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How to derive Walens Equation from Continuity Equation and Induction Equation.
Continuity Equation:
$\frac{d \rho}{dt} + \rho \nabla.v + v.\nabla\rho=0$
Induction Equation:
$\frac{dB}{dt}= -B(\nabla.v)+(B.\nabla)v-(v.\nabla)B$
Using these two Equations we should get the Walens Equation:
$\frac{D}{Dt}\left(\frac{B}{\rho... |
Basically my main question is the one in the heading of my post, because apparently "Gravitation" by Misner, Thorne and Wheeler takes it directly as true and valid (a common place for null geodesics).
We know that the rest mass of neutrinos is very very low, although we are sure it is not entirely zero. According to Wi... |
In an ideal circuit with two wires in parallel, if one path has zero resistance and another has a nonzero resistance, all of the charges will flow through the wire with zero resistance (if I understand correctly). How would the current be distributed if both wires had zero resistance?
Edit: For clarification, I'm askin... |
Looking at the formula $C = \frac{Q}{U}$ does a high capacitance mean that with a low voltage we can bring more charge onto the capacitor? How is total charge on the capacitor linked with voltage?
|
In the book "A Relativist's Toolkit" by Eric Poisson, he explains surface gravity in section 5.2.4
The equation 5.40 says
$$ (-t^\mu t_\mu)_{;\alpha} = 2 \kappa t_\alpha \tag{5.40}$$
where $t^\alpha$ is a killing vector.
And then equation 5.41 says
t$^\alpha$ $_{; \beta}$ t$^\beta$ = $\kappa$ t$^\alpha$
How to get equ... |
We have a specific requirement to concentrate a magnetic beam using small Neodymium Magnets.
Came across several older threads and within those, an older -now expired- patent:
https://patents.google.com/patent/US5929732
I am about to test this out, to see if it fulfills our requirements, but I am concerned that the arr... |
What is momentum exactly? I am confused that, is momentum a property of particle or something different.
Whenever i look for it's definition it is product of mass and velocity of a particle.
At another side, it is also said that a photon have momentum but rest mass is zero.
Then what is it exactly?
|
I have a stationary referance for $L = 0$, $L = \vec{r} \times m\vec{v}$ can be interpreted as an area of a paralelogram. The area is constant, since $base \times height = constant$.
However, is this also true, if $v$ has components in two dimensions?
The picture is more complicated now...
|
Two pictures regarding the classical limit of quantum mechanics. One says in path integral take hbar to zero then the paths constructively interference near the classical path and the paths deviate far away cancel out. The other says decoherence of a quantum system with macroscopic environment, which has untrackably ma... |
In Einstein Gravity in a Nutshell by Zee, in section IV.1 page 241, he tries to write down the action for electromagnetism and gravity in an intuitive and patchwork way,
Starting from the relativistic action in Minkowski spacetime without interaction,
\begin{equation}
S = - m \int \sqrt{-\eta_{\mu\nu} dx^\mu dx^\nu} = ... |
I ran two tests with a toy gyroscope spinning on a weighing scale that is accurate to $1$mg.
The scale was reset to zero before the tests. The gyroscope was flipped over between test $1$ and test $2$. Each test consisted of $100$ weight readings taken over roughly $20$ seconds. The readings changed rapidly so they had ... |
$\nabla \cdot \mathbf{\delta u_{perp}} = 0$ where $\mathbf{\delta u_{perp}}$ is a function of both x and y coordinates and perpendicular to z axis. Moreover, $\delta u_{perp}$ along z axis is $0$.
I need to prove that in spherical coordinates $$\mathbf{\delta u_{perp}} = \delta u (-\sin \phi, \cos \phi)$$
I was trying ... |
We learn about electric and magnetic fields and how they conform EM waves. Then we discover the photon and how there was a duality between this two ideas, sometimes radiation behaved like a wave and sometimes like a particle. Now with QED we know for sure that radiation is a particle, but exhibits a wave behabiour due ... |
In a previous question I asked, I was confused about how can you refuse determinism/realism in Bell's theorem without also refusing relativistic locality. I would like to understand where my following argument goes wrong.
