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0answers
100 views

Solenoid core and magnetism

I understand the core of a solenoid can help increase magnetic field produced by a given current and every metal has a specified permeability $\mu$, but what if we had a hybrid core, say 50% iron ...
0
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0answers
21 views

Are the polarization field and electric field in LIH dielectric in dynamic equilibrium?

If we know that the Polarization P in LIH dielectrics is proportional to the net field inside the dielectric according to: P = ε0χeE.....(1) And we know that D = εE........(2) Does it not follow ...
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0answers
77 views

Finding kinetic friction coefficient

A box is thrown up an incline with degree $\alpha$. the kinetic-friction coefficient is $\mu_k$. the body returns back to its start point. a. prove ...
0
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0answers
118 views

One-loop beta functions of the Standard Model

For my master's research on energy scale independent combinations of renormalization group equations in supersymmetric theories, I need an overview of all the one-loop beta functions of the Standard ...
0
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0answers
69 views

How to relate compression ratio to work input for a compressor in a heat pump

So I need to calculate the COP (Coefficient of Performance) for a 6-ton air conditioner system in terms of the compression ratio. I understand that: $$COP=\frac{Q_L}{W_{net,in}}$$ I cannot find out ...
0
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0answers
365 views

Elastic Ball Collision and contact angle

For a project I need to make a good simulation of balls moving around in a space. The project will be without any air drag and without losing energy in bounces. Since there is no way to lose energy ...
0
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0answers
47 views

What's the typical material used as a low-k ILD in semiconductors?

Semiconductor companies (namely IBM, Intel, TSMC and etc.) may use different low-k materials as inter-layer dielectric (ILD) in their fabrication process. I'm wondering what is the most typical one. ...
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0answers
30 views

Implications of a phase shift in a 2-ray propagation model

So I am working with a 2-ray (actually it's 8 ray now, but that's merely an extension) wireless signal propagation model. The equation of the component of interest: $ P = ...
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0answers
77 views

Why do I get different colours in scratched holograms?

I was making a scratched holograms and in result got different colours instead of white hologram
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0answers
30 views

How to represent a multiple in the frequency domain

So, in my previous question Where does this formula for prediction of a multiple wave come from?, I get that using this picture: we have so far written the time it takes for a multiple to travel ...
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0answers
53 views

normal ordering from anti normal ordering of creation and anhilation operators

I am working on entanglement of systems in beam splitters. I constantly come across equations of creation and annihilation operator (ladder operators) in anti normal ordering. I want those equations ...
0
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0answers
31 views

How can a transversality condition be invoked to reduce the Euler-Lagrange equation?

I asked this question regarding the Euler-Lagrange equation at MSE and have gotten no response. I will ask it here too. I think I might have more luck here since the E-L equation is at the core of ...
0
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0answers
60 views

Deduction of relativistic mass formula in 1+1 dimensions

I have read the explanation/calculation of relativistic momentum and relativistic mass in the Feynman lectures, see chapter 16.4 here: http://www.feynmanlectures.caltech.edu/I_16.html. (I guess this ...
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0answers
81 views

How to use The Schwarzchild Metric formula to get distribution representing “free-fall”

Given formula: How I can use to calculate distribution of points in space, so if i choose path which contains most of the points I get path that close to "free-fall path". As far as I know i should ...
0
votes
0answers
139 views

Parity Transformation Behavior of (Weyl-)spinors

Suppose $u^\pm (p)$ are Weyl-spinors with helicity $h = \pm$, i.e. solutions of the Dirac equation $p_\mu \gamma^\mu u(p) = 0$. How do these spinors behave under parity transformation? In ...
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0answers
172 views

Probability of absorption and emission of photons

Suppose you have a single electron in a box, and you shoot a single photon at it. How does one calculate the probability that the photon will be absorbed and the particle excited? Or that the photon ...
0
votes
0answers
38 views

Does the plasma move in the tokamak?

