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I know that surface charge density is inversely proportional to the radius of curvature of a surface, but since the radius of curvature of a conducting sheet is ∞, and I know its charge density is not 0, is this an exception or is there something wrong in the way I understood the relation?
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Reference material (free access right now): Shankar
On page 81 of Shankar, (paraphrasing) he states that:
$ 1: T$, the kinetic energy in polar coordinates, depends solely on $\frac{d}{dt} \phi$ if $\frac{d}{d \phi}V=0$, where $V$ is potential energy.
I would like to prove this statement.
He showed us how to calculate ... |
I have read almost everywhere that the biggest questions in physics is to unify all the fundamental forces but I simply do not understand why do the forces have to follow a same set of rules or why is unification of Forces necessary?
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We know that two parallel planes have the same Miller indices so we can have an infinite number of parallel planes close to one another all of which have the same Miller indices.
But it's claimed that
the interplanar distance between two adjacent planes is given as $$d_{hkl} = \frac{a}{\sqrt{h^2+k^2+l^2}}$$.
I can't ... |
I am wondering if there is a simple experiment that can be performed at home to demonstrate the formation of galaxy with arms and no arms(density is smoothly spread out)? The experiment must help explain the actual formation of these two distinct galaxies.
|
Consider the circuit given below, At the lower left corner of the circuit assume potential to be $0\ V$ , Now at the upper left corner current should be $9\ V$ and similarly at the upper right corner, According to Ohm's Law, as potential difference is $= 0$, there shouldn't be any flow of current, yet there exists con... |
It is well known that for each symmetry in the system there must be a conserved quantum number, I would like to know what are the conserved quantum numbers associated with inversion and time-reversal symmetries. For example, in the continuum approximation AB-stacked bilayer graphene has the following Hamiltonian:
$H=\l... |
I'm aware that Newton's 2nd Law is covariant under a Galilean transformation or under any other linear transformation that's not parameterized by relative velocity of frames.
But what about non-linear transformations like change from Cartesian to polar coordinates (strictly speaking not a change in reference frame - ju... |
In the principle of stationary action, the initial and final points in configuration space are held fixed. This is a boundary value problem. However, this principle leads to the Euler-Lagrange equation which is a differential equation and an initial value problem. The end point of motion does not appear anywhere in the... |
The Diamond Lattice (e.g. here) is an fcc-lattice. For an fcc-lattice,
one set of primitive translation vectors could be
$\left\{ \frac{a}{2}\begin{pmatrix} 0 \\ 1 \\ 1 \end{pmatrix}, \frac{a}{2}\begin{pmatrix} 1 \\ 0 \\ 1 \end{pmatrix}, \frac{a}{2}\begin{pmatrix} 1 \\ 1 \\ 0 \end{pmatrix} \right\}. $
However, this set... |
Many quantities in physics are defined as ratio of infinitesimal quantities. For example: $$\rho(x)=\frac{dm}{dx}$$
or
$$P(t)=\frac{dW}{dt}$$
Are these quantities actually derivatives? I mean if we want to calculate density it wouldn't make sense to select a infinitesimal length element $dx$ and then measure the mass d... |
I have come across various ways one refers to a process as stationary and cannot seem to get the equivalency and the level of rigor in each of them:
According to Stochastic processes in physics and chemistry by Van Kampen, a stationary process is one for which the probability distribution for the stochastic variable i... |
I have a function $f$ mapping a bit onto another bit, i.e. $f : \{0, 1\} \rightarrow \{0, 1\} $. The function f is either constant,
so f(0) = f(1) or balanced, so f(0) $\neq$ $f$(1). The quantum gate for the Deutsch algorithm is given below
The second gate f has the following form:
$U_{f}$ : $|x,y \rangle$ $\rightarro... |
Given the following Lagrangian,
$L=\frac{1}{2} g_{i j} \dot{q}^{i} \dot{q}^{j}+b_{i j} \dot{q}^{i} q^{j}-U(q)$
I am told that,
The eom depend only on the anti-symmetric part of $b_{i j} .$ The reason is that the symmetric part of $b_{i j}$ contributes a total time derivative to $L .$ Indeed,
\begin{aligned}
b_{i j} ... |
I've searched a lot, but have not been able to find a proper explanation for the working of a control moment gyroscope. Could someone please explain it to me, preferably with vectors?
|
I was wondering if light can travel faster when it is within a region of moving spacetime. I know in general, that when you move a medium such as water, like in a river, water waves travel slower when against the current and faster when along with the current.
