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I have a PMT that requires 1000V for operation, but SiPMs, semiconductor photodiodes require only about 30V -- what fundamental feature causes this vast difference in operation bias?
|
I already known that the potential difference when a charge moves from A to B is
But I still have confusions about what does the infinitesimal of vector $s$ refers. I mean when you change the movement of the charge from B to A, the $\Delta V$ should be opposite number of it. But if the E and S's direction is opposite,... |
I'm reading through Ashcroft & Mermin's chapter on reciprocal lattices and am confused about this sentence:
Consider a set of points R constituting a Bravais lattice, and a
plane wave, e^{i k*r}. For general k, such a plane wave will
not, of course, have the periodicity of the Bravais lattice,
I understand what a Bra... |
I'm have been reading about light propagation in periodic dielectrics. And in one part they introduce the light line. They mention that whenever the parallel and vertical components of the wave vector are bigger than the ones from the dispersion relation then there are not guided mode. In the contrary case they are gui... |
I physics books and such, I understand why they show atoms as spheres because they have the electron cloud. But why are protons, neutrons, and electrons spheres? I guess people say that because of calculations in nuclear physics, they turn out to be a sphere, but why naturally. Also, are quarks and neutrinos also spher... |
Recently in my class we studied quantization of fields and I'm brooding over
an argument/ motivation on the construction
of the quantization of the Klein-Gordon field. Recall the "classical"
Klein-Gordon field is a solution of Klein Gordon-equation Klein Gordon-equation and looks like
$$\phi(\vec{x},t) = \int c \cdot d... |
Like this:
Instead of this:
And what does the direction that the arrow look at signify?
|
How does an LED television screen emit light? My understanding is that the screen consists of many pixels, and each pixel has red, green, and blue LEDs. An electrical current runs through every red, blue, and green LED to determine each pixel color.
How does the electrical current determine each pixel color? Every pixe... |
I was looking for the average value of the relative velocity of ideal gas molecules in the kinetic theory. The following is from this article.
The vector notation is not mathematically rigorous, just take into account that.
But they say that $\vec{v_1} \cdot \vec{v_2} = 0$ on average, meaning $\vec{v_1}$ and $\vec{v_2... |
I just started to study about Mott’s Formalism and as I was going through some prerequisite material for Variable-Range Hopping Conduction I read the following paragraph,
" Theories on non-defective non-doped semiconductors show that the Fermi level is positioned around mid-gap to obey the condition of charge neutralit... |
In the 'electron in a box' model, is the standing wave description of the electrons same as the electron's wavefunction? If not, what is the relationship between those two? How is the wavefunction related to other concepts like De Broglie wavelength and standing wave model of an electron?
I'm so confused that I cannot ... |
I have been studying this lecture from Scott Aaronson: https://www.scottaaronson.com/democritus/lec9.html
In the section "Mixed states", he says you can find the combined state by using the density matrix, and summing. I understand that part.
Further down, in the section "Real vs Complex Numbers", he says if you know t... |
Based on the magnitude of time dilation around the sun and the change in time dilation based on the radius from the sun.
Is there an easy way to calculate the Perihelion of Mercury?
|
If an electron receives the right photon, it gets excited and emits another photon or multiple less energetic photons when it returns to ground state. Therefore energy is conserved.
However, if an electron receives enough energy (referred to as work function) to be kicked out of the orbitals, it can not return to groun... |
It is known that gravitational waves travel at the speed of light, and are themselves subject to lensing by gravity. My question is, how then do the waves escape the black hole they came from in the first place?
|
Scenario, I want to play a game with a group of students as a teacher, I ask two teachers to help.
The students are from the central classroom, going to room A and room B where the teachers there asks the students question 1 or 2. So A1, A2 are the possible questions to ask students who are in room A, B1, B2 are the po... |
There is a particle with spin of $j=\frac{1}{2}$, and it is on a state $|j,m_z=\frac{1}{2}\rangle$. What is the probability the state particle will be $|j,m_x=\frac{1}{2}\rangle$?
