Exchange Definition and 262 Threads

Heat transfer is something I've been interested in since studying thermodynamics last semester, although during the course we never really covered anything much to do with what affected heat transfer. I can pretty easily understand that obviously having a higher surface area to exchange across...

how does the exchange coupling mechanism work that produce the ferromagnetic properties of materials?

Are exchange students, that are studying in the US for one year, allowed to enter the Putnam competition?

I(\vec{n}-\vec{m})=\frac{1}{N}\sum_{\vec{k}}I(\vec{k})e^{i\vec{k}(\vec{n}-\vec{m})} I(\vec{n}-\vec{m})=\frac{1}{\sqrt{N}}\sum_{\vec{k}}I(\vec{k})e^{i\vec{k}(\vec{n}-\vec{m})} In which cases is better to use first and in which second relation? N is number of knottes of lattice. And when I can...

Homework Statement You are given 2.5 102 g of coffee (same specific heat as water) at 70.0°C. In order to cool this to 60.0°C, how much ice (at 0.0°C) must be added? Neglect heat content of the cup and heat exchanges with the surroundings. Homework Equations Q=(m ice)(c ice)(delta T...

One of string theory's triumphs is the post-diction of a spin-2 field, which is supposed to represent gravity (GR). Yet, only in the weak field limit ("linearized") can it be shown that GR is a spin-2 field. So here's my question: why are string theorists confident that they have post-dicted...

What is it like to study engineering/technology in Japan? How about USA? I'm considering leaving Norway for a year of exchange, but I can't figure out where. I want to go to a good universiity without having to spend all my time studying.

Hello eveybody. I am attempting to solve a complex problem in a simple manner. I am not a physicist so stick with me lol. The Problem: The problem is based around determining the maximum force of a object colliding into a fence like structure. The object weighs 8kg and is...

Homework Statement The sun heats 2.00 x 10^2 kg of ammonia gas that is kept at constant volume in a large tank. Assuming that solar radiation of 6.00 x 10^2 W caused the heating, determine the length of time it took to raise the ammonia's temperature by 12°C. Homework Equations...

Homework Statement A block of steel dimension is 230mm*230mm*40mm=2,116,000cubic millimeters 0.00785 gram/cubic millimeters is the given steel density Using 180 degree celsius oil (density given is 0.9) to heat up the steel from 25 degree celsius to 110 degree celsius in a 10mm diameter...

Hi there, I am dealing with an inelastic, collinear momentum exchange of the form: m1v1+m2v2=m1u1+m2u2 where m1 & m2 are known. v1 & v2 are both 0 u1 & u2 are both unknown, however MOD(u1)+MOD(u2) is known (ie the sum of modulus of each speed, I don't know how to do straight...

Perhaps this is a bit of a naive question, but I'm having trouble with the following issue. It is easy to describe the motion of a test particle near a black hole using classical general relativity. The underlying assumption is that gravity is a geometric manifestation, and the orbits are...

I've recently found out that my university has an exchange program set up with the U of Cambridge. I am interested in pursuing math in graduate school. I've finished the standard lower-level coursework in math (Cal I-III, Diff eq, and Linear Algebra), plus Analysis I (analysis on the real line)...

Leaving the physics out of this, I'm working on an idea for an in home MHD generator. I'm trying to figure out a conductive fluid to use. I'm back to the idea of salt water, or H20 + NaCl. I know this is a very conductive solution, but I'm no chemist. What I plan to do is put a MHD generator and...

Hello, I arrived here following links to "heat exchange". I've got a small (200amp) tig welder and would like to move up to a water cooled torch. I'm building my own cooler in my workshop. I'm challenging myself to fit a cooler into the smallest package possible, the only limits being my...

Consider a system of two bosons with spin, say photons. The wave function must be symmetric under the exchange of the two particles. For example, |psi> = |up> |down> + |down> |up> So far, so good. Now let us measure the spin of the particles, and let the outcome of the measurement be that...

Homework Statement Let E be the exchange matrix (ones on the anti-diagonal, zeroes elsewhere). Suppose A is symmetric and positive definite. Show that B = EAE is positive definite. Homework Equations The Attempt at a Solution I've tried showing directly that for any conformable vector h...

hi, the standard (?) explanation for particle exchange to produce repulsion and attraction is at: http://math.ucr.edu/home/baez/physics/Quantum/virtual_particles.html this seems to me to have two problems. 1.) in the case of repulsion beteen two electrons, the direction has to be...

Could someone explain me an elementary introduction to this phenomenon ? i know that it is produced whenever an ANTIFERROMAGNETIC and a FERROGMAGNETIC materials are put together , however my doubts are - is this 'exchange bias' produced by any spin interaction ?? - i can see the figures...

Dear all, I read from a book discussing about the scattering that if we consider the scattering of spin-1/2 particles (two particle scattering), we can describe the effect of spin in terms of the "exchange potential operator", which satisfies V_e^{\text{op}}\psi(\mathbf{r}) =...

Hi, I am involved in a project that cools outside air to underground temperatures at 6' below ground in Florida soil. we are using thin wall PVC @ 4" diameter. i am looking for an equation that will tell me how long to make the pipe and what the ideal cfpm should be to achieve desired...

. hi everyone here , i have a problem about the exchange energy . IN quantum mechanics, there is a example how to solve eigenvalue and eigenfunction of helium within the framework of perturbation theory . when two electrons are in different eigenstates,the first order correction of...

Just looking through some old papers and found a problem that I don't know how to solve. Two identical 1.0-kilogram blocks of copper metal, one initially at a temp OC and the other initially at a temp of 100C are enclosed in a perfectly insulating container. The two blocks are initially...

