Helium Definition and 389 Threads

Homework Statement Consider a star that consists entirely of helium. Make an estimate of the minimum mass for which such a star can ignite helium using the following assumptions: (i) helium ignites at a temperature of Tc = 10e8 K. (ii) assume that the critical mass can be determined by the...

Hello, I am a physics newbie (more of a computer scientist) but I was wondering, if a quart of liquid helium 4 had all of its electrons stripped from it and was super cooled, could it still reach the super fluid state? And once reaching that state would it retain a charge attraction? The...

At absolute zero, I understand that atoms have a minimum vibration (the atoms are not completely still). Because of this minimal vibration, He atoms can not freeze at absolute zero. But if enough pressure is applied, the liquid then becomes a solid. Does the pressure eliminate or reduce the...

Homework Statement An engineer is designing a system that requires transporting .01 m^3/s of helium at 15°C and 120 kPa. The velocity of the pipe is limited to 40 m/s. What size (diameter) of pipe is needed? My question is what equation do i need to solve this problem? Homework...

I have an exercise with the following text: Suppose you put both electrons in a helium atom into the n=2 state. What would the energy of the emitted electron be? I have attached the solution to the problem, but I am not sure I understand it. I understand the first part about the total...

Simple and stupid question! A Be atom is traveling with 60 kev kinetic energy and splits into two helium atoms, and the process itself releases 92.2 kev. One helium atom moves at a 30 degree angle with respect to x. find the direction of motion of the second helium atom and find the velocity...

I'm doing about wavefunctions for my course, I'm a bit confused as to why the wavefunction of Helium has 9 coordinates and time and not 6 coordinates and time. As far as I was aware the wave function was used to describe the movement of electrons around the nucleus of an atom, and it was assumed...

Part 1----------------------------------------- Ok, the site I have just read through is http://burro.astr.cwru.edu/stu/stars_lifedeath.html one. I have a few questions about it. Firstly, about the fusion of helium into hydrogen... http://burro.astr.cwru.edu/stu/media/fusion.jpg It...

Homework Statement A large research balloon containing 2000 m^3 of helium gas at 1.00 atm and a temperature of 15.0 celsius rises rapidly from ground level to an altitude at which the atmospheric pressure is only 0.900 atm (the figure (Figure 1) ). Assume the helium behaves like an ideal gas...

Pressure of Helium inside a balloon "floating" in air Homework Statement A spherical balloon of radius R = 2.98 m is made from a material of mass M = 3.16 kg and is filled with helium gas at temperature T = 285 K. Assume the thickness of the balloon is negligible compared to the radius of the...

So, when dealing with the Hydrogen molecule (H2) we know each electron is antisymmetric since they're fermions i.e. \Psi_\_ = 1/\sqrt(2) * (\Psi_a(r1) * \Psi_b(r2) - \Psi_b(r1) * \Psi_a(r2)) and then similarly for the spinor such that the total state, \Psi\chi is antisymmetric When you deal...

1. The problem statement. Calculate the energy generated per unit mass, if helium burning produces equal amounts (mass fractions) of carbon and oxygen. mH = 1.672621581 x 10^-27 kg 2. The attempt at a solution Helium burning produces carbon according to the following reaction: 3He -> C...

What prevents helium from becoming solid at normal atmospheric pressure? All other elements are solid at 0K, why does helium stay a superfluid liquid?

Helium has the only stable nucleus which does not absorb neutrons. At practical reactor conditions, say 300 atmosphere pressure and +300 Celsius temperature, how far would a fission spectrum neutron at say 5 MeV average, travel until it is thermalized? Under the same conditions, how far...

Homework Statement Helium gas is initially at a pressure of 16 atm, a volume of 1L, and a temperature of 600K. It is expanded isothermally until its volume is 4L and then compressed at constant pressure until its volume and temperature are such that an adiabatic compression will return the gas...

Hi folks. I had a strange thing happen to me and I was wondering if some of you physics gurus could explain it to me. It's my understanding that gas escaping from a pressurized tank makes things cooler. In fact I recently had to empty my scuba tanks for transport and the valves did indeed ice up...