Suppose that a physical theory is able to assign probabilities to events in space-time. The intere... |
Consider a container with Volume V. The container is seperated by a non-movable, impearable wall, which allows heat flow. Both subvolumes are filled with an ideal gas. We can obtain informations about the final state by using the principal of maximum entropy. Let's say the total internal energy of the system is $U$, an... |
I'm trying to do some exercises about the manipulations of the indexes. I have the tensor $X^{\mu\nu}$ represented by the following matrix
$$[X^{\mu\nu}] = [X] = \begin{pmatrix} 2 & 3 & 1 & 0 \\ 1 & 1 & 2 & 0 \\ 0 & 1 & 1 & 3 \\ 1 & 2 & 3 & 0 \end{pmatrix}$$
I have to calculate $X^{\mu}_{\phantom{a}\nu}$ so I understod... |
It has been discussed several times on this site the phrase "a tensor is something that transforms like a tensor". I'm comfortable with both the mathematical formalism and the physical applications. Even though the physical formalism can be made precise using the mathematical definition of a tensor using multilinearity... |
I am reading the paper "The quantum-to-classical transition and decoherence"
by Maximilian Schlosshauer (https://arxiv.org/abs/1404.2635).
I doubt the most basic claims in this paper.
The story is as follows: an isolated microscopic system $S$ (Hilbert space $H_S$) is put into a superposition
$\phi=\phi_1+\phi_2$ of st... |
Consider a quantum gauge theory with a holographic dual at infinite $N$ and 't Hooft coupling, in which the gauge theory is described by classical (super)gravity.
If I initialize the system in a pure state describing gravitational collapse, then a black hole will subsequently form, but it will not Hawking radiate (sinc... |
The divergenc of steady current density is zero
$\nabla \bullet \vec{J}=0 $
And, by microscopic Ohm's law $ \vec{J}=\sigma \vec{E} $
If the conductivity is uniform, we can get $\nabla \bullet \vec{J}=\sigma \nabla \bullet \vec{E}=0$.
That is, $\nabla \bullet \vec{E}$
And, by gauss's law ( $\nabla \bullet \vec{E}=\frac{... |
I'm looking at a physics textbook for A-level and in the book it states that kaons are only affected by the strong force and the electromagnetic force.
Isn't this incorrect?
Aren't kaons affected by the weak force as well?
|
At the start of QFT, studying the Klein-Gordon scalar field, it is often mentioned that the following is the definition of the scalar product in the space of the solutions:
$$\langle f _{\vec{k}}|f_{\vec{k}'}\rangle \ \dot= \ i \int d^3x f_{\vec{k}}^*(x)\overleftrightarrow{\partial}_tf_{\vec{k}'}(x)$$
My question is: w... |
I am learning QFT using the path integral approach, and I am confused about the role of the source term $J$ in the Lagrangian. I know that it is a mathematical trick that allows us to calculate $n$-point functions, which are the coefficients of the Taylor expansion of the generating functional $Z[J]$ with respect to $J... |
$$[X^{\mu\nu}] = [X] = \begin{pmatrix} 2 & 3 & 1 & 0 \\ 1 & 1 & 2 & 0 \\ 0 & 1 & 1 & 3 \\ 1 & 2 & 3 & 0 \end{pmatrix}$$
How to compute the trace of $X^{\mu \nu}$? I mean, by eye I can see it is $4$, but I don't know how to do it by writing with the metric tensor.
I calculated for example
$$X^{\mu}_{\phantom{a}\nu}= X^{... |
The paper https://doi.org/10.1039/C5SM02346G considers a compressible fluid subject to thermal fluctuations and confined between two planar rigid walls. The fluid is modeled with stochastic hydrodynamics (navier-stokes augmented with random noise) to derive spatial autocorrelation function of velocity field.
Without th... |
At onset let me make it very clear that similar questions do exist already on chemistry SE site, but none of them has a kind of answer I expect, hence I ought to start a discussion here.
As per my understanding
$\Delta H_{mix}=-RT\Sigma (\frac{\delta ln(a_{i})}{\delta ln(T)})_P,{x_{i}}$
$\Delta V_{mix}=\frac{RT}{P}\Sig... |
There are a acouple things I do not understand about the Rayleigh-Jeans calculation of the number of modes for the Blackbody problem.
