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I'm struggling with this doubt.
Here it is....
There is a infinitely long current carrying wire. A charged particle is projected with a velocity v parallel to direction of flow of current... then it get deviated due to magnetic force qvB
Where q is charge of the particle
v is velocity of particle
B is field due to wire... |
In David Tong's lecture notes on Gauge Theory, in the section on 'Quantising the Colour Degree of Freedom', the following action is discussed,
$$
S_{w}=\int d \tau i w^{\dagger} \frac{d w}{d t}+\lambda\left(w^{\dagger} w-\kappa\right)+w^{\dagger} A(x(\tau)) w.\tag{2.17}
$$
here, the complex vector $w$ is the internal, ... |
I want to know that does $F^{a}[A_{\mu}] = 0$ condition used in Faddeev-Popov Quantization has unique solution $A_{\mu}$ or is it $F^{a}[A^{\theta}_{\mu}] = 0$ should have unique $\theta$ as solution where $A^{\theta}_{\mu}$ is gauge transformed $A_{\mu}$ with parameter $\theta^{a}(x)$ (but then won't $\theta = 0$ is a... |
If we sit in the satellite's frame of reference(which is non-inertial because the satellite is accelerating) the pendulum's bob will feel a pseudo force just opposite to the gravitational force being applied on the bob, this will result into bob feeling no acceleration due to gravity which makes the time period infinit... |
It is my understanding that there are many interpretations of observation/measurement in Quantum Mechanics (I am only familiar with the Copenhagen one).
The Schrodinger's Cat experiment forms a paradigm in terms of understanding the state of a quantum system before its observation. Sometimes the analogy is taken too fa... |
I am reading Schwartz's Quantum Field Theory textbook. In chapter 3, Schwartz first defines the conserved current for a symmetry $\phi \rightarrow \phi + \delta \phi$ that depends on a parameter $\alpha$ as $$ J_\mu = \frac{\partial L}{\partial (\partial_\mu \phi_n)} \frac{\delta \phi_n}{\delta \alpha}. $$
However, Sch... |
I can't find this, but i've seen that GR is the only possible theory of gravity if you assume causality and principle of equivalence?
|
In the following system, the disc is vinculated to move along the y axis and the point P to move along the x axis. There is no friction. I need to determine the potential energy so that I can later apply the Lagrangian formalism. The lagrangian coordinates are x and y as depicted in the figure. In the provided solutio... |
I was thinking about a problem with a simple wooden drum , constructed but just a membrane and a wooden circular part .Let's say the mebrane is streched by a constant tension $T$ and it has a density $\rho$ We know that the points of the perimeter are fixed .
The motion of the membrane can be described by: $T(\frac{d^... |
If you have an object moving at constant velocity on a planet with no atmosphere and friction then the force of gravity is greater then the normal force. Wouldn't that mean the object would be falling to the center of the planet.
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I don't know much about Einstein field equations, but I'm wondering are there any relationships between the Einstein field equation (or the vacuum field equation) and the Mass-Energy equation $E=mc^2$? Or they are describing different objects so should be considered separately?
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So, metallic bond doesn't form between two atoms, it forms when there are a large number of atoms.
However, the establishment of metallic bond was statistical, thus there might be a time where metallic bond was weak when sufficient but not enough atoms were presented.
Thus, would a pack of MN atoms has stronger metalli... |
Firstly a battery causes an accumulation of electrons in the negative terminal right? Hence the positive terminal is relatively positive and so an electric field is produced.
This electric field will cause electrons to move from the negative terminal to the positive terminal and on doing so the electrical potential wou... |
I have a simulation where a bunch of particles are moving. Every time step I fit a gaussian (through non-linear least squares) to the distribution of speeds. Here I end up with a temperature $T_i$ and a variance $\sigma_i ^2$ on this parameter.
I do this for every time step during a period of time, i.e. I end up with ... |
Consider the following derivation:
$$
\operatorname{Tr}_{\mathcal{H}_{B}}(\hat{O})=\sum_{K}\langle\tilde{B}_{K}|\hat{O}| \tilde{B}_{K}\rangle=\sum_{K} \sum_{i} \sum_{I} \sum_{j} \sum_{J}\langle i, I|\hat{O}| j, J\rangle|B_{i}\rangle\langle B_{j}| \otimes\langle\tilde{B}_{K} \mid \tilde{B}_{I}\rangle\langle\tilde{B}_{J}... |
I'm trying to understand how a Fire Piston works, in the context of the First Law of Thermodynamics.