Is helium miscible with O2, N2 or any of the other gases in air? If a container were filled with 95% helium and 5% O2, would the O2 gas settle to the very bottom of the container, leaving very pure helium gas at the top?

Homework Statement He+ ion consists of a nucleus which is an alpha particle plus one orbiting electron.Hence it has a net positive charge. a)Derive an expression for the electron state energies b)what is the wavelength associated with a transition between the lowest two energy states...

If you flip a scale upside down and hook it to the ceiling, then release a helium balloon under it, such that the balloon pushes up into the scale... A. What will the scale reading indicate? Will it really reflect the (negative?) weight of the balloon? B. Will the mechanics of how a scale...

Given the above quote reference Helium within our Heliosphere, I have a grouping of questions for the electromagnetic wise. If Earth and Jupiter were both placed within a dense Helium plasma region/field of our Heliosphere at the same time; and considering He plasma's high electrical...

For example, if I had contained helium, and then I increased the temperature and installed spinners and motors inside would that move due to the activity produced by the high energy helium , or would the movement caused by the helium not be powerful enough to move the spinners. (I think it...

I have having difficulty understanding why the ground state configuration of helium has a wavefunction that is the product of two hydrogenic 1s wavefunctions and the spin eigenstate of a singlet state. Firstly, why is the space wavefcn hydrogenic, and secondly, why is the spin wavefcn a...

When does helium fusion occur in an evolution of star? Well, i just need help in this confusing part of a star's life. First of all, when the sun finishes the H-fuel at core, why doesn't it immediatly use the H-fuel on the surface.. And then another doubt is, what causes the expansion of the...

Homework Statement How many helium-filled balloons would it take to lift a person? Assume the person has a mass of 76 kg and that each helium-filled balloon is spherical with a diameter of 33 cm. Homework Equations P = P0 + ρgV The Attempt at a Solution I really don't know why this is...

Homework Statement I have a tank that has 8000 cubic feet of helium in it. I have parts I'm filling to a gage pressure of 0.5 bar. The parts have a volume of 0.05ft^3. How many cubic feet of helium are in each part? Temperature is constant. Homework Equations I'm not sure if I'm missing...

Homework Statement It is known that the ionization temperature of hydrogen is T. Then, estimate the ionization temperature of the helium atom in terms of T. Assume that Bohr's theory is applicable, that is, All the electrons are occupying hydrogenic levels. By ionization temperature, we mean...

Homework Statement A helium atom has a rest mass of He = 4.002603u. When disassembled into its constituent particles (2 protons, 2 neutrons, 2 electrons), the well-separated individual particles have the following masses: p = 1.007276u, n= 1.008665u, e = 0.000549u. How much work is required...

Homework Statement a) Should liquid water at room temperature be treated as indistinguishable particles? b) Should liquid helium at 4 K be treated as indistinguishable particles? The attempt at a solution Composite particles made up of spin 1/2 particles such as atoms made up of...

I'm teaching periodic trends in a Gen. Chem. course, and it's commonly mentioned that the radius of an Li+ ion (90 pm) is smaller than that of the neutral Li atom (~160 pm), with the dominant reason being that the valence 2s1 electron was removed. The same trend shows up for the other alkali...

Hi, I'm just after a definitive answer on how Hydrogen fuses into Helium in the Sun? Some places say the Sun is so hot that they overcome their same charge repulsivness and fuse together while other places say that our sun is not hot enough for that to happen and that they just get close...

I've been looking at various papers which describe the mechanisms and provide calculations describing heat flow into helium. I'm trying to minimize helium loss and am in the market for a new dewar flask/cryostat. I plan on asking the supply companies directly what the proper dimensions are to...

Is there a way to reclaim the Helium that I put into a weather balloon? Meaning, I empty out a cylinder of Helium into a weather balloon, and for some reason I want to get it back into the tank (bad weather, missed launch time, MacGyver is on, etc.) and can't launch my balloon. Is there a way...

The total mass of helium in a balloon is 199 kg. What is the volume of the balloon? Enter only the numeric portion of the answer, not the units. That is the problem. I am having trouble locating a simple forumla for this. All I can seem to find involve having the radius of the balloon which...