I was reading about tokamaks, for usage in fusion, and it seems that the positive ions circle in one way in the toakmak, while the negative circles in another. That would make a lot of sense, as it ...
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0answers
29 views

References requested on departments with recitation sessions

What physics departments offer recitation sessions for their physics courses on the undergraduate level? If there is a site which has such info it will be greatly appreciated.
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0answers
176 views

Continous and Discrete basis, Multiplication of Density Matrix and Hamiltonian

Suppose I have a wave function $\psi(x)$ in position basis. I can make a density function by simply multiplying $\psi(x)$ and its conjugate $\psi^*(x)$. If I operate the density matrix ...
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0answers
85 views

force on two particles moving with same velocity

When two charged particles having same charge $q$ are at rest, only electric force acts upon it: a repulsive force of magnitude $\frac{kq^2}{r^2}.$ Now let them move with a constant velocity ...
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0answers
84 views

On motivation for the definition of ADM mass

The ADM mass is expressed in terms of the initial data as a surface integral over a surface $S$ at spatial infinity: $$M:=-\frac{1}{8\pi}\lim_{r\to \infty}\int_S(k-k_0)\sqrt{\sigma}dS$$ where ...
0
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0answers
122 views

Solve a problem without using separation of variables

There's an additional exercise from Introduction to Electrodynamics by Griffith. Problem 4.34 A point dipole p is imbedded at the center of a sphere of linear dielectric material (with radius $R$ ...
0
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0answers
35 views

Yan - Drell process

I'm looking for more information about Yan - Drell process but didn't manage to find a good place to learn from (still looking for one). I understood that this process can help us to understand the ...
0
votes
0answers
24 views

Frequency response of the wireless channel

We know that the signal attenuates out with distance and according to the channel transfer function or frequency response, the signal frequency components attenuate to different values based on ...
0
votes
0answers
43 views

Phased array radar equations

Suppose we have several antennae to transmit and receive radio waves. What should one transmit, and what kind of equations are used to compute $reflectivity(\vec{x})$ for points in space from a given ...
0
votes
0answers
109 views

Single photon double slit experiment

In the question Double Slit experiment with just one photon or electron, one of the answers says There have been experiments recently where one can detect which the slit the particle went through ...
0
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0answers
154 views

Reference request: Hollow concave Earth hypothesis

Reference request concerning the Hollow concave Earth hypothesis. I am searching for this paper: A Geocosmos: Mapping Outer Space Into a Hollow Earth authored by M. Abdelkader and published in ...
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votes
0answers
114 views

Definition and Measurment of Energy and Heat in Thermodynamics

The concept of work is clear from mechanics, where $dW=F\cdot dx$, leading to $dW=PdV$. Also different forms of energy are defined in mechanics, e.g., $E=\frac{1}{2}m v^2$, etc. How are the energy and ...
0
votes
0answers
50 views

Why isn't the 3 pts function vanishing in the Ising model by Z_2 symmetry?

The Ising model with vanishing external field possesses the $Z_2$ symmetry: $$\sigma_i \rightarrow - \sigma_i$$ implying that the 1 pt function vanishes: $$<\sigma_i> \;= 0$$ In the same ...
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votes
0answers
50 views

Relationships between sinusoidal signals and spatial extrapolation of tides?

I'm trying to relate a near shore tidal signal (point A) to 3 points along a long model boundary (points B C D). I want to possibly have a relationship between B C D with which we can convert A ...
0
votes
0answers
53 views

Flow of water through sand

Imagine a set up with a column of sand with porosity $\phi$ and permeability $k$ contained in a cuboid container. When one pours water evenly (let's say $V_w/A$ cubic meters per square meter) on the ...
0
votes
0answers
72 views

Finite Square Potential Well Solving

I've got a question about solving the finite square well. Consider a 1D finite, square, potential well where: $$ V(x) = \begin{cases} 0&\,{\rm if} x<0 \\ -V_0&\,{\rm ...
0
votes
0answers
138 views

Interpreting a Hamiltonian in terms of 'hopping' operators

I am having some trouble interpreting a Hamiltonian in terms of "hopping" operators. The Huckel model for nearest neighbour interaction in graphene is given by $$H=-t\sum_\vec{R}|\vec ...
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votes
0answers
24 views

Calculating the stability/invertibility of energy maps by multivariate time series model