The blackbody is supposed yo be a cubic box of side $a$.
I have seen in several places such as this link, that to calculate the number of modes, they solve the wave equation for the elec... |
For my undergraduate studies, I was faced with the problem of finding the equations of motion for a particle subject to a uniform electric field, in the relativistic case. I would like to follow the procedure presented in https://www.researchgate.net/publication/262474836_Relativistic_charged_particle_in_a_uniform_elec... |
I often read that a curvature in time (the rate at which clocks tick) near a massive object, is considered to be the source of Newtonian gravity.
This got me wondering, does General Relativity use the changing rate that clocks tick along the radial coordinate of a massive object to determine the rate of acceleration (g... |
A general trend of the stability of isotopes is that the higher the neutron number, the greater the stability against alpha decay because adding more neutrons weakens the electrostatic repulsion among protons (or alternatively enhances the attractive nuclear force). One good example is osmium. The energy of alpha decay... |
Eric Weinstein suggest in his interview that string theory comes from Hermann Bondi's famous paper related to negative mass in 1957 Chapel Hill Conference and that gravitoelectromagnetism and string theory came from it.
What is the role of negative mass in string theory?
|
The positive energy theorem states that the gravitational energy of an isolated system is nonnegative, and can only be zero when the system has no gravitating objects. But it assumes that the dominant energy condition holds, which assumes that the weak energy condition holds, by which the matter density observed by the... |
We know that the energy-momentum of gravity can be defined by a pseudotensor called the Landau-Lifshitz pseudotensor, which is coordinate dependent. In fact, the gravitational stress–energy will always vanish locally at any chosen point an inertial frame of reference, because the equivalence principle requires that the... |
There is a supersonic flow over a flat plate (assume inviscid--no boundary layer). Suddenly, there is a point blast occurring on the flat plate, generating a semi-spherical shock wave. For the horizontal shock component that is in the direction of the flow, it is just a normal shock-jump relation between the unshocked ... |
Treating the whole egg as the system.
On one hand: The egg was only one cell, but when it becomes a full-grown chicken, it becomes a large number of cells, highly specialized to do their own jobs. So the system becomes more ordered. Thus, $\mathrm{d}S<0$.
However, when we hatch the egg, we have to keep it at a certain ... |
In basic quantum mechanics, we define the inner product between two states $\phi$ and $\psi$ as $\phi^\dagger \psi$, where $\phi^\dagger$ is the conjugate transpose of the vector $\phi$. However in quantum field theory, we wind up making various modifications that have always seemed ad-hoc to me. For example, in the Di... |
Consider the $\phi^4$ scalar field theory.
$$
\mathcal{L} = \frac{1}{2} (\partial_\mu \phi)(\partial^\mu \phi) - \frac{1}{2} m^2 \phi^2 - \frac{\lambda}{4!} \phi^4
$$
with the partition function,
$$
Z[J] = \int [d\phi] \exp \left( iS[\phi] + i \int d^4 x J(x) \phi(x) \right)
$$
When considering diagrammatic expansion f... |
I had come across this question from a STEP paper.
I was asked to find the displacement vector r of the particle after it is given a small displacement x from its initial position of A. $\theta$ maps the angular displacement from the line $OA$ to $OP$.The radius of this hemisphere is $a$. All surfaces are smooth and f... |
In nuclear physics, while studying gamma decay (Nuclear physics, Roy and Nigam, 1st ed, pp 450) I have read that the parity of photons depends on the type of multipole radiation they represent. Means for electric type parity is $(-1)^L$. For magnetic type parity is $(-1)^{L+1}$. So, for E1 type radiation, parity is neg... |
In a deterministic classical theory we describe the positions and velocities of particles using real numbers.
In a non-deterministic classical theory we describe the positions and velocities of particles using real random variables.
