Exchange Definition and 262 Threads

The spin exchange operator would have the property $$\begin{align*}P\mid \chi_{\uparrow\downarrow} \rangle = \mid\chi_{\downarrow\uparrow} \rangle & &P\mid \chi_{\downarrow\uparrow} \rangle =\mid \chi_{\uparrow\downarrow} \rangle \end{align*}$$ This also implies ##P\mid \chi_{\text{sym.}}...

Homework Statement In an adiabatic container are placed , in rapid succession , a mass of ice , ##m_I= 2 kg## , at temperature ##T_I = -10 ◦C## and a mass of water , ##m_W = 1 kg## , at the temperature ##T_W = + 20 ◦C## . Determine : a) the total mass of water present in the container at...

I just learned that there is a well established theoretical picture that explains the change of momentum associated with direction change during a diffraction event, in terms of quantized momentum transfer to the diffracting object. For example, https://en.wikipedia.org/wiki/Duane's_hypothesis...

Homework Statement In a D2O experiment, will any of the Hydrogens be exchanged for D? Homework EquationsThe Attempt at a Solution It appears that it has no OH or NH hydrogens which will exchange but it does Have a carbonyl group with alpha hydrogens so I don't know if they might be exchanged...

Homework Statement Multiply these row excahnge matrices in the order pq qp and p^2 p = [0 1 0] [1 0 0] [0 0 1] q= [0 0 1] [0 1 0] [1 0 0] Homework EquationsThe Attempt at a Solution I don't understand why the solution is [0 1 0] [0 0 1] [1 0 0] do you not multiply rows by columns? When i...

They say that the Rh+ve blood group baby if developing can stimulate an immune response in the mother (Rh-ve) but the first baby won't be affected, My question is actually when exactly the Rh antigen comes in contact with the mothers blood?

Everywhere I ready about HF or DFT the term exchange correlation functional comes up. I have a couple of fundamental questions about these: 1) Books say that the correlation energy is the difference between the exact energy (lets say we've found that somehow) and the hartree-fock energy and...

I am reading Bruce Cooperstein's book: Advanced Linear Algebra ... ... I am focused on Section 1.6 Bases and Finite-Dimensional Vector Spaces ... I need help with the proof of Theorem 1.16 ... Theorem 1.16 and its proof reads as follows: Question 1 In the second paragraph of above proof...

Hi, I'd like to know if anyone has any information on how someone is able to attend a university on exchange that is not partnered with their home university? I am from Australia and my university has ties with many universities, however, I want to potentially go on exchange in Germany to study...

I think it would be fun to exchange holiday cards with PF members. If you wish to participate just reply in this thread and other participating members can contact you personally to exchange mailing addresses. I'll try to participate as much as I can. ps. if you get a "sciencey" card you must...

I'm looking for ways that a K^{0}_{L} can generate a K^{+} and I'm aware that a so-called 'charge exchange' process can allow this. However, I can't access the well-cited publication that appears when googling, ("Kaon inelastic scattering and charge exchange on nuclei - Phys. Rev. C 19 1393 - CB...

I am wondering something about the tree amplitude for exchange of a spin J resonance-- the basic calculation that exhibits the famous regge behavior. I see that one way to do the calculation is simply to note that the 4-point function for spin J exchange amongst massless particles arises from an...

I've been working in manufacturing industry for ~1.5 years starting from an assistant to a technician. Currently I am also pursing my Masters degree and I have a good opportunity to study abroad for a semester. Afterwards I'm considering some internship opportunities abroad too. Is it okay for...

Does an exchange of two identifical particles (electrons) lead to a new microscopic state?

Hello, this is my first post. This question is related to my final thesis. I'm calculating the heat exchange area of a radiator through heat exchange equations: Q = U*A*LMTD I have as data Q, and LMTD (this one through trivial calculations) In order to calculate U, I need the coefficients...

If we had a solid object of 1 square meter surface area, its maximum rate of radiation would be that of a blackbody of the same surface area, correct? Now, if we had a cloud of ultrafine (<100nm) dust wherein the surface area of the *cloud* was 1 square meter, would it be similarly limited? Or...