The First Law states that
$$ \Delta U = q + w = 0 \text{ (for an isolated system)} $$
Where "isolated" means that there is no exchange of matter or energy with the surroundings.
We can construct an isolated composite s... |
For the sake of simplicity, say we given that $a = 6t$ and that we must find the velocity as a function of time. We would set up the following integral:
$$\displaystyle \int_{v(t_0)}^{v(t)}dv = \int_{t_0}^t 6t\,dt$$
Having $t$ in the bounds of integration and also in the integrand seems weird to me. Is this the best wa... |
Before opening the box, the observer does not know if the cat is alive or dead, however, a camera placed internally "knows" all the time, which is really happening.
Does this camera cancel the result of the experiment, even if it is not consulted?
EDITING:
I made this edition just to clarify my doubts.
The camera could... |
I've read in Mermin (https://doi.org/10.1063/1.2810588) that the operators $\hat{\sigma}_{y1} \hat{\sigma}_{x2} \hat{\sigma}_{x3}$, $\hat{\sigma}_{x1} \hat{\sigma}_{y2} \hat{\sigma}_{x3}$ and $\hat{\sigma}_{x1} \hat{\sigma}_{x2} \hat{\sigma}_{y3}$ all commute as "the product of any two of them differs from the product ... |
I have simulated a high penentration metasurface design and want to fabricate it. |E|^2 decays above the metasurface with very long ~ 1um decay length.
What would be a good experimental way to measure the penetration length?
|
Many sources that say in free broadening of a Gaussian wavepacket, the momentum uncertainty (I think defined in terms of the range of 'significant' momentum amplitudes) is time invariant even as the Gaussian wavepackets broadens in position.
I'm trying to reconcile how this is consistent with the uncertainty principle.... |
It stands to reason if gravity changes the color of light then the color will be affected by gravitational waves. My question is, when the waves pass, will the color change be permanent or will the light always return to its original color? It seems to me that if gravitational waves have energy and momentum and can im... |
One of the things I am struggling with in working with electrostatics is in situations where a charge is surrounded by a concentric sphere, and Gauss's Law must be applied.
Like if there is a metal sphere with charge $Q$ on the outside of it, with a radius $r_1$
I know that Gauss's Law
$\oint\limits_SE \cdot d{\textbf ... |
Let's say we have two point charges q1 and q2 both of which are positive, according to Newton's third law the force one exerts on the othe is equal to the force the other exerts on the first. Therefore
$F_1 = q_1 E_2 $
$F_2 = q_2 E_1$
$F_1= F_2$
Therefore:
$q_1 E_2 = q_2 E_1$
Now let's say that we have two concentric s... |
Let's say that I held a hot object with a warm cloth. It instantly feels less hot and only warm to the touch. This is because the cloth is an insulator and doesn't allow as large a heat transfer as if I held the object with my bare hands.