In quantum theory we can describe positions and velocities of particles using elements ... |
There is a Lagrangian for a particle of mass $m$ and charge $q$
$$\mathcal{L}_1 = \mathcal{L}_k(m, \vec{v}) - q\phi + q\vec{v}\cdot\vec{A}$$
where $\mathcal{L}_k(m, \vec{v})$ is either $\frac{1}{2}m\vec{v}\cdot\vec{v}$ for classical mechanics or $-mc^2\sqrt{1-\vec{v}\cdot\vec{v}/c^2}$ for special relativity. The Euler... |
How can I show that the Hamiltonian $\hat{H}$ and time-reversal operator $\hat{T}:t \mapsto -t$ commute, i.e. that $$[\hat{H},\hat{T}] = \hat{H}\hat{T} - \hat{T}\hat{H} = 0$$ holds?
|
I have the following system:
I've applied Newton's 2nd Law to the system and I have found the normal modes proceeding as an eigenvalues and eigenvectors problem. I obtained the frequencies $\omega_1^2=0$, $\omega_2^2=\frac{k}{m}$, $\omega_3^2=\frac{2k}{M}+\frac{k}{m}$.
My problem is I don't know how to interpret my re... |
Let's take a heavy atom (since velocity of electron is high in it) and project it with relativistic velocity. So the electron revolving around the nucleus in partial particle - wave character can have velocities in direction of motion of particle, opposite to it and in between.
So these will lead to fluctuations in the... |
While solving a QFT exercise, I'm trying to calculate the Feynman propagator
$$
\underbrace{\partial_\mu \phi(x) \phi(y)} = \langle 0 \vert T { \partial_\mu \phi(x)\phi(y) } \vert 0\rangle
$$
where the derivative acts over the $x$ variable.
In this task I encountered the problem of a relative minus sign between the two... |
I came across a very interesting problem involving rotational dynamics, from the series of Cengage Physics books, which was asked in an Indian competitive exam called KVPY.
Write the constraint relations of the spool, and both masses in this figure.
Assume that the two strings of the spool have different tensions, and... |
$$E_x = \cos(wt-\beta z)$$
$$E_y = \cos(wt -\beta z + \frac{\pi}{4})$$
$E_x$ is of course in the $x$ direction and $E_y$ is in $y$ direction. Direction of propagation of EM wave is $z$.
I already know that the above EM wave is elliptically polarized, what matters is the direction of polarization:
Is it Left Handed Elli... |
Why does there need to be a particle representation of light? Doesn't light as a wave explained the observations of the photoelectric perfectly? When the frequency of light is increased, the speed of electrons also increasing. With greater frequency of light, the changing electric and corresponding magnetic fields appl... |
According to the theory, hydrostatic pressure acts in the direction normal to the surface. Accordingly, for a profile of a wall in the shape of a quarter circle (as shown in the attached diagram), the horizontal component at the deepest point is considered to be 0. However, I see calculations online suggesting that hyd... |
Assume that a drop of liquid evaporates by decrease in its surface energy, so that its temperature remains unchanged. What should be the minimum radius of the drop for this to be possible? The surface tension is $T$, density of liquid is $\rho$, and $L$ is its latent heat of vaporization.
Clearly when whatever you’re... |
I came across this question:
The question asks to determine the polarity of the ends of the electromagnet.
On applying the clock rule, the polarity of end A comes to be South while that of end B also comes out to be South. Am I doing something wrong or is the question itself wrong?
Also, I would like to know whether t... |
This is a physics bowl question. I cannot understand the two red circles. The question says '...clock has a period of 1.0s', but why the solution says T0 is 2.
In addition, what's the meaning of '43,200 cycles'?
|
I can compute Energy-momentum tensor in classical field theory using Noether's theorem and translation invariance of action, but I think I can't exactly calculate how to calculate same thing in classical mechanics , say for $$L = \frac{1}{2}mv^2 - \frac{kq^2}{r}$$
where for simplicity we can assume particle is trapped ... |
From what I already know, to calculate the expectation value/average from a probability distribution, you use the formula:
$$ \langle x \rangle \ = \int_{-\infty}^{\infty} x f(x) \,\mathrm{d}x \tag{1}$$
where $f(x)$ is the probability distribution of some variable $x$.