Well, of course the probability of being in the state $|\alpha\rangle $ if it is on the state $|\beta\rangle$ is $P=|\langle \alpha|\beta\... |
This might be a very trivial question, but in condensed matter or many body physics, often one is dealing with some Hamiltonian and main goal is to find, or describe the physics of, the ground state of this Hamiltonian.
Why is everybody so interested in the ground state?
|
The above quote is often attributed to Einstein, though according to QI it does not originate from him. My question is: isn't the quote completely untrue, as quantum mechanics & nuclear decay completely disprove it, as in both there are examples where doing the same action can lead to completely different outcomes.
|
I want to show the formula $(\frac{\partial\mu}{\partial N})_{V,T} = -\frac{V^2}{N^2}(\frac{\partial p}{\partial V})_{N,T} $ on a grand canonical ensemble case. But how can I prove this?
I know that the relation $d(PV) = SdT+Nd\mu+pdV $ holds for grand canonical ensemble but I could not go any further.
|
A resistor of unknown resistance can be found by constructing a series circuit, containing a power supply, ammeter and voltmeter across the unknown resistor, then Resistance=Voltage/Current. In a high school exam question, it says by using a potentiometer in the circuit, a more accurate value of the unknown resistance ... |
Calculate the refractive index of gold at a wavelength of $632.8$ nm using the simplified Drude model for metals.
Assume linearly polarized light at $45$° that is incident at an angle of $80$° on a golden surface.
Find the Jones vector for the polarization of the reflected light.
The final answer needs to be of the for... |
The action for a general relativistic particle should be:
$$S=\int d\tau\int d^3x \sqrt{-g} g^{\mu\nu}\dfrac{dx^\mu}{d\tau} \dfrac{dx^\nu}{d\tau} \,\delta^3(x-y)$$
where $g_{\mu\nu}$ is the 4-metric. How to derive from this action the ADM form of the Hamiltonian?
The momenta should be $\pi^\mu=\sqrt{-g} \dfrac{dx^\mu}{... |
If we have an action of the form:
$$ S^{(0)} =\int d^Dx\sqrt{-G}\left(R+\alpha (\partial \phi)^2 + \frac{1}{6} e^{2 \alpha \phi}H_{mnp}H^{mnp}\right).$$
where $H_{mnp}=\partial_m B_{np}+\partial_n B_{pm}+\partial_p B_{mn}$ , $B_{mn}$ is an anti-symmetric tensor and $\alpha= \frac{4}{D-2}$ . This is the effective action... |
I was wondering whether the divergence of a vector field which is defined by a (positive) point charge is positive, zero, or negative everywhere. It is assumed that the charge is at $(0,0,0)$. Intuitively, I would think that it would be negative since the field gets weaker the further you get from the charge, which wou... |
Multiple dimensions of space makes sense.
We can understand multiple dimensions of space by lines ,planes,spaces etc.
But what does a 2-D time,3-D time etc means.
Visualizing time as a line makes sense ,where forward means future,backwards means past and present means the point we are in right now.
But a 2-D or 3-D tim... |
Hypothesis
During an earlier epoch the universe was filled with hot dense plasma. During this time the dominant structure forming force was electromagnetic. As plasma is prone to self organizing the remnant of this epoch can be seen in the largest scale structures in the universe namely filaments. As the universe cools... |
I was answering this question and even tho i know intuitively that the radial component of the eletric field will cancel out by simmetry, i could not get that in the integral calculation. I´m asking if you can help me figure out what mistake i did in the exercise. Thank you!
|
Because the resolution of an objective is limited by the diffraction of its circular aperture, I don't understand why an infinite lens can not have an infinitely good resolution power.
