Coupling Definition and 355 Threads

Homework Statement Compute the cable-to-cable crosstalk due to capacitive coupling in a harness between two cable pairs having an average separation distance of 3 mm and a 10 m in a cable tray. The cable diameters are 1 mm and both cables are operating at a 100 ohm impedance level. Assume h = 5...

Hey all, I am a graduate student (in chemistry) working on oxide crystals. Our group has a SQUID magnetometer which we use for magnetic property measurements. The other day a fellow student and myself got into a discussion about LS coupling and crystal electric fields. I know that CEF will...

I know that QFT puts in the coupling constants by hand, based on experiment. And many of the coupling constants are suppose to become equal at the grand unification energy. But I wonder if there is any principle that would allow us to calculate the present day coupling constants based the GUT...

The thread name is probably misleading, but I just want to make sure I'm clear in that: Are the only two problems caused by leakage inductance (stray magnetic flux causing imperfect mutual coupling) in a transformer, that of; - poorer voltage regulation & - EMI noise on other equipment (?)...

Homework Statement [/B] We have that the three lowest energy states of a system are $$ ^3F_2, ^3F_3, ^3F_4 $$ (these are the Term symbols) with relative energy gap $$0,\ 171,\ 387 \ cm^{-1}$$ Now using the perturbation $$H_{LS}=\beta \ \vec{L}\cdot \vec{S}$$ i have to find the best value of...

Hi all, Has anyone an idea about the loop correction for quartic Higss coupling? In [arXiv:1507.03618v2 [hep-ph]], equ. (13) it's pointed out that the perturbativity constrains on the quartic couplings in the Higgs potential is ## \lambda^2 < 16 \pi^2 ## Which means that loop factor is ##...

Homework Statement [/B] I've been working my way through the following question but I am a little bit stuck at this part: A gearbox and flywheel are as shown in FIGURE 4. The output shaft rotates in the opposite direction to the input shaft at 5 times its speed. The gearbox has an efficiency...

Hi All 1. Homework Statement with the known coupling strenght between SM neutrinos and Z boson Z_{\mu} \bar{\nu}_{L} { \gamma}^{ \mu} \nu_{L} how can I get the coupling strength for Dirac neutrinos Z_{\mu} \bar{\nu}_{Dirac} { \gamma}^{ \mu} (1- { \gamma}_{ 5} ) \nu_{Dirac} ? thanks

So we obtain the perturbation Hamiltonian H as something proportional to S.L/r3 and the first order energy shift is then the expectation value of this perturbation Hamiltonian in the state that is being perturbed. So let a general gross structure state that we are perturbing be |n l ml s ms >...

How can I derive the running coupling for the weak interaction. I have found derivations for QED and QCD that involve the β function http://www.physics.umd.edu/courses/Phys741/xji/chapter1.pdf but I can't find anything specific for the WI. Thanks.

Hi, I have been having this question for a long while. From Pozar's book (Microwave Engineering), on page 336, when he was solving for the resonance response and the Q factor for a Lamba/2 resonator terminated by an open circuit, and coupled to the feed line through a series capacitor, at some...

Homework Statement How can I solve this hamiltonian equation? H= p2/2m +α/ħ (σxpy - σypx) + γ/ħ (σxpx - σypy) + βxσx + βyσy Homework Equations Rashba coupling effect equation: HR=α(σykx - σxky) The Attempt at a Solution H0=ħ2k2/2m + HR+ HD

The beta function is defined as: \beta(\lambda)=M\frac{d}{dM}\lambda If we make the substitution t=ln(p/M) the above equation becomes: \beta(\lambda)=-\frac{d}{dt}\lambda Now if we use e.g. the QED beta function \beta(e)=\frac{e^3}{12\pi^3} and for e(p=M)=e_0 the result is...

Homework Statement i need to couple a ray (point source 15 deg) into a fiber with a small core diameter, the fiber located 8cm from the source. the focal distance of the lens is 1.5cm i need to choose 2 possible locations Homework EquationsThe Attempt at a Solution first suggestion: i placed...

Hello, I can't understand where this formula ((8.5), Rössler, Solid State Theory, Springer) comes from (see attached file). The label l stands for the electrons positions and c and c dagger are the free electron creation and annihilation operator. This expression is used to write the linear...