However, in my lecture notes, the average kinetic... |
I am little confused.Please correct me if I am wrong.
According to general relativity, there is no way to spot a difference between accelerating frame of reference and gravity.
Suppose a spacecraft is accelerated in space then we can not distinguish between the accelerating frame of reference and gravity.
My question i... |
How does vertical SHM work when the spring is moving.
In school, we've all learnt the basic vertical SHM spring attached to block setup. However, how does this same setup work in the case that the spring is moving. Imagine that someone is pulling the top of the string with a constant velocity upward. How would the bloc... |
In An Introduction to Quantum Field Theory by Peskin and Schroeder chapter 4, it has discussed about the ground state $|\Omega\rangle$ (where $|0\rangle$ is the ground state in free field theory) in interacting field theory. As (4.27) shows,
$$|\Omega\rangle = \lim_{T\rightarrow\infty(1-i\epsilon)}\left(e^{iE_0T}\langl... |
Can I write $\langle\psi\vert\alpha.p\vert\psi\rangle$ as $\langle\psi\vert p.\alpha\vert\psi\rangle$ ?
|
I am wondering whether it is possible to determine the exact colour permutation for the diffraction lines from only the following given information:
"When monochromatic red and monochromatic violet light are incident on a
diffraction grating, it is found that the fourth line observed, not counting the
undiffracted zero... |
I really need help to understand chapter 3.1.
What is the method of relaxation?
How can I use the method of relaxation to solve Laplace's equation?
How can I use the first and second uniqueness theories to solve Laplace's equation?
|
In Roger Penrose's book "Cycles of Time, An Extrordinary New View of the Universe," in chapter 1.2 "Entropy, as state counting," the author illustrates the second law of thermodynamics with an example based on mixing colors in a jar.
The author idealizes the situation by imagining a cubic box with $N×N×N$ compartments,... |
Suppose a cloud of dust of sufficient mass and density collapses to form a black hole. As this mass falls within the event horizon, to an outside observer it enters an area of infinite time dilation. (time stops) So within the mass's frame of reference it will continue to collapse into a singularity, to an outside obse... |
Following the definition in Wald's book on general relativity, in page 276 asymptotically flat spacetimes are defined using conformal isometry with conformal factor $Ω$.
Then one of the requirements is that $Ω$ will be 0 on the boundary.
Isn't it unnecessary requirement that follows from the uncompactness of the origin... |
I was looking for any lab conducted tests, or computer models of Mach reflections off of different toroids. How would shock waves propagate through asymmetrical 180° ring toroids, what kind of pressure flows would be generated?
I have a lot of different questions about what could happen so I will just ask for resources... |
In some chemistry classes I was taught the (seemingly usual) 'tale of exactly two atoms' that form bonding and anti-bonding states in the LCAO-theory (similar to this question). I've not seen the molecular orbitals mentioned since that time until now. I'm trying to learn to use pyscf, and there the author talks about m... |
The Debye-Huckel equation for electrolytes in a solution is a differential equation for the potential function in the following form:
$$ \nabla^2\phi_j + \sum^{s}_{i=1}\frac{q z_i n^{(0)}_i}{\epsilon} \exp{\left(-\frac{q z_i \phi_j}{k_{\text{B}}T}\right)} = 0, $$
where $\phi_j$ is the potential of the $j$-th ion specie... |
I saw that the moment of inertia could be calculated for bodies as the addition of the sum of their parts, so I was wondering if it could be calculated for the gyroscope that is pictured below
I was thinking that I would weigh the gyroscope, find the volume of each of its components to find the masses, and then use th... |
After some research, I figured out that all EM waves/photons are absorbed by atoms by exciting an electron from an orbital to an other. However, atoms emit only certain EM waves with specific wavelengths that we then see as color in our eye. What determines which wavelength are "completely" absorbed and how will the en... |
How could a micro black hole exist, when there is so little matter to produce the intense gravitational force required to crush matter to that extent? It takes the collapse of a supermassive star to provide that force. They make much bigger black holes. What is going to crush a little one even if it could have gravity ... |
When light travels from an optically denser to a rarer medium, it bends away from the normal and at a specific angle of incidence, the angle of refraction is ${90}^{\circ}$. When the angle of incidence is equal to the Critical angle, the refracted ray grazes the path of separation of the two media. So at this angle, th... |
It very simply states that there is an EQUAL and OPPOSITE reaction for every action, If I Punch a Wall and the Wall Punches me back, The reaction of my punch.