People use Abbe relation to compute the minimum resolvable distance $p_m$ of an objective as a function of its numerical aperture NA:
$... |
I was just looking at the history of the Uncertainy principle. It is written here that
In his celebrated $1927$ paper, "Über den anschaulichen Inhalt der quantentheoretischen Kinematik und Mechanik" ("On the Perceptual Content of Quantum Theoretical Kinematics and Mechanics"), Heisenberg established this expression as... |
This is the course content for a waves and optics course that I am currently taking:
Oscillations: Review of simple harmonic motion and damped oscillations, coupled oscillators and normal modes.(4)
Waves: wave equation, superposition of waves with same and different frequency, Lissajous figures, standing waves, dispers... |
There is no standard light clock. Anyone can design a light clock of his/her own choice. This means it can be normal, contracted, and dilated as well but of no meaning. Some of the clocks are shown in the figure. The one with theta = 45 degrees is an anti-time dilation light clock.
https://i.postimg.cc/fWYVpF2v/IMG-219... |
Consider the potential distribution across a PN junction. The difference in the Fermi levels between the differently doped semiconductors leads to a 'built-in' voltage across the semiconductor junction.
What happens to the potential distribution if we short-circuit the device i.e. connect the two contacts together?
Giv... |
I want to become an aerospace engineer and use the physics of fluid dynamics and thermodynamics. I'm going into 9th grade soon and finished algebra 2 in 8th grade. What classes should I take?
Someone I was talking to said differential calculus, vector algebra, rotational dynamics - advanced mechanics and regular Newton... |
It is commonly stated that the low energy theory of some non-relativistic fermion band structure with a linear dispersion $E = vk$ implies the
low energy effective theory is a relativistic fermion theory.
there is an emergent Lorentz symmetry at or near the node
Of course $E = vk$ is necessary condition, but it do... |
when looking at Shockley's ideal diode equation I wonder what "meaning" the temperature has in there?
If I assume $$I(T) = I_0 \left[\exp \left( \frac{U}{k_BT/q}\right)-1 \right]$$
and vary the temperature (250K, 300K, 350K -> blue, yellow, red) I'll see exactly the opposite trend of what I would've expected. I expect ... |
As we all know, atomic clocks are being used to measure time and the GPS system.
But I was wondering based on what was the first atomic clock calibrated and how accurate this calibration was based on our standards nowadays?
|
I had a quarrel with a friend of mine regarding external/internal forces. He insists that an external force cannot become internal when we change the reference frame, whereas I claim otherwise. For a better perception, assume that a tiny positive charge is detached from the positive plate and set in motion uniformly to... |
Suppose I have a prepared a fluid at conditions where liquid and vapor coexist at a common temperature. What does the interface between the two phases look like microscopically? If I scan an imaginary microscope from the liquid to the vapor, should I expect to see a gradual transition from higher density to lower densi... |
I have a doubt regarding pressure in a fluid. Going through a few examples and questions on Bernoulli's equation, one thing which is common is to choose a suitable point where we know the pressure, and maybe the velocity and then calculate the unknowns.
For example in the velocity of efflux we take the pressure on the ... |
In electrostatics, we have that the electric field of a charged wire is given by,
$$ E(r)=-\frac{\lambda}{r}, $$
where $\lambda$ is the wire charge density.
My question is; what about the constants in the potential? I know that the potential which gives this field can be written as
$$ V(r)=\lambda\log(r), $$
however, t... |
The geometric quantization can be considered as an approach the formalize the way of
associating a quantum theory corresponding to a given classical theory.
Suppose we start with a sympetic manifold $(M,w)$ with symplectic form
$w$. The geometric quantization procedure falls into the following
three steps: prequantiza... |
If the following list of functions defined on $x \in [0,L] \,$
$$\phi_n(x) \equiv \sqrt{\frac{2}{L}}\sin\left(\frac{n\pi}{L}x\right)$$ where $n$ is positive integer and the functions are zero at the boundary points.
The question is to show that the following identity
$$-\frac{h^2}{2m}\frac{\partial^2\phi_n(x)}{\partial... |
Assume $\mathbf F$ is a non-conservative force and it's the unique force acting on a particle, to simplify.