I'm just totally jazzed. I just bought an 8" f/6 Orion Deep Space Explorer (Dobsonian). Yeah, it's an old scope, but from what I understand, the mirrors on the older scopes were made by Discovery. I hope that would include this scope. At any rate, it needs two things to get it to viewing status...

Protons are in very close proximity with each other in a nucleus. This means there is constant electromagnetic interaction, of which the exchange particle is a photon. What determines the wavelength of this exchange photon? How do they exist in the nucleus: constantly being emitted, or staying...

Homework Statement An ideal monatomic gas is contained in a cubic container of size ##L^3##. When ##L## is halved by reversibly applying pressure, the root mean square ##x##-component of the velocity is doubled. Show that no heat enters of leaves the system.Homework Equations ##dU = dQ -pdV##...

Hi, so my question is along the lines of the following: Since the strong and EM forces are mediated by massless exchange particles, due to Heisenbergs uncertainty principle these forces are long range. Well, ok. But the weak force is mediated by W and Z bosons which are massive hence they can...

Hi, I'll describe my problem more specific. I have a continuous flow of this polymer thread (polystyrene) at 465 °K (190°C sorry I'm metric) that needs cooling down. It passes trough a water bath which is kept at 310°K (35°C). Now i try to calculate the heat exchange into the water, to...

Homework Statement In a 30% efficient, -16°C fridge, how much electrical energy will be used up to lower the temperature of 250 mL of 75°C water? If the fridge is rated at 150 W, how long will this process take? Specific Heat Capacity of Water = 4200 J/Kg×K Specific Heat Capacity of Ice = 2000...

I have now seen it repeated multiple times that a particle (a fermion, perhaps?) moving in a condensate can exchange particles (bosons, most probably) "without effect" -- the version of this that I run into usually goes something like that the energy of the condensate does not change AT ALL...

Homework Statement While reading d and f block elements from my book I got this line: "The irregular trend in the first ionization enthalpy of the 3d metals can be accounted for considering that the removal of one electron alters the relative energies of 4s and 3d orbitals. So the unipositive...

Trying to derive two functions which are eigenfunctions of the hamiltonian of 2 identical and indistinguishable particles and also eigenfunctions of the 2-particle exchange operator P. Need some help with my workings I think.Have particle '1' and particle '2' in a hamiltonian given as...

Exchange Particles are to show the transfer of (for example) +/- charge to the other side so the charges balance. But I don't understand... Beta plus decay: p → n + e+ + νe. This is just an example, the Feynman diagram shows a W+ boson transferring the positive charge to the right hand side...

Hey, What type of enamel paints is suitable to paint the tube bundle in heat exchange so that it allows heat transfer (minimize heat loss in the paint)? heat conductivity is not usually mentioned in paints specifications. Thank you ..

As many of you know better than me, photons are the carriers of the electromagnetic force, so they exchange is necessary for example in order to keep an electron around a proton in a hydrogen atom. So how does this work exactly? What is this “exchange”? In the mentioned system, which one of the...

I am (slowly) learning thermodynamics. I find a lot of it puzzling and makes me formulate many conjetures; I hope any of you can help me with this one about heat exchange. Let's start with this system: There is a closed hose loop filled with water; its temperature gradient goes from cold to...

I really want to understand the answer to this question. Q: What is an exchange particle? A: A virtual particle that let's force act between particles in an interaction. This answer was given in my A-Level textbook but I can't for the life of me decode what it means. For example in beta minus...

There have been several other smaller companies doing this for a few years now. It looks like Walmart is getting into it big time. I checked and my $100 Home Depot card is worth $87 at Walmart. How can I resist a deal kike that...

Hello ! How does the inclusion of a fraction of the HF "exact exchange energies" in an hybrid functional (B3LYP for example) can degrade the quality of the results ? I mean that the results are worst than expected because of the HF exchange, but if we call it "exact" how is it possible ? Thank...

My challenge is to provide a low-tech (DIY) way to purify the glycerol produced from soapmaking or biodiesel production. Simple distillation is out because the boiling point for glycerol is above its smoke point. Vacuum distillation and electrolysis do not count as low-tech. :) The input...