Good Day, I am looking for mathematical modelling of Joule heating of a simple cantilever beam . Can anybody provide me good source of relevant material. Thanks in advance.

Hey, we are trying to couple the light of a 75 W Xe Arc Lamp (Hamamatsu L2194) into a 800um(0,8mm) diameter fiber bundle (7 fibers). Now we have 2 plano convex lenses (25mm diameter, 30mm EFL, edmund serial #45-364), the first for collimating the second for focusing onto the fiber. We are...

Hi, in class I'm doing a Suzuki Cross Coupling reaction based on "Nickel-Catalyzed SuzukiMiyaura Couplings in Green Solvents" by Stephen D. Ramgren, Liana Hie, Yuxuan Ye, and Neil K. Garg. The reaction involved the bromo-aryl reacting with the boronic acid in heated t-amyl alcohol in the...

When a coupling is described as being 6.35 mm x 12 mm, what does this mean? I figure that 6.35 mm is the shaft diameter it accepts because that diameter equals 1/4". Is 12 mm the size of shaft the opposing side is designed to attach to? Thank you in advance.

I have some doubts about minimal coupling of a field of spin 2 for example, with the electromagnetism and I hope someone can help me to clarify them. According to Pauli and Fierz one couples the field with electromagnetism introducing the covariant derivative at the level of the Lagrangian...

Hey, I've been trying to figure out why a protons in identical environments will not undergo spin-spin splitting with one another. From what I understand splitting of a signal for a proton is due to the nucleus of another nearby either opposing the external magnetic field or acting in the same...

Hi i'm looking for some references (prefer books) or explanations as to how one couple electrons so an EM field in a second quantized formalism tight binding model. from what i know, one need to replace the hopping parameter with the same parameter multiplied by an exponent of the line integral...

Just a simple question -- can the dimension of coupling constant be a rational number or should it always be an integer? The question arose when I was trying to construct a Lagrangian with an interaction term involving two spin-1 particles and a fermion. The dimensions add up to 7/2, which...

Consider the Hamiltonian ##H = - \frac{d^2}{dx^2}+gx^{2N}##. Scaling out the coupling constant ##g##, the eigenvalues scale as ##\lambda \propto g^{\frac{2}{N+2}}##. So, we can drop the g dependence and just consider the numerical value of the eigenvalues and the associated spectral functions...

I'm learning QFT from Srednicki's book. He introduces dimensional analysis in section 12. Coupling constant needs to be dimensionless in order to avoid a number of problems. So phi-cubed theory needs 6 space time dimensions to make sense, but isn't phi-4th-powered theory just right for our 4...

Dear everyone, For example, the simplest action for a nonminimally coupled scalar field is S=\int d^{4}x\sqrt{-g}\left[ \frac{1}{2}g^{\mu \nu }\partial _{\mu }\phi \partial _{\nu }\phi -V(\phi )+\frac{\xi }{2}R\phi ^{2}\right]. \xi=0 leads to the scalar field minimally coupled to the...

Hi, if I simulate a three phase transmission line operating with a fault across two of the phases, would the mutual coupling have any effect on the current through each of the lines, as I have calculated the fault current values using symmetrical component analysis and the values are...

Hi! I´m a dentist and I own a couple of surgical loupes... I´m a DIYer for the fun of it, but I´ve got a limited knowledge in physics... I´d like to adapt a CCD (I´ve got one from a webcam) to the eyepiece of my loupe´s ocular... So I can take pictures or even film what I´m seeing so I can show...

Problem: I am having a bit of problem with the signs on the force balance with the constraining force. The system is: Attempt: I drew the FBD with the constraining force for the lumped mass: Then I tried to solve for the constraint force in terms of the spring and damper: For the...

I'm an experimentalist, so go easy on me... What does it mean for a particle to either couple or not couple to a field? I haven't taken a class in QFT yet, so please try to explain the general idea without any details or equations!

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...

Hi, I wonder if a theory like 2HDM has a new triple Higgs coupling, like ##g_{hH^+H^-}##, what governs how much is this coupling ? For example a paper as : arXiv:1405.3584v1 [hep-ph], they normalize ##g_{hH^+H^-}## by the SM ##g_{hWW}##, they plotted at fig. 3 (f)...