Is this true with light? It seems to me that when light is ... |
According to this paper, https://doi.org/10.1103/PhysRevB.2.4559, the electron (wave packet), moving along $x$ axis, undergoes a transverse shift $Δy$ after collision with spin-orbit coupling center. How to make sense of this?
I can understand a continuous transverse drift due to SOC (skew scattering) as an effective f... |
I am studying the 't Hooft's paper "Topology-of-the-gauge-condition-and-new-confinement" https://doi.org/10.1016/0550-3213(81)90442-9 and there are several points which I would like to understand.
In the section 2 of the paper he considers the Abelian Higgs model, and at first takes chooses the unitary gauge condition ... |
Any skew-symmetric tensor $ F_{\alpha\beta} $ which is the curl of a 4-vector $A_\mu$,
that is each tensor having the form
$ F_{\alpha\beta} = \partial_\alpha A_\beta - \partial_\beta A_\alpha $,
will satisfy the relation
$$
\partial_\alpha F_{\beta\gamma} +
\partial_\beta F_{\gamma\alpha} +
\partial_\gamma F_{... |
I know that for standard QCD with quarks, chiral symmetry breaking occurs for around 4 - 5 light/active quarks - i.e. pions, or generally pseudoscalar goldstone bosons, definitely appear in the spectrum for $N_f=1,2,3,4$.
My question is, within $N_f=1,\ldots, 4$, how does the pion decay constant vary with respect to $N... |
Suppose that you have a flat universe described by the FRW metric.
$$ds^{2}=-dt^{2}+a^{2}(t)(dx^{2}+dy^{2}+dz^{2})$$
Then if you want to know the distance that a light ray travels from time $t_{e}$ to the present day $t_{0}$, you can make the following calculation:
$$dt^{2}=a^{2}(t)(dx^{2}+dy^{2}+dz^{2})\equiv a^{2}(t... |
It is well known that in static system, electric potential energy of system conducted with two sphere charges, $q_1$ and $q_2$ with distance $d$ and radius $R$, is $E=\frac{q_1 q_2}{4\pi\epsilon_0 d}+\frac{q_1^2+q_2^2}{8\pi\epsilon_0 R}$. But what if the charges are moving? Not just moving slow, but with high speed eno... |
In the context of Special Relativity, so in flat spacetime, and with the metric tensor $g_{\mu \nu}$ chosen with the signature: $(+,-,-,-)$, lets consider the following four vectors:
$$x=(x_1,x_2,x_3,x_4)$$
$$y=(y_1,y_2,y_3,y_4)$$
the Minkowski inner product between the two is:
$$x^\mu y^\nu g_{\mu \nu}=x_1y_1-x_2y_2-x... |
Consider a system of two masse $M$ and $m$ with $m<<M$ and the mass $m$ orbiting around $M$. Then $m$ describes a elliptic orbit with period $P$ and the third Kepler law states that:
$$\frac{P^2}{a^3}=\frac{4\pi^2}{G(M+m)}\approx \frac{4\pi^2}{GM}$$
with $a$ the semi-major axis. It means that if I have a heavy planet w... |
The Weyl-Wigner representation is a useful tool to study QM from a semiclassical, phase-space point of view. My question is simple: if this method is so close to classical mechanics, why don't we use it for the whole theory of QM? Why do we need Hilbert spaces?
|
Suppose I have a mass $m$ kept on a horizontal table with coefficients of friction $\mu_{s}$ (static) and $\mu_{k}$ (dynamic/kinetic). And suppose I have a spring with spring constant $k$ which is attached to a wall perpendicular to the table . Now, if I press a mass against the spring and let it go, will the mass move... |
In the July issue of Scientific American, in a brief article by Charlie Wood on detecting gravitons by looking for long-wavelength radio waves that some of the graviton have turned into, it says,
...other massless particles can abruptly change state in large numbers (a phenomenon known as a quantum break).