Elementary work done by $\mathbf F$ ($\delta W = \mathbf F \cdot \rm d \mathbf r $) is an inexact differential, as there's no function $U$ such that $\mathbf F \cdot {\rm d} \mathbf r = {\rm d} U = \frac{\partial... |
I have already worked out the expectation value of the the product in the opposite order $\langle x\,p_x\rangle$. I'm now trying to work out the expectation value $\langle p_x \, x\rangle$. I've been trying to work it out from
$$
\int \psi^* \left( -i\hbar\, \frac{\partial}{\partial x}\right)x \,\psi\, dx
$$
I can't se... |
In deriving Planck's blackbody formula, the number density of normal modes (per unit frequency$^\dagger$) is found, given by
$$
N(\omega)=\frac{V}{\pi^2c^3}\omega^2,
$$
where $V$ is the volume of the blackbody. Then the average energy of a mode of frequency $\omega$ is calculated using Planck's quantization that energy... |
I have a doubt regarding Kirchhoff's law of thermal radiation. From what I found online Kirchhoff's law says that the monochromatic absorptance equals emittance in thermodynamic equilibrium, in a particular direction. If the surface is diffuse then the direction does not matter.
My doubt is this:
Suppose we have two di... |
Usually we can shift the energy $E$ by any amount $\delta$ to redefine the lowest energy as
$$
E + \delta.
$$
However, in supersymmetry, there is a precise $E=0$ must be true, so that the supercharge $Q$ annihilates some state $|\psi_{min}\rangle$ to give the minimal energy
$$
Q |\psi_{min}\rangle =0
$$
and also
$$
H|\... |
I am reading chapter 7 in the 3rd edition of Goldstein's Classical mechanics textbook and the expression for the Lorentz force is confusing me. I cannot scan it so I am just going to write it out verbatim and formulate my question afterwards. Here is the extract of page 298 from the text:
In terms of $\phi$ and $\math... |
I am computer scientist and not a physicist, but I really like physics
One question popped into my mind recently about gravity. General theory of relativity describes gravity not as a force but as a curvature of space-time. So if gravity is not a force but just illusion caused by curvature of space-time then why do we ... |
Background
According to an article from Physics Today, ice is slippery because there is a “liquid or liquid-like layer” on its surface.
There are 3 mechanisms that can cause this layer to exist, each playing a role that depends on the temperature, and other factors. These mechanisms are:
Pressure melting (the least do... |
Can a pendulum reach the vertical ($\theta = 180^°$) in a train that brakes hard? I think the answer is yes but I don't see how to show that. I used the frame of reference of the train but I found that $W(\vec{f_{ie}})=0$ where $\vec{f_{ie}}=m\vec{a}$ (initially the train is at constant speed, so the force is perpendic... |
First of all, I am new in this field and therefore if I ask a silly question please forgive me.
I have a gas-cell (say 3$\times$3$\times$3 mm$^3$ volume) filled with a N$_2$ gas. The number density is known. Now I want to shine a pulsed laser light on this volume element (gas cell) with 20ns, 800nm, and energy per puls... |
When a body is thrown up with velocity $v$ and there is air resistance $F=-kv$. Then while writing acceleration $a=\frac{\mathrm{d}v}{\mathrm{d}t}= -\frac{mg+kv}{m}$ , the minus sign is put due to sign convention. But $\mathrm{d}v$ in itself is negative. So why do we put a negative sign also?
|
I am following Richard Martin on interacting electrons. For independent electrons at zero temperature he finds that the time-ordered Green's function is given by
$$
G(x_1,x_2;\omega) = \sum_{l} \frac{\psi_l(x_1) \psi^*(x_2)}{\omega - \varepsilon_l + i \eta \, \mathrm{sgn}(\varepsilon_l - \mu) }.$$
You could in principl... |
I don't understand few steps in my book for an example.