However, I presume that eventually the cloth will reach the same temperature as t... |
The gravitational force on a body due to another body is $\frac{Gmm'}{R^2}$ where the mass of the respective bodies are $m$ and $m'$
So the acceleration of one body (say mass $m$) be $\frac{F}{m}$ which is $\frac{Gm'}{R^2}$. Therefore, acceleration is function of separation of the two bodies meaning acceleration keeps... |
Recently I made this video. It can be seen and heard that the remote control (MTLogic) of our TV doesn't work when I place an object between it and the TV. This is the remote control:
It's obvious the signal doesn't reach the TV when the object is present. How can this be explained? I tried to do this at every angle (... |
I've come across a reaction shown as $ ^7\text{Li}(\alpha,\alpha^\prime)^7\text{Li}^*$. I understand that the asterisk indicates that the final $ ^7\text{Li}$ is in an excited state, but what about the prime symbol on the $\alpha$? Does it simply indicate the incident $\alpha$ after the interaction? If so, would it b... |
I need to find the quadrupole expression from the dipole expression. I know that the dipole expression is
$$V(\vec{r}) = \frac{1}{4\pi\epsilon_0}\frac{\vec{p}\cdot (\vec{r} - \vec{r}^\prime)}{|\vec{r} - \vec{r}^\prime|^3} $$
Now, I wanna find the quadrupole expression from the above expression. I tried to do the follow... |
I have an spherical ballon filled with an ideal gas such that the difference of pressure between the interior $(P)$ and the exterior $(P_0)$ is proportional to the radius of the balloon:
$$P-P_0 = \xi r$$
Where $\xi$ is a constant associated to the characteristics of the balloon. I can assume that the external pressure... |
A follow-up question of the subspaces of 4-electrons: assume the magnetization of the system is conserved (the number of total spin-up $(\uparrow)$ particles is conserved), say 1, for example. Then the eigenvalue of M is 1. I'm wondering if I want to write the total Hamiltonian matrix (it should be 4 by 4 in this case)... |
At 9:07 in the latest Veritasium video, we see a map showing elevated levels of iodine-131 in the United States. The big band through the mid-west makes perfect sense to me; nuclear weapons tests loft iodine into the atmosphere, and it eventually falls out with rain. What doesn't make sense to me is why there is a bi... |
Without involving Euler-Lagrangian equations. I wanted to prove the Lagrangian equation of the first kind. Basically, D'Alembert's principle says
$$\sum_{i=1}^n (F^{a_i} - ma_{x_i})\cdot dx = 0,$$
where $F^{a_i}$ = Force applied in $x_i$ direction.
and $\phi(x1,x2,....,xn)=0$ is the contraint equation.
Hence, the Lagr... |
Consider two charge particles say $Q_1$ and $Q_2$ both are positive so they creates a electric field around it and both influence each other.
Is it possible that both particles (or charge) creates a Gravitational Field around it, in which intensity varies with distance, if it does then consider another example
Suppose ... |
Typically a traveling photon is described as being in a superposition of frequency modes $\hat{E} = \int g(\omega) a^\dagger_\omega d\omega + h.c. $ where often the $g(\omega)$ is some kind of pulse. Can $g(\omega)$ really be a pulse of any bandwidth? Putting it another way: Is the spectral profile of the pulse connec... |
So , everywhere I have looked for pair production it is stated that it cannnot happen in vacuum . Most proofs I have seen for that , state that the conservation of energy and momentum cannot be true at the same time without a body with which the photon will interact in the first place . In most of these proofs the mome... |
I could not understand why we can't use Gauss's Law to find the Electric Field of a finite charged sheet?
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I got a Doubt that what if the spring has mass
I found the following question
When one end of a spring (of mass m and length l ) is pulled with velocity V1 and other and with velocity V2 then velocity of a point on spring at a distance x from first end is given by formula
V1+ (x/l)×V2
I tried to prove this but I didn't... |
If a linearly polarized classical monochromatic electromagnetic radiation undergoes a scattering, does the scattered electric field have the same polarization as the incident electric field? I am looking for an answer (or deduce the conclusion mathematically) from classical electromagnetic theory of scattering.
|
In Hobsons's General Relativity: An Introduction for Physicists, pg. 64,
he gave two different expressions for the affine connection $\Gamma'^a_{bc}$ in a transformed coordinate basis $x'^a$ (the original coodinate basis is $x^a$).
The two expressions are
$$\Gamma'^a_{bc}=\frac{\partial x'^a}{\partial x^d}\frac{\partia... |
I was doing a Physics question and the question was: How does a satellite reduce their orbital radius. The answer was by ejecting mass (thus decreasing the mass) but it didn't explain more.
This is my explanation:
The gravitational force on the satellite must be constant, and so as F = GMm/r^2, when you decrease the m... |
If i have a null geodetic on a $g_{\mu \nu}$ metric, it's also null in a generic $\hat{g}=\exp{2\omega(x)}g_{\mu \nu}$ for any $\exp{2\omega(x)}\geq 0$?
What's the relation between affine parameter?
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How can you explain the statement that "the only central forces that result in closed orbits for all bound particles are the inverse square law and Hooke's law."
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Why is a compass not significantly affected by nearby (less than a couple meters) powerful magnets (such as those located inside home appliances and electronics) given Earth's magnetic field is just about 0.65 Gauss?
