# All Questions

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### Can a wave possess spin?

Since a matter wave is associated with a particle in quantum mechanics, does the wave spins ? I mean, can we visualize the spinning of wave or is it possible that the wave spins ?
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### 'hypersurface orthogonal' component of covariant derivative of normal vector

I believe that answer to my question is rather trivial but I can't seem to get my head around it. In context of ADM formulation of gravity (or any other differential geometry context, I guess) the ...
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### Supercooling Liquid in an Adiabtic Container

I have a liquid that has been supercooled to -10 degrees celsius, which is then isolated into a adiabatic container. Q : Will there be any spontaneous change? (I'm thinking yes since the ...
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### Calculate analytically the time until two spheres meet due to gravitation

Imagine you have two homogeneous spheres with the same diameter of $d=0.1 m$. They have the same mass $m = 1 kg$. The distance between the centers of mass is $r= 1 m$. Their electrical charge shall be ...
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### Stern Gerlach Experiment

Since l=0 for a valence electron in 5s state of silver, L=0 and therefore magnetic dipole moment is also 0 which means that the beam should not have deflected at all. So, we introduced the property of ...
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### Truss Analysis with multiple moments creates linear combinations

So in my engineering statics course we have been doing a great deal of work with trusses and machines, and a part of the physics behind it has really been confusing me. Just as a note, I also have ...
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### Numerical Tools to find Braiding Statistics of Quasiparticles

While certain classes of systems that exhibit topological order can be solved exactly (such as the Toric Code, Abelian FQH Edges, etc.) there also exist systems (think of perturbed versions of the ...
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### Characteristic polynomial of a Matrix