Firstly, I have this $$f(y,y',x) = \sqrt{1+y'^2}$$
Euler-Lagrange equation $$\frac{\partial f}{\partial y} - \frac{d}{dx}\frac{\partial f}{\partial y'}=0$$
Then, $\frac{\partial f}{\partial y} = 0$ which means $\frac{\partial f}{\partial y'}$ is a constant.
$$\fr... |
http://www.stat.physik.uni-potsdam.de/~pikovsky/teaching/stud_seminar/Wigner_function.pdf
From the Appendix in the above PDF (page 945), below equation (A3) the following expressions are given:
$$
u = p' - p''
$$
$$
v = p' + p''
$$
$$
dudv = 2dp'dp'',
$$
where $p'$ and $p''$ are momenta. When I try to calculate $dudv$... |
Consider the dumbbell graph decorated with propagator $P$ one the edges and with integration variables $x$ and $y$ on the vertices.
We associate to it the following integral:
$$ I = \int_{x,y} P(x,x)P(x,y)P(y,y). $$
Does $I$ appear in BRST gauge fixed perturbative Chern-Simons theory (for some gauge group, which one?)... |
There are statements about Goldstone fermions, or goldstino, seem confusing to me.
(1) Goldstone boson requires a continuous symmetry spontaneously broken. Does Goldstone fermion imply continuous SUSY spontaneously broken? But boson B and fermion F Hilbert space can be finite dimensional and discrete. The number of SUS... |
Answers to Where do gravitational field lines go exactly? We know where they start, but explain that for Newtonian gravity they go to infinity.
In a simple Newtonian gravity exercise there is no "speed of gravity" consideration. At any moment we can calculate the potential field from integrating $-G \rho(r) / r$ where ... |
From what it was written, the calculation of effective mass in semiconductor had two different types, one is effective mass for density of states, through geometrical mean, the other one was the effective mass for conductivity, through harmonic mean.
Question 1:
Why it was that for density of states, the calculation o... |
In my understanding, electric power we use at home is produced by generator in the same way we watch a live streaming TV show. If the generator stops spinning, we don't get electricity. The electricity is not saved in a huge storage and then delivered to us.
Assuming there is no loss during transmission, the nuclear fu... |
Can you explain using the fact that electric field and magnetic field are perpendicular each other?
I wanna visualize the field and electric current image in my head.
I searched this and read some answers, but it was about energy conservation. this kind of method of explanation is indirect explanation. I want direct ex... |
I recognize that the oscilloscope is a very useful instrument. But I would like to know what are the reasons why the oscilloscope is such a useful instrument in day-to-day scientific work. I would like to think that these reasons will be the same ones that motivated the design and creation of the first oscilloscopes.
I... |
In, say, a quantum field theory of a single scalar field $\phi$, it is common to write the identity as ${\bf 1}=\int{\cal D}\phi\, |\phi\rangle\langle \phi|$, a useful thing to do in various path integral manipulations. Here, the path integral is over configurations of $\phi$ on some particular time slice. For instan... |
I'm wrestling with the problem of a car accelerating from rest whose engine is outputting a torque that would result in a force at the point of contact between the wheel and the ground that is greater than the force of static friction. From my understanding, the wheel would slip, and if the torque remains the same, wou... |
What precisely and mathematically does it mean to have $W$ bosons carry electric charges?
We know from Wikipedia that experiments say that $W$ bosons carry electric charges:
$W^\pm$ carry $+$ and $-$ of electric charges.
However, the gauge fields do not sit at any representation of the gauge group, but the gauge fiel... |
Why are the five d-orbitals denoted by the symbols $d_{z^2}, d_{x^2-y^2}, d_{xy}, d_{yz}$ and $d_{zx}$? Does it have to do with the wavefunctions of d-orbitals? The symbols for the f-orbitals are even stranger.
|
Verifying formula for Work;
$$W = \int \vec{F} \cdot d\vec{x} \quad(i)$$
Let us consider a very simple scenario; I will solve first by simple Maths and then by calculus.
Scenario 1: (Force vector is always $5\vec{i} N$) [Solving by simple maths,]
A block of mass 2kg is initially at origin($\vec{x}=0\vec{i}$) is displa... |
Gravitational potential energy is defined in the textbook as the amount of work done in bringing a mass from infinity to that point in gravitational field without producing acceleration.