You have the following energy maps for 14 different structures so about 4-5 pixels for one unit. The color density represents energy. I am thinking that you can set multivariate time series models ...
0
votes
0answers
58 views

Superposition of waves hitting at right angle

I'm considering, in general, a spherical wave coming from a pin hole and landing on a wafer, both directly and off of a mirror. The mirror and wafer are at right angle. If it weren't a pin hole, and ...
0
votes
0answers
58 views

The far $\vec{\mathrm{E}}(\vec{\mathrm{r}},t)$ field of an arbitrary antenna given an arbitrary input current $I(t)$

I was wondering if the following expression is reasonable to express the far $\vec{\mathrm{E}}\left(\vec{\mathrm{r}},t\right)$ field for an arbitrary antenna that is fed with an arbitrary time-varying ...
0
votes
0answers
23 views

Would the microwave background radiation have an “observer effect” on all systems in the universe due to its permeation?

Or more specifically, does the CMB radiation have an observer effect on us in our local system due to gravitational lensing? Acknowledging this effect, if any would be nearly negligible I have an ...
0
votes
0answers
76 views

How can I model computationally or experimentally the flow in my aquarium tank?

I have a 60-gallon aquarium tank and I have always wondered about the flow of water in the tank. Let's represent the flow of water in terms of a direction field representing velocity, so if we see the ...
0
votes
0answers
37 views

why using a EM spectrum produces a narrower fringes

I'm trying to figure out a physical reason of why a broader pulse turns out to give a narrower fringe, although I know mathematically the fringe is just the fourier transform of the pulse on the ...
0
votes
0answers
32 views

Coherent Population Trapping

I'm researching a review article I'm writing on atomic clocks. In miniaturized versions of the technology they are using coherent population trapping to excite resonance in atoms. I don't really ...
0
votes
0answers
40 views

Entanglement entropy at finite temperature

The entanglement entropy is computed on a constant time slice. At finite temperature the time is periodic. How then can the entanglement entropy be calculated on a constant time slice? For example ...
0
votes
0answers
57 views

How long do virtual photons exist for in the Sun's magnetic field?

The Sun's magnetic field goes all the way out to the heliopause which is a very long distance to travel and magnetic fields consist of virtual photons so how long do these virtual photons exist for to ...
0
votes
0answers
85 views

Confused about elasticity and collisions

I was solving the following problem and the explanation to it confused me. There are two objects with mass $m$ and $M$, respectively. The object with mass $m$ has a velocity of $\sqrt{2gl}$ and ...
0
votes
0answers
60 views

origin of cusps in simulated dark matter halos

I keep reading that cusps are one of the most "robust" predictions of N-body simulations of dark matter halos. But any paper I've found on the topic makes it sound like these simulations are ...
0
votes
0answers
62 views

Force on an electron at an arbitrary point inside a cylinder (electron gun)

I want to simulate the path of an electron through the anode of an electron gun. I therefore need to calculate the force on the electron due to the electric field from the anode and apply that to its ...
0
votes
0answers
33 views

Increasing number of neutrons in nucleus

I understand that the neutron-proton bonds in the nucleus creates the strong nuclear force but,how does increasing the number of neutrons in a nucleus affect electrostatic force, nuclear force and the ...
0
votes
0answers
30 views

Properties of material affecting magnetic refrigeration

I am reading about magnetic refrigeration at the moment - I see that two factors affecting the applicability of the material for use in magnetic refrigeration is that they must react strongly (i.e the ...
0
votes
0answers
170 views

2D Ising model simulations: Wolff algorithm acceptance probability with an external magnetic field

I have implemented the Wolff algorithm to simulate a 2D ferromagnet. It works by building a cluster of like spins and flipping them all at once to move quickly through phase space. In the case of no ...
0
votes
0answers
34 views

Does the direction of perceived time depend on location in the universe?

Do the laws of physics allow for the possibility that in a galaxy far far away, the perceived arrow of time is in the opposite direction to ours, where people (aliens) die before they are born, and ...
0
votes
0answers
65 views

Transformation of a time-dependent acceleration to another frame

How do I transform a time-dependent acceleration between to rest frames? I was given a particular problem and while I found possibilities [1] [2] for acceleration-transformations when the acceleration ...

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