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I am following the book Braginsky and Khalili. Consider a measurement scheme where we connect a object to be measured to another quantum system which is then measured by classical devices.(Example: measurements of qubit states by coupling them to a resonator which is then coupled to transmission lines and amplifiers)
T... |
Can someone figure it out for me how this formula arrives
Provide derivation
courtesy HC VERMA vol 1
|
My teacher says that Energy is in the form of Electric field. I've also seen the mathematical prove. (The amount of work done in bringing a charge from infinity to that point in the Electric Field) But I don't really understand how it contains energy. Could someone explain it to me please?
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My notes state that the spectral decomposition formula is of the form:
$$ \hat{A} = \hat{A}\hat{1} = \sum{\hat{A} } |A_i\rangle\langle A_i | = \sum{A_i } |A_i\rangle\langle A_i | $$
Now consider the Hamiltonian as
$$ \hat{H} = \begin{bmatrix}E&K\\K*&E\end{bmatrix}$$
It would be easy to show that the eigenvalues are $$... |
Let's assume that we have two coordinates $q_1$ and $q_2$, a Lagrangian function $\mathcal{L}(q,\dot{q},t):=\mathcal{L}(q_1, q_2, \dot{q_1}, \dot{q_2},t)$ and a constraint $f(q,t) = 0$. Then I understand the procedure to obtain the equations of motions as constructing a new Lagrangian function $\mathcal{L}'(q,\dot{q},t... |
Pseudo force always acts in a non-inertial frame and it is always opposite to the direction of the body's acceleration. The backward push is of course inertia, but can we consider it in this manner (pseudo force) also?
If it is a pseudo force, then why is it visible? Pseudo forces are imaginary/fake forces that we can'... |
Let's consider particle in some potential $V(x)$. Newton law:
$$m \ddot x= -\partial _x V(x)$$
After Galilean transformation:
$$
x^\prime = x -vt
\;\;\;\;\;\;\;\;\;\;
t^\prime = t
$$
Form of equation must be the same:
$$m \ddot x^\prime= -\partial_{x^\prime} V(x^\prime)$$
From this we obtain:
$$m \ddot x= -\frac{\part... |
I was trying to understand the origin of flat bands for twisted bilayer graphene and had a basic misunderstanding.
The starting Hamiltonian is $$H = \begin{bmatrix} -iv_0 \sigma_{\theta/2}\nabla && T(r) \\ T^{\dagger}(r) && -iv_0\sigma_{-\theta/2}\nabla \end{bmatrix} $$
where $\sigma_{\theta/2} = e^{-\frac{i\theta}{4}\... |
I have learned that a component of a uniform circular motion is an example of SHM. And I have no question about it, I totally understand that. I also understand how we can derive formulas like $\vec{a} = - \omega^2 x$ and more. But my question is how can we use this formulas we derived for this one example of SHM to a... |
I had the following question in my Quantum Mechanics test.
A particle of mass m is subjected to a potential V(x) = β|x|, where β is a positive constant. Using the uncertainty relations (principle) estimate the ground state (lowest) energy the particle can have.
I had no clue how to approach this question because I didn... |
I have been reading the Classical Field theory part from The Quantum field theory book of Lewis H Ryder.
After defining classical field $\phi(x^\mu)$ he says something about adding variations on both the field, and the coordinates. $$\phi(x^{\mu}) \longrightarrow \phi(x^{\prime\mu})=\phi(x^{\mu})+\delta\phi(x^{\mu})$$
... |
In this video, you can use the equation to solve for the distance between the ball being dropped and when it hits the ground. All you need to know is the time it takes and the gravitational acceleration. In this case, it took 5 seconds. Thus, the distance, or the height of the building, is 122.5 meters.
In real life, ... |
I've seen many derivations in which Integration is used. But I don't understand the fact that why after going to a distance like $y$ or $x$, we take an element $dy$ or $dx$? Instead can't we take any other element of a different width say $d\theta$ after going to $y$?
What does this mean?
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The manometer contains a liquid of density $ \rho_m$.