Perhaps ne... |
I am trying to derive the expression: $\tau=\mu\times B$, for a circular current loop in a uniform magnetic field. $\mu$ is the magnetic moment of the loop, so it will be $\mu=IA$, where A is the area vector of the loop. So here is how I tried to prove the expression:
$$dF_m=Id\textbf{l}\times B$$
$$d\tau=r\times dF_m=... |
As discussed in this question: How does a wave packet get scattered? And shown in, for example, this video: https://www.youtube.com/watch?v=iq4lGVznr_8
In quantum mechanics particles are scattered due to potentials.
In QFT, specifically QED, scattering occurs due to an interaction term in the QED Lagrangian.
Time evolu... |
If the mass is small enough, we can approximate to the GEM (gravitoelectromagentism). In this apporximation, we can calculate the energy density of gravitational field, such as $u_g=-\frac{g^2}{8\pi G}$ for field generated by mass that is at rest. As you see, the energy density of gravitational field can be negative, b... |
If I have an hydrogen atom at $T=0K$ from Boltzmann distribution I can have only the G.S populated, so if I send to this atom photons at all energies is impossible to excite the atom, is this right? If this is right, the energy spectrum of this atom would be flat?
|
Is it possible to achieve magnetic levitation (rail) using permanent magnets? So no electromagnets or superconductivity. If yes, how? If not, why not?
|
If work done by a conservative force in a closed loop is zero then why is the work done by a non conservative force not equal to zero. Since in both the cases the body moves in a closed path so the displacement must be equal to zero.
|
Reading this question I thought of an argument that an electron's trajectory would bend in the gravitational field despite the electron's being incapable of strong interaction; this would then disprove the conjecture stated in that question. But then I couldn't find any references to actual experiments that have been d... |
Just a simple question: is it correct to say that the Lie algebra of ${\rm U}(1)$ is formed by the generator $e^{i \pi}$?
Is it correct that ${\rm U}(1)=S^1 = T$ is the circle group?
|
I'm not sure if this is an appropriate question for this site, but figured I'd give it a shot. I'm a mathematician (with an extremely limited background in physics) and have come across some ideas that seem related to the concept of holographic entanglement entropy as introduced by Ryu-Takanayagi. However, I'm having... |
Let the action functional $S[q]$ given by
\begin{equation}\label{eq16}
S[q]=\int\limits^{t_2}_{t_1}L\left(q^i(t),\dot{q}^i(t)\right)dt.\tag{1}
\end{equation}
Also, we know that using Legendre Transform the hamiltonian $H(q^i,p_i)$ is related with $L(q^i,\dot{q}^i)$ by
\begin{equation}
L(q^i,\dot{q}^i)=p_i q^i -... |
I am trying to find a mathematical model to show the relationship between B and H when a magnetic field is applied through an iron ball bearing. For simplicity, the ball bearing is 100% iron and also has a diameter of 5 mm. Is there a way to obtain an equation that expresses the B-H relationship?
|
In Peskin & Schroeder, page 97, the following expression is given as part of the demonstration of how the $n$-point correlation function is calculated using connected diagrams:
$$\sum_{\text{connected}}\sum_{\text {all }\left\{n_{i}\right\}}\left(\begin{array}{c}\text { value of } \\ \text { connected piece }\end{array... |
I have a question concerning Mermin's 1967 paper "Existence of Zero Sound in a Fermi Liquid". The condition on zero sound is given by the equation
$$\lambda_n>\eta^{-1}\int \frac{d\hat{n}}{4\pi}|\chi(\hat{n})|^2\cos\theta+\int\frac{d\hat{n}}{4\pi}\int\frac{d\hat{n}'}{4\pi}\chi^*(\hat{n})B(\hat{n}\cdot \hat{n}')\chi(\ha... |
I'm trying to understand the Rashba spin orbit coupling induced in graphene by proximity effect with Au(or any other metal)adatoms. It is not really clear for me. I know that the Rashba spin orbit coupling is obtained by the presence of an Electric field which induced to break the inversion symmetry of graphene(A and B... |
I have a simple question about the electric potential and electric potential energy.