If the wall punches me back with the same force does that mean that is has lost some energy? But in the process of me hitting that wall, I have also punched the ... |
Empty space, is indeed not 'empty.' It is filled with the formation of particle-antiparticle pairs due to Heisenberg uncertainty. Now one of these particles escape into infinity but one of these particles also enter into the black hole. In this case, either the surface area of the black hole should remain constant(if i... |
According to Morin "Classical Mechanics" (Section 10.1, page 459), the derivative of a general vector $\vec A$ in an accelerating frame may be given as
$$\frac{d\vec A}{dt}=\frac{\delta \vec A}{\delta t}+\vec \omega\times \vec A, $$
where $\frac{\delta \vec A}{\delta t}$ denotes the rate of change of $\vec A$ measured ... |
I was wondering , is it possible to create a loop of any kind of geometry that could rotate in a non homogeneous AC magnetic field and have no net induction within the loop but only have current generated from the effect of Lorentz force on the electrons in the moving conductor ? It is achieved easily in a static magne... |
I'm currently a beginner learning classical mechanics, and I just learned about the Lagrangian formalism. I completely understand the theory behind it, but a lot of times, I'm not able to calculate the velocity correctly for the kinetic energy when doing real exercises. I also have some doubts about defining potential ... |
In Statistical Physics (Vol 5 of Landau's books) section 11, Landau derives an important relation: $\overline{\frac{\partial E(p, q;\lambda)}{\partial \lambda}} = \left(\frac{\partial E}{\partial \lambda}\right)_S$.
In his derivation, there is an important step:
He argues that averaging over statistical distribution a... |
Help me understand the differences between granulation, mesogranulation, supergranulation, and giant cells and at what depth they are created.
|
Given that the deuterium-tritium (DT) reaction has been identified as the most efficient for fusion devices, what is the ultimate balanced nuclear fusion equation?
|
As a beginner in particle physics I have a small doubt. Do we get neutrinos as a product in any process involving weak interaction? Is emission of a neutrino signature of weak interaction? OR there is a weak interaction process where neutrinos are not produced?
|
The Einstein-Hilbert Lagrangian (along with a scalar field) in FRW spacetime reads:
\begin{equation}
\mathcal{L} = - \frac{1}{8 \pi G} (3 a \dot{a}^2 - 3 k a + \Lambda a^3) + \frac{1}{2} \dot{\phi}^2 a^3 - \mathcal{V}(\phi) a^3.
\end{equation}
Let's determine the Euler-Lagrange EoM w.r.t. the variable $a$. First, the c... |
What is/are the gravitational wave observable/s that makes possible to measure the parameter/s of the equation of state of neutron stars?
|
If we heat a metal at high temperatures to melt it, its outermost electrons should also gain some energy so as to get excited to a higher state and eventually become free from the metal atom. But that doesn't happen. WHY?
|
In the olden days, $\nabla\phi$ was used to be called a covariant vector (Weinberg used this language in his book Gravitation & Cosmology). But this terminology is considered bad for several reasons and is now being slowly abandoned by physicists. In modern language, $\nabla\phi$ is called a covector, and $\partial\phi... |
Suppose I have a metric that looks like the Lobachevsky upper-half space
$$ds^2 = \frac{L^2}{z_0^2}((dz_0)^2 + \sum^d_{i=1}(dz_i)^2).$$
I now want to show that this metric is invariant under the following coordinate transformation
$$z'_\mu = \frac{z_\mu}{z^2},$$ where $z^2 = \delta^{\alpha\beta}z_\alpha z_\beta$.