It seems to me that the physics is the same they are all due to the exchange of virtual photons between two particles

When Empathizing, one puts oneself in another's shoes (colloquially speaking). The magnitude of the wave function corresponding to identical particles is invariant under the exchange operator. This exchange interaction; one might say that identical particles are "empathizing" with one...

How does the exchange of photons/virtual photons give rise to the electrostatic or electromagnetic force? Why do like charges repel and opposite charges attract?

Has anyone heard of this title or seen the documentary. Well I was introduced to it by my roommate. I found it very interesting how one sided University's are, the majority of faculty hold very liberal views, I tested this at my own school (University of Washington) and based on my experience i...

I know there is already a post on this, but I just wanted to make a point. I live in California, so obviously there is a great deal of controversy here by the coast and especially where I am (a small conservative community) whether or not warming is legit (long story short, I believe...)...

exchange forces have always confused me. I get the feeling they're made up to explain forces. The exchange of a photon between two electrons makes some sense to me. Conservation of momentum alone would make them repel each other. It makes some sense that on a larger scale this "force" would...

Hi, Was doing a bit of work the other day and I was looking at collisions. Thinking about real collisions compared to ideal ones and the thing in particular which stands out is that often when two vehicles (for example) collide the striking vehicle will continue to travel some distance in its...

is anybody here from Russia? I ask as I'm planning on doing some type of exchange program there, and am looking for schools that have strong physics programs. i'm hoping to go to a school near a city so I get a better chance to experinece russian life.

Hey! Could someone please explain to me what the exchange integral exactly represents? I understand the coulomb integral and the overlap integral, they have nice classical analogs. But there doesn't seem to exist a classical analog to exchange. Thanks

I ran some simulations with a two mass-three springs oscillator. I found that one mass would oscillate for a while and then almost stop. When that happened the other would start moving back and forth. Is there a way I can predict at what rate the masses will exchange energy?

Well its not really a homework question but I have looked through the tutorials and am still at a loss. Homework Statement During weak interactions the particle exchanged is either W- W+ or Z0. The thing is, I get confused which weak interactions involve W- and which involve W+. I know...

Deuterium is heavier then Hydrogen so a metal bonded to H vs. C can be determined by isotopic exchange and then using Infrared Spectroscopy/mass spec. But how do you replace hydrogen with deuterium? a.Dehydrogenation and then add deuterated solvents (heavy water or CDCl3 ..deuterated...

In Helium we find that each energy level specified by (n,l) splits into two sub levels, a singlet and a triplet (this triplet is supposed to be degenerate) I'm sure that this triplet does not turn out to be degenerate because of fine structure. But I'm not sure if the fine structure splitting...

Can gravity be explained by exchange interactions? I am supposed to give a presentation on it, so some explanation as to why or why not would also be very much appreciated. Thanks very much in advance.

Guess what? I made conversation hearts! :!) INSTRUCTIONS: 0) Quote this post and use only the text following the dotted line below (don't forget to delete the ending [/quote'] tag). 1) Fill out the TO: and FROM: fields. 2) I included three lines for your message (you don't need to use all of...

i would like to know more about the heat exchange in mixtures and thermodynamics example would be like: How much heat energy is required to change? a) 2.0kg of ice at 0 C to water at 0 C? b) 500g of water at 100 C to steam at 100 C?

I understand (vaguely) how momentum is exchanged via virtual photons in electromagnetic interactions. But how do the changes in kinetic energy occur? For instance, a proton and electron are at rest separated by a distance x. The proton emits a virtual photon and recoils in the direction of...

All the places I've searched I find that the change in the internal energy for the adiabtic process is dU = C_V\,dT But I don't understand why they use C_V, neither the volume nor the preassure is constant during the adiabtic process.. I know that dU = C_V\,dT = C_p\,dT - p\,dV...

I noticed someone posted on the internet (not on PF of course!) a largely senseless attack on science which contains a discussion of quantum mechanics and the view that neutrons change into protons and protons into neutrons in what they called a ceaseless exchange of identity. I think it's...

Hello, although being graduated in physics (but not being an expert on QED) I find myself embarassed in trying to explain in very simple terms how the electrostatic force arise from the exchange of virtual photon. Especially when it comes to actually reduce all calculations to the expected...

I'm trying to understand the Hartree-Fock mathematical formulation I understand the Coulomb operator, but I don't understand the exchange operator: \hat{K_{j}}[\Psi](\textbf{x})=\Phi_{j}(\textbf{x})\int d\textbf{x}'\frac{\Phi_{j}^{*}(\textbf{x}')\Psi(\textbf{x}')}{|\textbf{r}-\textbf{r}'|}...

I've been reading Giancoli (Physics for Scientists and Engineers, 3rd Ed) and Griffiths (Intro to QM). There seems a contradiction on the applications of the Energy-time uncertainty principle between the two. Griffiths claims that energy is always conserved, even though mathematically...

hello all I never really understood the future exchange Market. Can anyone explain it to me in detail, any information would be helpful? thank you

What is the exchange rate for RMB to US $? i.e. 1 RMB = x US$.

why is it acceptable to assume any heat exchanged with the surroundings of a system is a reversible heat exchange? The only explanation I can find is that it's because the surroundings are essentially unchanged by the heat they absorb...but I don't understand that as an explanation. I take...

For a hydrogen/deuterium exchange experiment, the protein of interest is first incubated at pD = 7, after which it is quenched at pH = 2-3. Why it the exchange done at a neutral pD and why has the exchange of hydrogen atoms a minimum at pH 3?

In Yukawas model the force between nucleons comes from the exchange of a pion. How precisely does this lower the energy? Has it something to do with confinement energy? I know an exchange force can be understood in terms of a momentum exchange by the force carrying particle. But there must...