and the normal motion of this the laminar or turbulence and irreversible
Angeregtes Atom
Jahr
Stoff <Textilien>
Kaltumformen
Höhentief
Interstellares Gas
Proof <Graphische Technik>
Glasherstellung
Flugzeugträger
Isotop
Angeregtes Atom
Flüssigkeit
Nassdampfturbine
Umlaufzeit
Strahlung
Schwingungsphase
Atmosphäre
Sicherheitsbehälter
Intensitätsverteilung
Ersatzteil
Luftdruck
Bahnelement
Temperatur
Stunde
Theodolit
Blasenkammer
Flüssigkeit
Kaltumformen
Sichtweite
Atmosphäre
Einbandmaterial
Feile
Temperatur
Wärmequelle
Gasdichte
Optische Dichte
Höhentief
Licht
Längenmessung
Proof <Graphische Technik>
Urkilogramm
Druckkraft
Flüssigkeit
Nassdampfturbine
Schwingungsphase
Atomistik
Druckfeld
Atomhülle
Brechzahl
Luftdruck
Atombau
Bahnelement
Temperatur
Flüssigkeit
Umlaufzeit
Kaltumformen
Prozessleittechnik
Vakuumphysik
Ersatzteil
Vakuumpumpe
Leistungssteuerung
Theodolit
Temperatur
Prozessleittechnik
Steinmetz
Waffentechnik
Höhentief
Elektronisches Bauelement
Thermodynamische Temperaturskala
Proof <Graphische Technik>
Urkilogramm
Kugelblitz
Nadel
Monitorüberwachung
Flüssigkeit
Nassdampfturbine
Spezifisches Gewicht
Textilfaser
Druckfeld
Passfeder
Kühlturm
Wärmequelle
Papier
Temperatur
Wärmequelle
Nassdampfturbine
Höhentief
Besprechung/Interview
Proof <Graphische Technik>
Lautsprecher
Flasche
Rundstahlkette
Theodolit
Gewicht
Stoff <Textilien>
Schall
Drehen
Wärmekapazität
Temperatur
Mechanik
Thermodynamische Temperaturskala
Metallschicht
Förderleistung
Elektrischer Leiter
Flüssigkeit
Reflexionskoeffizient
Elektrolytische Leitfähigkeit
Fluidität
Jahr
Versilberung
Wärmequelle
Theodolit
Steckverbinder
Temperatur
Drehen
Druckfeld
Fluidität
Biegen
Zylinderkopf
Keramik <Technik>
Förderleistung
Druckkraft
Gewicht
Flüssigkeit
Scheibenbremse
Channeling
Drehen
Thermodynamische Temperaturskala
Fluidität
Besprechung/Interview
Proof <Graphische Technik>
Proof <Graphische Technik>
Kapillarität
Funkfeuer
Förderleistung
Theodolit
Temperatur
Fluidität
Kapillarität
Ankerwicklung
Flüssigkeit
Drehen
Motor
Granatwerfer
Selbstinduktion
Tesla-Transformator
Hohlzylinder
Modellbauer
Drehen
Elektronisches Bauelement
Zirkulator
Elektrizität
Proof <Graphische Technik>
Lenkrad
Förderleistung
Druckkraft
Übungsmunition
Angeregtes Atom
Flüssiges Helium
Flüssigkeit
Holz
Motor
Fluidität
Hohlzylinder
Raddampfer
Kapillarität
Flüssiges Helium
Modellbauer
Channeling
Elektronisches Bauelement
Aktives Bauelement
Fluidität
Hohlzylinder
Förderleistung
Computeranimation
Modellbauer
LUNA <Teilchenbeschleuniger>
Füllfederhalter
Förderleistung
Computeranimation
Werkzeug
Flüssiges Helium
A6M Zero-Sen
Aktives Bauelement
Modellbauer
Fluidität
Ersatzteil
Kapillarität
Buckelschweißen
Klangeffekt
Flüssigkeit
Kaltumformen
Kraft-Wärme-Kopplung
Channeling
Licht
Kugelblitz
Gauß-Bündel
Kopfstütze
Infrarot
Feuerwehrfahrzeug
Temperatur
Wärmequelle
Flüssigkeit
Schwarzes Loch
Kaltumformen
Kugelblitz
Elektronisches Bauelement
Biegen
Energieniveau
Förderleistung
Temperatur
Stoff <Textilien>
Modellbauer
Festkörper
Interstellares Gas
Hauptsatz der Thermodynamik 2
Energieniveau
Förderleistung
Computeranimation
Juni
Flüssiges Helium
Prozessleittechnik
Elektrolytische Leitfähigkeit
Kapazität
Aktives Bauelement
Biegen
Sicherheitsbehälter
Monat
Wasserfahrzeug
Klangeffekt
Schall
Kaltumformen
Füllfederhalter
Elektronisches Bauelement
Licht
Wärme
Glasherstellung
Proof <Graphische Technik>
Infrarot
Gas
Formationsflug
Angeregtes Atom
Werkzeug
Thermalisierung
Flüssigkeit
Kernfusion
A6M Zero-Sen
Jahr
Source <Elektronik>
Fluidität
Material
Kapillarität
Unterschallgeschwindigkeit
Temperatur
Wärmequelle
Explorer <Satellit>
Thermik
Jahr
Niederspannungskabel
Passat
Schaltelement
Generator
Buckelschweißen
Schall
Flüssigkeit
Kaltumformen
Kraft-Wärme-Kopplung
Direkte Messung
Maßstab <Messtechnik>
Biegen
Passat
Temperatur
Thermometer
Schall
Batterie
Metallschicht
Jahr
Spannungsänderung
Reihenschwingkreis
Buckelschweißen
Woche
Verzerrung <Elektrotechnik>
Schubumkehr
Potenzialausgleich
Drehen
Direkte Messung
Sensor
Laminare Strömung
Hobel
Bildqualität
Satz <Drucktechnik>
Minute
Förderleistung
Steckkarte
Woche
Echo <Ballonsatellit>
Atmosphärische Turbulenz
Rundfunkempfänger
Funksender
Biegen
Sicherheitsbehälter
Spannungsänderung
Bahnelement
Buckelschweißen
Klangeffekt
Schall
Füllfederhalter
Batterie
Elektronisches Bauelement
Gruppenlaufzeit
Tag
Proof <Graphische Technik>
Werkzeug
Flüssigkeit
Tonbandgerät
Reflexionskoeffizient
Mikrowelle
Elektromagnetische Welle
Jahr
Modellbauer
Ersatzteil
Hohlzylinder
Röhrenverstärker
Transparentpapier
Wärmequelle
Temperatur