In fact, this problem is more likely to be a math problem. When I read a paper(http://arxiv.org/abs/0707.2875), the author includes the characteristic polynomial for a type of matrix $A_k$ with ...
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I'm reading Rubakov's "Classical Theory of Gauge Fields", and I'm having a little bit of trouble with problem 7, p 15: Using an expression of the type $E = \int d^{3} x \frac{\delta L}{\delta ... 2answers 37 views ### An electron in$s$state If an electron is in$s$state, for example in 1s state for Hydrogen or 5s state for Silver atom,$\ell=0$. So,its total angular momentum$L$is also equal to 0. So, what is electron actually doing in ... 0answers 32 views ### What precisely does the 2nd law of thermo state, considering that entropy depends on how we define macrostate? Boltzmann's definition of entropy is$\sigma = \log \Omega$, where$\Omegais the number of microstates consistent with a given macrostate. If I understand correctly, this means that it only makes ... 0answers 22 views ### What is angular speed after 2nd collision? speed of block? time? [on hold] Question with graph: For a) I got that the mass for rod must equal to block for the block to stop immediately after the collision (perfect velocity transfer) so the initial speed for rod after ... 2answers 32 views ### Is the moment of a force the same about any point? I know that when a body is is equilibrium There is zero resultant force in any direction, i.e. the sum of all the components of all the forces in any direction is zero The sum of the moments about ... 0answers 26 views ### Three level degenerate Hamiltonian with perturbation I have the following system $$H=\begin{pmatrix}0&0&0\\0&0&0\\0&0&E\end{pmatrix}$$ $$V=\begin{pmatrix}0&0&\alpha^*\\0&0&\alpha^*\\\alpha&\alpha&0 ... 0answers 4 views ### Electrons Orbiting Sphere Magnet in Crooke's Tube Were I to assemble a Crooke's Tube and insert a spherical magnet, with the poles of the magnet perpendicular to the electron stream, would the electrons begin to orbit the poles of the magnet as in ... 0answers 18 views ### Time Dependent perturbation driven at resonance SO I am looking at driven perturbations, and I came across Fermi's golden rule here. It has a term that goes as:$$P\propto\frac{1}{\omega_{fl}-\omega}Now I am curious how to go about solving this ... 1answer 21 views ### Height and pressure in atmosphere [on hold] Assuming an atmosphere will obey the hydrostatic equation dP/dz = -pg and the ideal gas law P = (p/uM)kT where M is the mass of a hydrogen atom, u is the mean molecular weight of the atmosphere, p is ... 0answers 19 views ### Has this boundary condition been used in fluid flow? I would like to know whether anyone has seen a boundary condition used in a fluid flow problem, of the following type. Suppose viscous incompressible fluid is to the left of a plane x_1=a, so the ... 0answers 22 views ### Electromagnetic induction problems [on hold] 1 What will happen to the illumination of the lamp (increase/decrease/remains constant) when decreasing the resistance R. 2 In the given figure a long wire is carrying a current of 5A, what is the ... 0answers 15 views ### Electric current problems [on hold] 1 Calculate the equivalent resistance Ans: 8/3 Ω 2 Calculate the equivalent resistance Ans: 5Ω I've posted the answers for these problems to prove that this isn't some sort of homework,all i ... 0answers 15 views ### Powered Aquarium Siphon [on hold] I have an idea for a simple aquarium fill/drain construct made of PVC. Here is a basic diagram of my idea. When it is filling the fill valve, which is attached to a kitchen sink, is open and the ... 0answers 14 views ### Classical Scattering of Slow Neutrons by a Diatomic Molecule [on hold] Consider an experiment in which slow neutrons of momentum \hbar k are scattered by a diatomic molecule; suppose that the molecule is aligned along the y axis with one atom at y=-b and the ... 1answer 24 views ### Calculating kWh from time series of kW I have a time series of kW where each sample is measured at regular intervals (10 seconds). Could anyone explain to me how could I calculate the total power consumed (kWh) over an hour? Thanks 1answer 14 views ### Why the crest of water absorb more light than the trough of water? I have done my experiment using water ripple to study the behavior of waves. I know that the crest will absorb more light than the trough so that the image created on the white paper sheet appeared to ... 0answers 19 views ### Relationship between the fall time and projected area I am investigating the relationship between the fall time of a paper tray and its projected area. In this investigation I have been using the following variables: Controlled Variable: The air ... 0answers 26 views ### Quantization of linear momentum in 'particle in a box' problem [on hold] I am new in Quantum Mechanics. I am 2nd year UG (Physics Major). I had few conceptions to clear.. I was going through particle in a box problem ...So while deriving that we used the time independent ... 2answers 67 views ### Why do clouds fly? I know it's probably the most stupid question there is, but why do they fly are the clouds lighter than air? What's keeping those tiny ice structures floating miles about the ground? I've been looking ... 1answer 31 views ### What is meant by incompressible flow? What is meant by incompressible flow? The density of the fluid is a constant, \rho = constant The density of a fluid has a spatial dependence but remains constant in time, \rho = ... 