To do... |
I just learned the Wilsonian renormalization group from a QFT lecture, I heard that there is another renormalization group called Bogoliubov-Shirkov renormalization group which is a true group instead of a semi-group in the case of Wilsonian RG. My question is what is Bogoliubov-Shirkov RG? What is the most important d... |
The example below is simply to provide illustration of the problem. This isn't a homework question. I'm trying to visualize the relationship between liquid and gas at the boundary and I'd appreciate general resources as much as a detailed answer:
Suppose you have an equilibrium of water and steam inside of a flash ves... |
I have been unable to find any sources online on how to do such calculations, so I am trying my luck here.
In this scenario, an object (in this case a rollercoaster) moves on a track in the form of a vertical circle. It stays in contact with the track throughout the entire loop. I am trying to find the sum of the work ... |
How can I express an arbitrary Hamiltonian w.r.t. to his Lagrangian.
Attempt:
$
H = \sum{\dot{q} p} - L
$
with
$
p = \frac{\partial L}{\partial \dot{q}}
$
and
$
\dot{p} = -\frac{\partial H}{\partial q}
$
So
$
\frac{d}{dt}\frac{\partial L}{\partial \dot{q}} =-\frac{\partial H}{\partial q}
$
We can derivate:
$
\frac{\par... |
I am learning about series LC circuit that is in resonance. It says it is when the impedance offered is minimum due to the angular frequency being at a particular value(1/√LC).People say that they are out of phase and hence cancel each other which I don't understand. What actually happens at resonant frequency that cau... |
The broad and narrow line regions (BLR and NLR) of an active galactic nucleus (AGN) are commonly described as regions of gas emitting atomic spectral lines whose width is broadened - via the Doppler effect - according to the speed with which the material is orbiting the central black hole. The gas clouds composing the ... |
I'm doing a experiment to find the relationship between the frequency of the rotating wheel and the horizontal distance travelled by the ball dropped onto it. I am manipulating the frequency of the spinning wheel and the responding variable would be the horizontal distance travelled by the ball. Assuming no friction, t... |
In the double slit experiment, one can observe which slit the electron goes through with a flash of light as the electron is scattered by a light source behind the screen.
Whenever we know which slit the electrons go though, we see no interference pattern.
But, if these measurements are done secretly by one person, and... |
Q: Is temperature directly proportional to rate of fluctuation of pressure?
--->What I mean by Oscillation/Fluctuation of Pressure
From oscillation of pressure I mean constantly increasing and decreasing the pressure by a fixed amount.
For example imagine a room with a pressure of 50 pascal, if we first increase its p... |
In gravitational wave astronomy, we usually observe $f_{GW}=2f_K$ (gravitational wave frequency twice the orbital frequency from keplerian motion). However, we also know there should be harmonics with $f=nf_0$. How could these harmonics be observed in usual GW detections?
|
Assume we have some small cylindrical particles near a specific point in a laminar flow, such that the particle Reynolds number is around unity. Neglecting mechanical interactions between particles, how many forces (except gravity and Brownian motion) are exerted from fluid on the particles and from particles on the fl... |
I'm struggling to formulate net axial and orbital momentum for >2 bodies.
The two-body problem involves a motorised disc attached to a freely-rotating one:
• disc1 is on a free axis
• disc2 is mounted to disc1 at some radius, by motor1
For simplicity 'motors' are considered intrinsic to the discs, and controllable for ... |
Something I've noticed is that when I jostle a glass of water, the water inside will start sloshing back and forth. Gradually, the water comes to rest. However, if I move the glass (i.e., translate it) in any direction, the water comes to rest much faster. Why?
|
How does anything stick to anything, for that matter?
Another example: why does perfume also stay so stubbornly on our bodies? And why do some perfumes stay longer than others on a fundamental level?
|
If we assume the ocean is sufficiently deep so that the blue light transmitted inside the water gets absorbed completely before it reaches the ocean floor and be scattered back towards the surface, and subtract the contribution of specular reflection of the blue sky, is there any blue color left? How strong is the Rayl... |
I am currently unable to see how the $T$ Matrix elements discussed in 6.1 of Sakurai's Modern Quantum mechanics 2$^\mathtt{nd}$ edition can be expressed as they are in equation (6.1.26) (see below).
My specific question is why, after combining equations \eqref{6.1.23} and \eqref{6.1.24}, the second of the 3 terms "loo... |
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