The speed $ v_1 $ of the liquid flowing through tube at a broad neck area to be measured from the equation of continuity (10.10). the speed of consitrion becomes $ v_2 = \frac{A_1}{a} v_1$ . Then using bernoullis equation (10.12) for $h_1 = h_2$, we get:
$$ P_1 +... |
In Lewis Ryder's Quantum field theory's Classical field theory part, a certain variation of field is mentioned $$ \phi(x^\mu)\longrightarrow\phi(x^{\prime\mu})= \phi(x^\mu)+\delta\phi(x^\mu)$$
$$x^\mu\longrightarrow x^{\prime \mu}=x^\mu +\delta x^\mu $$
And then,
$$\frac{\partial x^{\prime \mu}}{\partial{x^\nu}}=\delta... |
The objective is to prove that the Lagrangian:
$$L'=\frac{2\dot x+\lambda x}{2\Omega x}\tan^{-1}(\frac{2\dot x+\lambda x}{2\Omega x})-\frac{1}{2}\ln(\dot x^2+\lambda \dot{x } x + \omega^2x^2), \qquad \Omega=\sqrt{\omega^2-\lambda^2/4},$$
is equivalent to the lagrangian of the damped harmonic oscillator:
$$L=e^{\lambda ... |
Here we have an example QHO wavefunction squared in blue overlayed an equivalent CHO probability distribution. I'm trying to understand intuitively why the QHO result has zeros, i.e. points where we would not detect a particle.
Can one imagine the quantum result as somehow a 'bound particle wave interfering with itsel... |
I am confused as to which parameter I should start off with in order to optimizing the best performing solar cell. There are parameters like Thickness, Bandgap, Electron Affinity, relative Dielectric Permittivity, Effective conduction and valence band density, Electron and hole thermal velocity,
Electron and hole mobi... |
If a current carrying loop is in external magnetic field it feels the force and moves to its equillibrium position. Similarly, in quantum level will electrons revolve nucleus in a lined up manner for externalmagnetic field ?(Thinking revolving as not an orbit but its its direction of revolving makes it line up) Can we ... |
When reading about Astra satellites on Wikipedia (https://en.wikipedia.org/wiki/Astra_1KR), I saw that the period of the Astra 1KR satellite, positioned at 19.2° E, is 1,436.1 minutes (source: NORAD data).
That is 3.9 minutes short of a day (1440 minutes), how is that possible with the satellite still being geostationa... |
In University Physics with Modern Physics by Hugh Freedman in Chapter 41.3 they go about solving the Schrodinger equation for the hydrogen atom.
At one step they say to substitute the following function:
which is a function of spherical coordinates into the Schrodinger equation below:
Once you do this you are suppose... |
Ignore the friction in the problem.The string used is mass less.
Ok, we usually see these kinda of situation in the pendulum toys in our cars.When we accelerate or cars in the forward direction we usually find the toys(ones hanging via string) accelerate in the backward direction,and more
interestingly if we keep our ... |
I want to generalize the Wigner overlap formula,
$Tr( F G ) = 2 \pi \int_{-\infty}^{\infty} dq \int_{-\infty}^{\infty} dq W_F(q,p) W_G(q,p)$,
where $W_F(q,p)$ and $W_G(q,p)$ are the Wigner functions of the operators $F$ and $G$, respectively.
This formula is stated in literature for two operators $F,G$ (see e.g. Measur... |
I was watching some lectures on qubits. They were talking about how to generate a Bell state. They described it as follows:
Prepare state 00:
$$\left |0 \right> \otimes \left |0 \right>$$
Apply the Hadamard:
$$ (H \otimes I)(\left |0 \right> \otimes \left |0 \right> ) = \left |+0 \right> = \frac{\left|00 \right> + \l... |
In a review on quintessence, the equations of motion (EoM) for the action
$$
S=\int\!\mathrm{d}^4x\sqrt{-g}\left(\frac{M_p^2R}{2}-\frac{g^{\mu\nu}\partial_\mu\phi\partial_\nu\phi }{2}-V\left(\phi\right)\right)+S_m,
$$
are given by
$$
3M_P^2H^2=\dot{\phi}^2/2+V(\phi)+\rho_m
$$
and
$$
2M_p^2\dot{H}=-[\dot{\phi}^2+(1+\ome... |
An ellipse has a uniform linear positive charge density in upper half (total upper half part charge $+Q$ ) and a uniform linear negative charge density in lower half (total lower half part charge $-Q$ ) as shown in figure. Here, semi-minor axis $b<a$ semi-major axis. Select the correct statement about the magnitude of ... |
Crystals are composed of the same stuff assembled in a periodic fashion.