Metadaten

Formale Metadaten

Titel Liquid Helium II - The Superfluid
Alternativer Titel Supraflüssiges Helium (Helium II)
Autor Leitner, Alfred
Lizenz CC-Namensnennung 3.0 Unported:
Sie dürfen das Werk bzw. den Inhalt zu jedem legalen Zweck nutzen, verändern und in unveränderter oder veränderter Form vervielfältigen, verbreiten und öffentlich zugänglich machen, sofern Sie den Namen des Autors/Rechteinhabers in der von ihm festgelegten Weise nennen.
DOI 10.5446/17736
IWF-Signatur W 658
Herausgeber Michigan State University
Erscheinungsjahr 1963
Sprache Englisch
Produzent Michigan State University

Technische Metadaten

IWF-Filmdaten Film, 16 mm, LT, 419 m ; F, 38 1/2 min

Inhaltliche Metadaten

Fachgebiet Physik, Technik
Abstract Experiment zur Demonstration der Eigenschaften von Helium II und Helium I. Versuchseinrichtung (Isoliergefäß), Verhalten am 2-Punkt (2,17 K), Wärmeleitfähigkeit und Viskosität, normale und superflüssige Komponente des Helium II, innere Reibung und Wärmetransport.
Demonstrates the elementary properties of the superfluid. Shows and discusses the lambda point of transition, a super leak, a bulk viscosity demonstration and a measurement of the speed of a second sound.
Schlagwörter Leitfähigkeit / Wärmeleitfähigkeit
flüssiges Helium
Wärmeleitung
Wärmeleitfähigkeit
Viskosität
Suprafluidität
Helium II
Helium, flüssiges
helium, liquid
helium II
superfluidity
viscosity
thermal conductivity
heat conduction
liquid helium
conductivity / heat conductivity

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