In case it's relevant, the context of my question is finding the allowed states of an atom. For example, given a nitrogen atom with (1s)2(2s)22p3, how do we find the possible states in terms of total orbital angular momentum L, total spin S, and total angular momentum J = L + S. It seems that...

Short version: If I have an insulated container(box) of some specific size. The inside temperature is temperature X. Ambient temperature is Y. Also X < Y. The box starts warming up. I log the inside temperature over time with data points. How can I determine one or more of the following based...

Homework Statement If an exchange particle held the moon together, what would the mass of the exchange particle be? Moon radius = 1737 km Homework Equations Well, I know that the range of an exchange particle is as follows: R=\frac{\hbar}{2mc} where m is the mass of the exchange particle and c...

When you add two angular momentum states together, you get states which have exchange symmetry i.e. the highest total angular momentum states (L = l1 + l2) will be symmetric under the interchange of the two particles, (L = l1 + l2 - 1) would be anti-symmetric...and the symmetry under exchange...

Consider the feynman diagramms for two freely propagating particles...Correction from one graviton exchange. Correction from two graviton exchange.The problem at hand is the divergence (of the math) at arbitary energys and each additional graviton exchange. So there are several resoultions and...

Homework Statement An aluminum vessel of 500 gr contains 117.5 gr water at 200C. a piece of iron of mass 200 gr and 750C is thrown inside. what's the final temperature and the water equivalent of the vessel. Homework Equations Specific heat of aluminum: 0.217 Specific heat of iron: 0.113 The...

hello to every on i m trying to desalinate seawater with an ion exchange membrane. the initial voltage of my simulation is 5 volt and it increase to 7 and 9Volt when i insert that data to Comsol it doesn't work and give the below error...

Hi, I'm studying engineering physics in Europe (3rd year currently). I'll be studying in a foreign country next year, but I am unsure as to where I should go. I have good enough academics to get into MIT (and probably the other ivy leagues), but I'm not from a well-off financial background...

Hey guys, newbie here and first post. I've got a (hopefully) simple question, but for some reason my brain just isn't working. I'm too used to working with metric, and even though it should be fairly simple, working with imperial units just hurts. Anyway, here's the problem: I have a specific...

Above is Figure 65 from Feynman's book QED. It shows the bidirectional stream of photons between an electron and a nucleus, that Feynman says "keeps the electron within a certain range." I can visualize repulsive forces, but I'm having trouble with attractive forces. I understand that force...

Edit: I've realized that it's not called a 'jacketed pipe', but simply a double pipe heat exchanger. Apologies, English is not my first language. I have been asked to scour the webs for information about how to calculate the heat exchange in a jacketed stainless steel pipe, with hot water in...

Hey, I just need to gather my thoughts and I would be happy for some feedback. I am an math student attending Norwegian University of Techology the moment, and will start my second year in autumn. I have started consider being an international student on my third year at University of...

I have a heat exchanger for a boiler flue. The flue is connected to two big (150 HP) boilers. A boiler HP = 33,000 BTUH. The are less than 80% efficient. The heat exchanger problem is this: The Flue contains gas temps above 300 F. The CFM is problematic but apparently the actual CFM could...

When an ideal gas expands in a piston during an isothermal process, does it necessarily absorbs heat from the surroundings in order to maintain its temperature? (Piston is not insulated). IF yes, When the same procedure is carried out in a perfectly insulated piston, then temperature drops...

Homework Statement Part (a): Find eigenvalues of X, show general relation of X and show X commutes with KE. Part (b): Give conditions on V1, V2 and VI for X to commute with them. Part (c): Write symmetric and antisymmetric wavefunctions. Find energies JD and JE. Part (d): How are...

Homework Statement Consider a system of two spin 1/2 particles, labeled 1 and 2. The Pauli spin matrices associated with each particle may then be written as \vec{\hat{\sigma _{1}}} , \vec{\hat{\sigma _{2}}} a)Prove that the operator \hat{A]}\equiv \vec{\hat{\sigma _{1}}}\cdot...

As far as I know identical fermions are antisymmetric under exchange. Identical bosons are symmetric under exchange. Is this fact blurred when we consider isospin? Considering the wavefunction of a proton-neutron system; \psi = \psi_{space} \psi_{spin} \psi_{isospin} I'm told this needs...