I understand that there are possible and less possible bonds. Like complementary electric charge, ie. things must stick together or at least not repulse each other.
However I find it difficult to understand why this development process (crystal gr... |
When ever the force and velocity are in thesame direction(0°), an object speeds up. When ever the force and velocity are in opposite directions(180°), the object slows down. Also , when ever force and velocity are at 90° to each other, the object is known to describe a circular path with constant velocity. Now what h... |
In literatures of thin film growth I often see the unit QL. It often occurs at contexts like "a 64 QL film," "the growth occurs QL-by-QL," and "the growth rate was found to be 1 QL/min." I suspect L means layer, but I am not sure what Q means.
|
I have a long straw ("small" diameter tube of constant cross-section) hanging vertically above me. The straw is filled with liquid (water). I blow a finite volume of air (gas) into the lower end of the straw. The input of gas into the lower end of the straw is such a way that the gas spans the entire diameter of the st... |
If there is an inductor in a certain electrical circuit, from Faraday's Law we know that $$ \oint \vec{E} \cdot \vec{dl} = -\frac{d\phi_{magnetic}}{dt}$$
I see everywhere that when doing this line integral over a circuit with an inductor, the change in magnetic flux is $-L\dot{I}$, but shouldn't the magnetic flux be me... |
The time independent wave function for a bound state given some potential function $V(r)$ is given by the time independent Schrödinger Equation
$$E\Psi=-\frac{\hbar^2}{2m}\left(\frac{\partial^2\Psi}{\partial{x^2}}+\frac{\partial^2\Psi}{\partial{y^2}}+\frac{\partial^2\Psi}{\partial{z^2}}\right)+V\Psi$$
One example of a ... |
From the measurement postulate, we are told that every observable quantity is represented by a Hermitian operator $\textbf{A}$, where the eigenvalues of said operator gives the possible measurement outcomes. In many body physics it often the goal to find the ground state of the system. For exmaple a magnetic lattice of... |
I was reading about how materials get charged by friction. In this resource it is stated that
The triboelectric charging process (a.k.a., charging by friction) results in a transfer of electrons between the two objects that are rubbed together. Rubber has a much greater attraction for electrons than animal fur. As a r... |
Let $(x, t)$ and $(x', t')$ be the coordinate system used by the observers $O$ and $O'$. Let O' move with velocity v=Bc along their common positive x axis. If X+=x+ct and X-=x-ct are the linear combinations of the coordinates,
Write down expressions of X+' as function of f(X+, B) and X-' as function of f(X-, B).
Her... |
According to https://www.britannica.com/science/Schwarzschild-radius, the Schwarzschild radius for a black hole with the mass of the Sun is about 2 miles. My question is what is inside of it? Is whatever is inside of it similar to what surrounds it? Can particles escape? Or does the whole sun have to collapse into it f... |
Prof Wetterich has proposed that atoms are shrinking rather than the Universe is expanding.
Here is a 2013 Nature News article describing his theory:
https://www.nature.com/news/cosmologist-claims-universe-may-not-be-expanding-1.13379
Here is his 2013 paper "A Universe without expansion":
https://arxiv.org/abs/1303.687... |
So, as far as I understand, sounds are ripples through a material. If you strike a rock, then (ignoring thermal motion, if we may) the molecules in the rock start off stationary, then wiggle back and forth as the waves pass through them, then return to a stop. How far do they move? I assume it varies based on materi... |
On the web and in my books, there are two possible reasons given for why the charge on a conductor resides entirely on the surface.
The electric field inside a conductor is 0.
The like charges repel each other until they are at the maximum possible distances from each other.
Regarding the first explanation, I know th... |
In special relativity the energy of a material point is defined
$$E= \frac{m_0}{\sqrt{1-v^2/c^2}}c^2,$$
and the momentum is defined by
$$\mathbb{p}= \frac{m_0}{\sqrt{1-v^2/c^2}}\mathbb{v},$$
where $\mathbb{v}$ is the velocity of the particle.