Homework Statement The atomic site that is in thermal and diffusive equilibrium with a gas of Helium atoms that is on the surface of a metal can either absorb an atom of Helium or it can be vacant. (a) What is the Grand Partition function of the system? (b) Derive the average thermal...

Hi, Is it possible to control the attitude of helium balloons without cutting the balloons or dropping the weight? (e.g. using a remote control to control "something" to adjust the attitude) Thanks,

Homework Statement Adjacent wavelengths 251.1 nm and 238.6 nm are found in one series of transitions among the radiations emitted by ionized helium. 1.) Find the value of n0 for this series: Possible answers: n0= 1, 2, 3, 4, 5 2.) Find the series limit: Possible answers: λlimit= 91.13 nm...

Hi I am reading about transition in Helium, and I have come across a question. It is clear that triplet-singlet transition are not allowed, i.e. ΔS=0. But in my book (Foot's Atomic Physics) it says that Δl = ±1. This is what I don't understand. The selection rule Δl = ±1 we derived for...

Homework Statement Suppose we succeed in building a H-->He fusion reactor. How much hydrogen would have to be converted per second to supply the world's electricity consumption of 10^13kwh. Homework Equations This is what I am looking for, I think i can figure it out once I know the...

Just read this article and figured I'd share it: http://arstechnica.com/science/news/2012/01/size-matters-when-things-are-just-right-water-flows-freely.ars However I do have a question. The article never explained why helium, hydrogen, and other gasses were being blocked, they only explained...

Homework Statement Blimps are being considered for use as freight carriers. A scale model rises when filled with helium to a volume of 55.0 dm3. When 1.10 mol He is added to the blimp, the volume is 26.2 dm3. How many more grams of He must be added to make it rise? Assume constant T and P...

Homework Statement A helium balloon ride lifts up passengers in a basket. Assume the density of air is 1.28 kg1m-3 and the density of helium in the balloon is 0.18 kg1m-3. The radius of the balloon (when filled) is R = 5 m. The total mass of the empty balloon and basket is mb = 123 kg and the...

I'm trying to follow a derivation of the ground state energy of Helium using perturbation theory. I've made it through most of the derivation but I'm stuck at the following integral Homework Statement Find the value of C where C=\frac{1}{(4\pi)^2}\int...

Homework Statement Already it is on title ! Homework Equations attachents provide the most relevant equations i could find. The Attempt at a Solution I have found some old books written in 1920 decade ,dealing with this subject,but the solution they provide seems very hard...

Homework Statement g) A spherical balloon of radius R = 1.95 m is made from a material of mass M = 4.56 kg and is filled with helium gas at temperature T = 289 K. Assume the thickness of the balloon is negligible compared to the radius of the balloon, and the balloon just floats on air...

1. Homework Statement Question This is an experiment on a dilute isotopic mixture of helium gas. A spherical vessel of diameter 1 m is first filled with 4He gas to one atmosphere pressure. Then a small amount of 3He gas is introduced through a valve on one side of the vessel. Make a rough...

Hi all. Just got a question to ask, I'm slightly puzzled by it. Q. Say that you have a sealed container and you put in it 50% helium and 50% argon and you leave it for a few days. Because argon is heavier than helium, would the most of the helium rise to the top part of the container...

hi my question has to do with this energy level diagram http://upload.wikimedia.org/wikipedia/en/e/ed/Hene-2.png" i was wondering, what the meaning of this "fast radiative transition is"? as far as i understood this, the light that you mainly want to get is the transition from 3s to 2p. but...

Homework Statement The energy required to ionize a helium atom is 24.6 eV. If helium gas is bombarded with charged particles, at what incident energy will ionization of helium just be observed if the projectiles are (a) alpha particles (b) protons (c) electrons? Homework Equations Most...

I am trying to find the reason why a helium atom cannot be turned back into a hydrogen atom. We know in a star that through nucleosynthesis helium is formed from hydrogen and the process continues to form heavier elements. Is there a similar, but in reverse process where lighter elements are...

If you released a helium balloon and if it never popped how high would it rise?