What does 'without producing acceleration' imply?
|
The Fokker-Planck equation for a diffusing particle in the potential $V$ is
$$\partial_t p = -\nabla\cdot (p \nabla V) + D \Delta p.\tag{1}$$
In the literature, one often sees this formulation used with non-differentiable and infinite-valued potentials, in particular the "infinite square well" potential $$V(x)=\begin... |
According to my professor, Torque is like the connection of force in the angular world. But, we know that most quantities such as angular acceleration, angular velocity, etc. are defined as something divided by $r$. So then why is torque defined as the product of $r$ and $F$, when intuitively it should be $F/r$?
|
My question is similar to this one but it is for sure not a duplicate of it. I basically want to see the same scenario in terms of energy transfer.
What I know for sure is that bodies under collision get deformed and there is nothing like a perfectly rigid body.
Now if we consider a perfectly elastic collision betwee... |
The Poincare transformation reads,
$$x\rightarrow x^\prime=\Lambda x +a $$
The scalar product is preserved under Lorentz transformation. However I do not see how it is preserved under the more general Poincare transformation,
\begin{align}
x^T\eta x\rightarrow {x^{\prime}}^T\eta x^{\prime}&=\left(\Lambda x +a\right)^T\... |
In a recent popular video by Veritasium it is claimed that no one has devised an experiment that measures the one-way speed of light, and that in theory a directional difference in the speed of light is possible.
I can understand that it's difficult to design experiments to test this on earth, but does cosmology not pr... |
I think physicists believe space-time to be continuous. Is it still just a belief though? If we travel from one point to another point along the sides of a right triangle, and then try it again by using the diagonal, then we can confirm that spacetime is not quantised by confirming that the time taken obeys the Pythago... |
From what I understand, Einstein tried to introduce real but hidden variables to remove the apparent non-local nature of quantum entanglement, but Bell's inequality showed local realism isn't possible.
I have read physicists believe in locality than hidden variables because experiments and intuition say so, thus I have... |
Local and memoryless are easily defined in quantized space and time:
Local: What happens from one time step to the next in one "cell" of quantized space is only influenced by the state of neighboring cells.
Memoryless: The state in the next time step is only influenced by the state in the previous time step (not earlie... |
I saw this number on Wikipedia and other videos, but the calculation part is no where to be seen. Can someone explain how this value is calculated?
|
Spatial part of the ground state energy eigenfunction for a quantum particle confined
to one dimension with a harmonic oscillator potential energy is given by:
$u_0(x)=(\frac{m\omega}{\pi \hbar})^{1/4} \exp(- \frac{m\omega }{2\hbar} x^2)$
If we have the same particle in the same system at $t=0$ given by:
$\psi(x,0)=(\f... |
A spacecraft is placed in orbit around Saturn so that it is
Saturn-stationary (the Saturn equivalent of geostationary – the
spacecraft is always over the same point on Saturn’s surface on the
equator).
Information the question provided:
mass of saturn = $5.68\times 10^{26} kg$
mass of spacecraft = $2.0 \times 10^{3}k... |
Once in a book ( I think title was Mathematical Physics, no idea who the author was) saw the proof of instability of planetary orbits in 4 dimensions, cant remember the details of derivations only the final conclusion of the result.
Been trying to do something similar myself, but still with no success, how ever pondere... |
I am new to the world of electricity and magnetism. And still learning the basics of it. As I was studying about transfer of electrons I got the following doubts
(1) Can I feel the electrons which pass between two objects?
(2) I am unable to convince myself with the thought that why would electrons flow between two obj... |
What is Brane Inflation and how does it describe inflation process? Can it be eternal?
|
TLDR: I want to rotate a stiffness tensor in Voigt notation, but my rotation matrix does not match a reference solution. The values are the same but some signs are reversed. I don't see what I am overlooking. Any help is appreciated!
In detail: I start with a basic rotation matrix
$$
Q_{x} =
\begin{bmatrix}1 &... |
I am reading kleppner,it said when change in a vector is always perpendicular to itself then vector's magnitude doesn't change only direction changes.
I'm having a contradiction with my thought process here's how....