I am wondering whether the conservation laws of energy and momentum in spec... |
I'm trying to evaluate
$(\hat{a}+\hat{a}^\dagger)^k|n\rangle$
Where $\hat{a}$ and $\hat{a}^\dagger$ are ladder operators and $|n\rangle$ the $n$th Fock state.
For this, I separated the problem in three parts: $k<n$, $k=n$ and $k>n$.
In this part I'm a bit confused: Is it possible to evaluate such operations? Some tips ... |
Suppose we're given the following Hamiltonian: $$\hat{H}=\frac{\omega}{\hbar} \left(\hat{S}_+^2+\hat{S}_-^2\right)$$ Suppose also that we measure $\vec{S}^2$ and get $6\hbar^2$, i.e. reduced to the $s=2$ subspace, and want to find all the possible energies (aka the eigenvalues of the Hamiltonian operator in the relevan... |
Is it true that Earth didn't get its water by cometes impacts as there are no subocean craters so it seems water acted as a comete bumper long before in the past?
|
According to my research, I've seen Newton's Cradle that can last only 20-30 seconds max. Or the one that I bought very cheaply, only 5 seconds. I suspect the friction from the strings plays an important part in shortening its momentum. I could be wrong.
I wonder what are the factors that can make it last a long longer... |
I was reading this answer:
https://physics.stackexchange.com/a/346489/230132
It seems its author ceased to visit SE since April so they will probably never answer my comment. So I am asking a question here.
The answerer says that the reflection between two mirrors parallel to each other will keep getting smaller and sm... |
When we are to determine the emf of a cell, we find the null point and balance length using the cell whose emf is to be found out.
But there is some internal resistance of the cell.
Why isn't any potential of the cell (whose emf is to be found) dropped at its internal resistance?
I may reframe my question as: why is th... |
I'm taught in class that for a symmetry $\phi \rightarrow \phi + \delta\phi$ (and leaving the spacetime coordinates alone), the Noether current is
$$ J^\mu = \frac{\partial L}{\partial (\partial_\mu\phi_n)} \delta\phi $$
but the expression $\delta\phi$ is very unclear to me exactly what it means. Sometimes, $J^\mu$ is ... |
I can't seem to find a white laser pointer for sale anywhere. Is it just me or is it somehow not possible to make it? I see only color laser pointers like red, green, blue, etc.
|
For the Value Axis (Normalized Solar Intensity) what does the value represent? Is it the Solar Irradiance rate normalized in a specific equation or is it something else?
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I'm installing overhead water supply system, which is to be installed on the ceiling. I want to have 1000 litre capacity. The water heater that I use, requires some pressure at the inlet pipe. So will two smaller tanks(500 Litre each), connected at bottom provide more pressure than single 1000 litre tank?
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Consider the Penrose Diagram of Collapsing Gravitational matter :
Any radial light ray (say P) originating from $\mathscr{I}^{-}$ is bound to end up in the Black Hole. The causal past of $i^{+}$ implies that anything in that region can (and not must) influence it. But even though P lies in the... |
i was reading about magnetic circuits with air gaps and found that H in the gap (Hg) and H in the core of the magnetic material (Hc) were different, but the B field was equal throught (since flux will be same, and fringing effect is neglected and hence area of cross section will be same). This made little sense, that w... |
A sail ship leverages the keel’s resistance to turning moments to allow a wind crossing a sail at an angle to tack, achieving a speed greater than the driving wind. But is it possible at all for an airship to also translate turning moment energy into forward energy? Such that a keel surface and sail surfaces can resul... |
Please excuse my ignorance or poorly worded question (this is my first one), but I am wondering how to go about deriving the parametric equations for the x and y motion of an object traveling along a 2D path (like $y = x^3$) at a constant speed.
Here are the things I "think" I know:
$$s = \sqrt {\frac{dy}{dt}^2 + \frac... |
Would a flattened round balloon tend to orient vertically or horizontally, assuming neutral buoyancy? Does this shape provide a righting moment against pitch and roll?
By flattened, I do not mean “flat”. It is simply smaller in one axis than the others, by some arbitrary measure.
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If a neutron has no identifiable electric charge or polarization, as far as anybody has been able to determine, how can it have a value for 'electric polarizability'?
Wikipedia has a value listed that is only smaller than that for the proton.... I'm confused....
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