2answers 35 views ### Probability distribution in phase space and Liouville's theorem? We can define a probability distribution over phase space (say 1D) \rho(x,p) such that, for example,\langle x\rangle = \int x \rho(x,p) dxdp$$etc. It can be shown here that such a distribution ... 0answers 27 views ### Who was the R. Dolen behind Dolen-Horn-Schmid duality? [on hold] Can you provide biographical information for R. Dolen, known for Dolen-Horn-Schmid duality? 1answer 73 views ### Why isn't the \lvert\phi(x)=0\rangle Fock eigenstate the vacuum state? If, in a QFT of a scalar field \phi, a Fock space n-particle position eigenstate \lvert x_1\cdots x_n\rangle is given by$$ \lvert x_1\cdots x_n\rangle ... 0answers 20 views ### Show the Lie algebra is the same forSU(2) \times SU(2)$and Lorentz group So I know: $$[\sigma_{I},\sigma{j}] = 2i \epsilon_{ijk} \sigma_{k}$$ So two products of this should give us the Lorentz group:$SO(4) = SU(2) \times SU(2)$Where$SO(4)$has 3 Lie algebra which can ... 0answers 9 views ### What is clock or phase adjustment in projectors? Why its proper setting eliminates strange behaviour of 1px lines/ I'm doing experiments that require using a big, thin, contrast grid, for example 1 black pixel and then 1 white pixel alternately. I've met with a few DLP projectors and in each of them I had to ... 1answer 25 views ### what will happen when you attached your hand to a two 220 volt wire of their phase defference by 120 degree? [on hold] What will happen when you attached your hand to a two 220volt wire with their phase difference by 120 degree? 0answers 87 views ### Is this picture of the universe valid? Universe as a whole has zero entropy. Since entropy does not grow, the universe has no time arrow. It does not change over time, at best it only fluctuates. Since following Holographic principle the ... 1answer 23 views ### First Order Time Depenent Perturbation theory of particle in magnetic field So I am dealing with the following hamiltonian, and the following perturbation: $$H=-\mu B_0\sigma_z$$ $$V=\mu B_1(\cos(\omega t)\hat x-\sin(\omega t)\hat y)\cdot{\bf \sigma}$$ I am asked for the ... 0answers 28 views ### What is the Electric field of an infinite line charge while on the same axis [on hold] Consider a line of charge (w/ charge per unit length lambda(L)) which extends along the x-axis from$x = -\infty$to$x = 0$. (a) Find the electric field at any point along the positive x-axis (b) ... 1answer 40 views ### Spin connection in higher dimension I have a problem regarding computation of spin connection in the case where One or more dimension is compactified. For example if we take a$D+1$dimensional bosonic string action and write the$D+1$... 0answers 11 views ### Solving relativistic particle decay problem in Landau In Landau, Lifshitz "The Classical Theory Of Fields" in$\S11$"Decay of particles" a problem is given: A particle moving with velocity$V$dissociates "in flight" into two particles. Determine ... 1answer 25 views ### What happens to an Electron when its charge is transferred elsewhere I am vastly uneducated in the areas of physics and chemistry. I am aware that electrons do have a mass, and that they carry a charge. I think that when an electron gains energy it becomes excited and ... 3answers 55 views ### Why don't the kinematic equations agree with calculating velocity one second at a time? A car is moving at a velocity of$10 \, \text{m}/\text{s}$. After point$A$no acceleration is provided. By simple measurement, the acceleration is found to be$-1 \, \text{m}/\text{s}^2$. Using ... 1answer 49 views ### Sum of forces with liquid in rotation It's not homework (I'm teacher). I would like to compute sum of forces on this study : The shape is symmetrical like that I'm sure the center of gravity is in the center of the shape. I compute ... 1answer 32 views ### Distance travelled given velocity at various moments of time [on hold] I am trying to solve a problem where I need to find the distance travelled at the end of the nth second and my input data contains only velocities at different time instances. Say for instance I ... 1answer 66 views ### A graphical proof that the$SU(2)/\mathbb{Z}_2$vortex is non-orientable The text, see [1], compares the vortex solutions of a spontaneously broken symmetry$U(1) \rightarrow 1$and$SU(2)\rightarrow U(1) \rightarrow \mathbb{Z}_2$. The vortices can be classified by ... 1answer 22 views ### Why are there interference patterns inside a diffraction envelope? When double-slit diffraction occurs, there are interference patterns inside, say, the central diffraction maxima (or envelope). I am trying to understand how these interference fringes are created. ... 1answer 14 views ### Why maximum energy transfer at natural frequency even if max amplitude occurs below$f_0\$

This is a paragraph from my book: "For a damped system, the resonant frequency at which the amplitude is a maximum is lower than the natural frequency.However, maximum transfer of energy, or energy ...
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### Two-Body with external force - energy confusion

Setup Imagine a two-body system of masses under a classical mechanics model. The separation and mass-ratio doesn't matter for this example. Presume they are initially stationary. Now suppose that we ...
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### How do RGB colors work? [duplicate]

They say that all colors can be formed by mixing Red, Green, and Blue appropriately. Is it true? Isn't the Fourier basis infinite dimensional? Or does it turn out to be the case that only three ...