Hello, I am trying to design a way to move a platform that is inside a container without any direct connection to the platform. I hope to have a linear guide outside of the container with an electromagnet attached. When the electromagnet is energized it will couple with the platform...

I have an FPGA demo board and on the GPIO I have attached a 4 x 3 membrane keypad. This keypad is simple, create a current on the column pins and look for a completed circuit on the row pins. http://ebay.arduinodiy.co.uk/ebayimages/ebaycontent/kppinout2.jpg...

Hello to everyone, I got a little bit confused between the coupling constant g_W and the strength parameter \alpha_W in the weak interaction. For what I know they should both give an idea of the strength of the interaction but I miss to understand what's the difference between them.

Can anyone explain why the energy levels separate as a result of spin-orbit coupling? Also, what determines the *new* number of "sub-levels" which are obtain after the original energy levels are separated as a result of spin-orbit coupling? Please give examples, if you want, using the...

In a perfect periodic crystal, do lattice vibrational modes corresponding to different wave vectors (k-vectors) interact with each other? I'm asking with reference to anharmonic lattice-dynamics calculations of a time-independent nature. For example: consider a linear, monatomic chain with a...

I had a 4:1 single phase step-down transformer. Primary winding was provided the mains supply (225V) and output (secondary) was 57V. I was under the impression that capacitive coupling b/w primary and secondary was noticeable only in high-voltage transformers, and thus in this case (low voltage)...

The Schrödinger equation rotates the state vector in Hilbert space continuously (i.e. without jumps). This makes sense for individual systems, but I'm finding this hard to reconcile with coupling or entanglement. For example, consider how Schrödinger's cat paradox is typically presented (in...

Is it just a series of attracting magnets in a circle?

Hello, I see a Hamiltonian of spin-orbit coupling, it is like this H=\frac{1}{2m} \sum_{\alpha} \left( \left( -\partial_{\alpha}^2 - 2i\kappa_{\alpha} \sigma_{\alpha} \partial_{\alpha} \right) + \kappa_{\alpha}^2\right) Here \hbar = 1. \kappa_{\alpha} is the strength of spin-orbit...

I am not clear on why different models of coupling are useful in different situations. In general, J = L + S For small atoms, LS coupling dominates the angular momentum related component of the Hamiltonian. That means we calculate: Ltotal = l1 + l2 + ... Stotal = s1 + s2 + ... and...

Hi PF members. I have got a little worry I am familiar with the Zeeman term that always appears in the Hamiltonian of a spin chain representing the influence of an external magnetic field. I don't know if there is a similar term if the spin was rather in he presence of an electric field ( I...

Perhaps I'm confusing two different things but I've read online (http://en.wikipedia.org/wiki/Gravitational_coupling_constant) that the gravitational coupling constant is dimensionless and proportional to Newton's constant G. However, I have also read that the gravitational coupling constant...

Hello, I have a small question about coupling of angular momenta. When you have J² with J = J1 + J2; you change it to the form (dropping the hbar in all equations): j² = j1² + j2² + j1-j2+ + j1+j2- + 2j1zj2z now it's these j1-j2+ I have a problem with. Let's say you use it on |1/2;-1/2>...

Can a weak alternating magnetic field from one coil have an effect on another coil that has a stronger alternating magnetic field? I ask this because I want to know if magnetic fields follow the same principal as coupling two different voltages together.

Is adding a coupling capacitor to the generator necessary when injecting a signal for troubleshooting.

I am interested in the following scenario. Suppose that you have a composite system, e.g. ion, atom or whatever you want. This system will have internal degrees of freedom (d.o.f.), i.e. relative positions and momenta, and also center of mass d.o.f..What i am looking for is to find an...

Hello Guys ! While Studing coupling transformers i found this problem i tried to solve it but i don't know if my solving is right or no ! so tell me :) The problem : My solve is : V(out)=nV(in) V(out)= 2 * 312 = 624 v PIV = V(out) = 624 v and if the diode is turned...

Hey all, Just a question concerning the image I have provided. If I have an offset of 0.1 mV at the non inverting input, how exactly does coupling take effect in this set up? If I input an ac signal, it will pass through the cap, but will the op-amp not still experience the offset voltage?