The gradient of the electric potential gives us the electric field,
and the gradient of the electric potential energy gives us the force.
Am I correct in my statements or no?
|
If I place a droplet of oil, which is less dense than water, at the bottom of a glass of water, it should start to rise in the water due to the buoyant force.
Will the oil droplet start rising faster and faster in the water? Like a rock falling down a cliff, which increases its velocity as it falls? And, if so, is ther... |
A CD acts as a diffraction grating and a circle of colors can be seen in a wall using the sun as a source of light.
However I tried several types of lamps (incandescent, fluorescent and LED's) and could not produce the same effect. The iridescence can be seen on the CD surface, but not on the wall.
One of the lamps ha... |
I often hear that neutron stars emit 30-40% of their energy as neutrinos.
But how many neutrinos do neutron stars emit per second ?
|
I have a very silly doubt. If I have two coordinate systems and I want to calculate the coordinate differentials for the second one, I need to use the chain rule for the derivatives so that I obtain
$$d{x^{\prime j}}=\frac{\partial x^{\prime j}}{\partial x^i}d{x^i}$$
Basically, the differentials make an infinitesimal d... |
I was comparing two lectures about ${\rm SU}(5)$ grand unified theory.
a lecture of Susskind
He showed how to write
$$
(5 \times 5)_{asym}=\bar{10}
$$
as
a lecture of Zee showed how to write
$$
(\bar 5 \times \bar 5)_{asym}={10}
$$
as
Other than the difference between
$$
(5 \times 5)_{asym}=\bar{10}
\text{ versus... |
There's an expectation that there aren't interacting CFT in $d>6$.
As I understand, main reason for this is due to the scaling dimension of ordinary scalar fields and Dirac fields. This lead to absence of relevant operators and then to existence only of Gaussian fixed points with free CFT.
But on other side, CFT data m... |
The number $8.9875517923(14)$ appears in Coulomb's constant. I have read that it has something to do with the uncertainty of the accuracy of the number but answers have been unclear.
Can somebody define the meaning of such notation?
|
To the question -whether the velocity of light is only constant in a space where the gravitation potential is constant- is constant, John Rennie answers that “The coordinate velocity of light can be different from $c$. The local velocity of light is still $c$.”
According to relativity theory a clock is observed to run ... |
searching for experimental values of the consumption rate of $O_2$ by tumor cells I found an article that measures the rate in the units of measure
$$\frac{mol}{cell\cdot s}.$$
The actual measurement was
$$5.5\cdot 10^{-15}\frac{mol}{cell\cdot s},$$
I precise to convert the expression in terms of $kg,\;cm,\;s$ units, b... |
Obviously red and purple are opposite on the visible light spectrum. So how do we get colors that are reddish purple? Where would they lie on the spectrum of visible light?
|
When we pluck a string, it vibrates in all possible modes of vibrations. The lowest frequency possible is the fundamental frequency and it is the most significant part of sound.
But why do the amplitude of higher harmonics decrease? Which formula is responsible?
Also, how is the energy of wave distributed among differe... |
The Toda lattice is a prime example of a lattice system that is completely integrable, in the sense that it admits a Lax pair,
https://doi.org/10.1143/PTP.51.703,
making it easy to find soliton solutions.
Generalizing this example, I'm wondering if there is a lattice system that is both frustrated (in the sense there i... |
Measuring redshift is one of the ways of analyzing distance in astronomy, since the redshift of an object is caused by the expansion of space between us and the object, the more space there is between us, the more redshift it has.
My questions are
How do you measure the redshift individually?