In limit Δt tends to zero if vectors change is perpendicular to itself then there would be a infinitesi... |
Why is it that when you break a brick it hurts less than when you don't break the brick?
Consider the brick has a maximum force it can endure $F_\text{max}$. If you hit the brick and it doesn't break the impact force is less than $F_\text{max}$, and you feel a reactionary force equal to the impact force you exerted on ... |
I am a high school student, and I am very confused about sound waves. My teacher taught me that sound is a pressure wave, i.e the atmospheric pressure varies during the propagation of sound, and all the medium particles perform simple harmonic motion (if amplitude is not so high).
But my confusion is that if all the pa... |
The Sunlight is an electromagnetic radiation.
Is it known what is the origin of this radiation? Can it be adequately described by classical electrodynamics (Maxwell's equations) as a motion of electric charges in the Sun? Is it necessary to take into account quantum effects described by quantum electrodynamics? Or is i... |
Consider two spheres A and B of similar mass and radius kept on a smooth surface. If I give an impulse 'J' to one of them along its centre of mass axis, it would only translate and not rotate.
Its velocity Va just after collision would be J/m.
So, its kinetic energy = 1/2 m Va^2
However if I apply the same impulse 'J' ... |
I'm going through a question in Finn's thermal physics,
I can't figure out part (c). I understand there will be some pressure change which will cause a certain portion of the gas to condense to water. I can't find a way to calculate that mass. I've tried long-winded methods by equating pressures of the gas to the mer... |
As I know that the definition of the CMB rest frame is the comoving frame of the plasma emitting CMB. And the anisotropy of CMB is due to the velocity difference between the earth frame and the CMB frame. But I have read a textbook mentioning that observers are at rest with the current CMB proper frame and a star at $z... |
In the following situation:
A 700 g block is released from rest at height h 0 above a vertical
spring with spring constant k = 400 N/m and negligible mass. The block
sticks to the spring and momentarily stops after compressing the
spring 19.0 cm. How much work is done (a) by the block on the spring
and (b) by the spri... |
If we observe any textbook they say that molecules form band spectrum. But a H2 molecule is just 2 H atoms and both form line spectra but somehow combination of 2 H atoms formed band spectrum. Because if even 2 H atoms are present they both absorb the same wavelengths and then this implies they should form line spectra... |
I am reading this paper The Bardeen model as a nonlinear magnetic monopole by Eloy Ayón-Beato Alberto Garcı́a. A the end where the authors prove the that the weak energy condition is satisfied, they say that the vector
$$E_\lambda = F_{\lambda\mu}X^\mu$$
is space like because it is by definition perpendicular to the ti... |
I'm reading this famous paper about the classification of quantum phases, and I'm wondering about the physical meaning of the definition of phases the authors use.
They say that two Hamiltonians $H_0$ and $H_1$ are in the same phase if there exists a continuous path $\gamma\mapsto H_\gamma$ of gapped Hamiltonians inter... |
If we have the complex scalar
$\langle f|\Omega|g\rangle$ as in equation (2.73) of these course notes (where $\Omega$ is Hermitian), and want to evaluate it in the position basis, I would proceed as follows:
$\langle f|\Omega|g\rangle =\iint dx \ dy\langle f|y\rangle \langle y|\Omega|x\rangle \langle x|g\rangle =\i... |
I know that effective mass can be measured experimentally by various techniques like cyclotron resonance, ARPES, or specific heat measurement at low temperatures. I want to know what is the difference between these effective masses or are they all the same? How are these effective masses related to the Inertial effecti... |
By work-energy theorem: total work done on a mass equals the total change in kinetic energy. So, is there any case where only non-conservative forces are acting on a mass and this causes total change in kinetic energy?
If yes please give an example.
Edit:
I mean,
Wnc = K2-K1.
|
In quantum mechanics, would the position operator $\mathbf{x}$ commute with the operator for a rotation in $SO(3)$ of the form:
$$ \frac{i}{h} \mathbf{\omega} \cdot \mathbf{L} ?$$
Where $\omega$ is the angle rotated about the axis and $\mathbf{L}$ is the angular momentum.
|
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