Doesn't the movement of t... |
Consider a PN junction diode
Now, this system will naturally form a depletion region due to diffusion and will convert into this-
Now, I wish to connect the ends of this diode with a conducting wire and resistance like this-
Thus, I expect the electric field in this space to be aligned as follows (Indicated din gree... |
I have been going through the literature on viscosity of liquids and their temperature dependence. The most commonly used forms of temperature dependencies are Arrhenius (eq. 1) and Vogel-Fulcher-Tamman law (eq. 2), as shown below
$$
\eta(T) = \eta_0 \exp\bigg[\frac{E_A}{k_B T}\bigg] \tag{1}
$$
$$
\eta(T) = \eta_0 \exp... |
First, I am a philosopher not a physicist, so apologies for limits in my understanding of quantum physics. My interest is in the philosophical implications of physics. I've just joined looking for physicists I can ask questions to, but my first question hasn't worked ... so I am going to rework it and ask it in an ext... |
A current-carrying wire has a magnetic field around it according to the Maxwell equations (Oersted's law/Biot–Savart law). When this is AC current, then also the magnetic field oscillates. The energy density in the magnetic field is given by
$$U(t)=\mu_0\frac{H(t)^2}{2} = \mu_0\frac{\tilde{H}}{2}e^{i2\omega t}\,.$$
Pow... |
Suppose if we know wavefunction $\psi(x,0)$ at an initial time $t=0$ and want to find wavefunction at later time t ; for solving such problem first we find $\phi(p,0)$ that is initial wave function in momentum space,which we find by using inverse fourier transform and then we use fourier transform to get time depende... |
The formula for resistance is
$$R=\rho\frac{\ell}{A}$$
Generally in most of the textbooks it simply written that $\ell$ is the length of the conductor and $A$ is it’s cross-sectional area. But my question is which length and area do we need to consider as a 3D body has many possible lengths and cross sectional areas. T... |
I am a high school student and have just started calculus. Part of my project involves doing this experiment where I drop a cylinder from about 10m high with a large backspin and see how far forwards it moves. Consider this diagram:
The Magnus force acts perpendicular to the velocity of the cylinder in the fluid and a... |
We know that astronauts in the ISS feel "weightless" because they are in a perpetual free fall. The earth's gravity is the only force acting upon them, and it is accelerating them towards the earth's center at the same rate as the ISS.
However, now imagine a crew in a spaceship very far from any planet, star or massive... |
Suppose we use the signature of a Riemannian manifold
$$
\eta^{\mu\nu}=\operatorname{diag}(+,+,+,+)
$$
as the starting point to describe a 4d Euclidean version of general relativity. Alternatively one may use a Wick rotation on time $t\to i \tau$ on normal general relativity to get this metric.
But instead of remaining... |
Suppose $a,b,c...=0,....,D-1$ are Lorentz indices of $SO(1,D-1)$ tangent space and consider $D$-dimensional Clifford algebra defined by the usual anticommutation relation
$$\{\Gamma^a,\Gamma^b\}=2\eta^{ab} \, .$$
Let's define the fully antisymmetric product of Gamma matrices as
$$ \Gamma^{a_1 a_2 ... a_n}=\Gamma^{[a_1}... |
As far as I understood, there are 2 Models for electric circuits that aim to simplify Maxwells Equations (by reducing the number of degrees of freedom from infinite field-values to 2 variables (voltage and current) per circuit element).
I'm however confused about how these models are obtained from Maxwells Equations:
T... |
Consider the electron interaction Hamiltonian of the form
$$H= \sum A_{ijkl} c^\dagger_{k_R,i} c^\dagger_{k_L j} c_{k_L k} c_{k_R l}$$
on $j=3/2$ states. The index $i,j,k,l$ denotes the value of $m_j \in \{ 3/2, 1/2, -1/2, -3/2\}$, and $k_R, k_L$ denotes the left/right momentum in 1D.
I am trying to find the most gener... |
The flip S is closed, find charge flown from P to Q
So I know at end behaviour of circuit, it should be just $ 15 uC$ just by applying kirchoff voltage law. Initially before switch is flipped, the equivalent capacitance is $ \frac{6}{5}$
So, the charge on each capacitor is, $ 6 \mu C $ , Now for it to the change $15... |
I know that mass of an atom can be measured using mass spectrometer, but how mass of a nucleus can be measured? simply by subtracting total electron mass of that atom? or there are other professional ways?
The point of my question is how mass of dineutron observed in 2012 could be measured?
|
Before I ask my question, I would like to clarify that this is NOT a homework question. Rather I would like to clear up an issue with my intuition about fluid statics using this problem. Firstly, I feel like there can't be any pressure on the bottom of container C as if the container is a perfect triangle with sharp ed... |
In my physics book (chapter 9 - center of mass, linear momentum and collision), it is written
Momentum should not be confused with energy. In some cases momentum is conserved but energy is definitely not.
This is a bit confusing. So I want an example of a system where momentum is conserved but not energy.
|
I understand fully where the constant comes from and why it is defined as $k=1\ \text{N}\ \text{kg}^{-1}\ \text{m}^{-1}\ \text{s}^2$
But does it have an official name?
If I were to give it a name I suppose I would maybe call it one of the following:
Constant of inertial mass
The inertia constant
Newton's constant of... |
Suppose I have a $C=1TB$ hard drive $H$, filled to the brim with English text. I'd like to compress this.
Suppose the hard drive consists (abstractly) of zeros and ones, and that the number of ones in the initial state is $n_1$, so that the number of zeros is $n_0=C-n_1$. In practice, the zeros and ones may be the orie... |
An asteroid of mass $M$ explodes into a spherical homogeneous cloud in free space. Due to energy received by the explosion the cloud expands and the expansion is spherically symmetric. At an instant when the radius of cloud is $R_0$, all the particles on the surface are observed receding radially away from the centre ... |
A collegue told me that the 2D Fourier transform of a function $g(x,y)$ consists of plane waves travelling in different directions. I don't understand this connection. In which direction do the waves point?
|
For starters let's talk about Maxwell's Equations; we know that Maxwell's Equations are invariant under Lorentz's Transformation, after all this is why all the relativity business got started. To state that a law is invariant under Lorentz's transformation is equivalent to state that the same law is true for any observ... |
In school it is generally taught that the movement of electrons between two atoms causes a chemical reaction. However, when it comes to electricity why doesn't a chemical reaction occur with the movement of electrons? (I understand that there is a chemical reaction in a battery, but even with situations like static ele... |
In Feynman's third Douglas Robb Memorial Lecture (which took place in 1976 at University of Auckland), he states that:
It's fine to approximate nuclei as a point, although they really aren't.
Quantum electrodynamics explains everything except for radioactivity and gravity.
Specifically, it explains the movement of ele... |
In Polchinski's longer derivation of the Weyl anomaly, he arrives at the result (equation 3.4.19):
$$ \ln{\frac{Z[g]}{Z[\delta]}} = \frac{a_1}{8\pi} \int d^2\sigma \int d^2\sigma' g^{1/2} R(\sigma) G(\sigma,\sigma') g^{1/2} R(\sigma') $$
where $Z[g]$ is the gauged-fixed path integral, and $G$ is a Green's function sati... |
I know that there are several posts on the same idea, and I have read most of them, but still, my questions persist. I have listed the other posts on the topic at the end of this post. All the other posts say that the electric field inside an ideal wire must be zero because:
As the potential drop across the wire is ze... |
While reading through a page on beginner Helioseismology, I occasionally came across the terms p-modes or g-modes, which I know are caused by pressure and gravity.
I wanted to know how do satellites used to study the sun detect these solar oscillations.
|
It is known that the atmosphere consists mostly of oxygen and nitrogen, with oxygen constituting about 21 % and nitrogen 78 %. Since released helium and hydrogen gases rise upwards in the atmosphere, when they are released from a container, one would naïvely think that the lighter nitrogen would rise above oxygen, and ... |
On page 43 of Manohar notes on effective field theories, he argues that since all the integrals in EFT are scale less when expanded in terms of the IR parameter, they all vanish.
To me it seems absolutely correct for the examples he's given on the same page, but if one goes to higher order terms in the IR expansion of ... |
I've heard every one say that solving problems in physics is important. In fact every textbook has a problem set at the end of a chapter. Some students even buy problem sets!.
But then I wonder do great physicists also solve problems like common students like me, or do they choose any other strategy to explore concepts... |
Suppose we have a uniform steel rod leaning against a frictionless wall in static
equilibrium. The frictional force between the lower end and the floor is less than its limiting value by a finite amount. The rod is supplied some amount of heat so that it expands. Assume that the coefficient of friction does not chang... |
When protons and neutrons interact attractively and coalesce to form an atomic nucleus, their energy in this state must be less than what it was when they are separated, so they lose mass which is then converted into energy by $E=mc^2$. Now, when electrons interact attractively with an atomic nucleus and orbit it under... |
My text book (Fundamentals of Physics by Halliday, Resnick, and Walker) mentions the following about the work done in internal energy transfers:
An initially stationary ice-skater pushes away from a railing and then slides over the ice. Her kinetic energy increases because of an external force F on her from the rail. ... |
How do you calculate the magnetic permeability of a mixture of two substances (e.g. alumina powder and boric acid) knowing the permeability of each one of them?
|
In the this paper (https://arxiv.org/abs/1203.4392), on page 2 it is said that
Since DVCS amplitude is symmetric under $s \leftrightarrow u$ channel crossing, the CFFs and $^{S}C^i_{\cdots}$ coefficients have definete symmetry properties under $\xi$ reflexion
My problem is that I don't see $u$ channel in DVCS, just t... |
In electromagnetism, all possible monochromatic electric field polarization states can be described in terms of the shape and orientation of the polarization ellipse, which maps the locus of points traced out by the electric field over a 2D plane.
There are several ways to derive the equation of the polarization ellips... |
In Griffiths Chapter 2, the harmonic oscillator the author assumes that
$$a_{-} \psi_0=0 \tag{1}$$
But we can also express this in a more general form as
$$a_{-}^n \psi = 0 \tag{2}$$
which has the eigenvalue, $E-n\hbar\omega$
$$n = ?$$
Or we could also assume that
$$\psi_0 = a^{n-1}_{-} \psi $$
which is a lot easier,
W... |
A satellite is orbiting around a planet in a circular path of radius $R$. A meteorite of mass $m$ collides with the satellite and sticks to the satellite. After collision, the satellite is seen to have gone into an orbit whose minimum distance from the planet is $R/2$. Mass of satellite is $9 m$ and that of planet is... |
I have read in my textbook that maximum work is done by gas in a reversible expansion, but I do not know the reason behind it.
Also is work done by gas maximum in reversible compression also?
|
My understanding of soliton - it is a moving pulse in a medium which does not change its structure with time. It has other properties like no interaction with other solitons (this could certainly be wrong. Please let me know if I am getting this wrong)
When reading a book on the topic, the author mentions that the NLS ... |
Cosmic strings are formed due to topological defects during symmetry breaking phase transition in early universe.
While Goldstone theorem states whenever we have continuous symmetry and it is spontaneously broken then we have scalar particles appearing in spectrum of excitation.
I'm wondering if these concept have any ... |
So basically I have an inner ring with radius $R_2$ and an outer ring with radius $R_1$, with current $I_0$ flowing through the outer ring. I am asked to evaluate the magnetic field strength at the position of the inner ring using the Biot-Savart law $$\vec{B}(\vec{r}) = \frac{\mu_0 I}{4 \pi} \int \frac{d \vec{s} \time... |
I have come to known that both longitudinal and shear strain act on a spring when it is hanging.
I can understand how longitudinal strain acts but I do not understand why shear stress/strain can act on the spring.
|
Say I am going to write down the steps of some calculations to get the final value of $s$ from an equation like this:
$$ s = s_0 + \frac12 gt^2. $$
Let us say $s_0 = 20\,\mathrm{m}$, $g = 10\,\mathrm{ms^{-2}}$, and $t = 2\,\mathrm{s}$. What is the right way to write down the units in every step so that all the formula,... |
In TASI Lectures on Emergence of Supersymmetry, Gauge Theory and String in Condensed Matter Systems there is a statement that 2d supersymmetry can can emerge from the dilute Ising model:
$$
\beta H = -J \sum_{<i,j>} \sigma_i \sigma_j - \mu \sum_i \sigma_i^2
$$
where $\sigma = ±1$ represents a site with spin up or down... |
In real life we don't have ideal spring so when doing experiments we need to take in our calculation the mass of the spring it self (the effective mass) wich made me doubt about the physical meaning of the effective mass in a spring and why we should consider it while doing measures?
|
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