# All Questions

1answer
70 views

### What is the place of an electromagnetic field in the electromagnetic spectrum? [closed]

What place should I give an electromagnetic field (produced by a current conducting coil) in the electromagnetic spectrum? What will its wavelength and frequency be?
1answer
122 views

### String-net models on non-trivalent lattices

I have just started reading about string net models. The following aspect wasn't entirely clear to me: String net models are most naturally defined on trivalent networks, that is to say networks ...
1answer
61 views

### Explanation request for flashes of light [closed]

I have observed what I believe to be the same phenomenon on two occasions and wanted to ask for possible explanations. Both times, I saw flashes of whitish light, near the ceiling of a room. They ...
1answer
85 views

### Work-Energy-Power Relations

A wind-powered generator converts wind energy into electrical energy. Assume that the generator converts a fixed fraction of the wind energy intercepted by its blades into electrical energy. ...
2answers
186 views

### What does library number 539 mean in physics books? [closed]

Every book I borrow have have this number in them. Even my library categorizes them with this number. Is it a universal particle physics book number?
1answer
90 views

### What is Photoproduction

I wonder what photoproduction means in the context of pion decay and vector meson dominance? What is the reaction formula, Feynman diagram for such a photoproduction thing? Is it simply a reaction ...
1answer
330 views

### Power counting with a cutoff

In Effective Field Theory video lectures found here, the professor explained power counting in effective field theories and the difficulties of power counting associated with loop diagrams. He then ...
1answer
82 views

### Is the plane wave model always valid in reflection and transmission?

my question is related to another one I asked, but I foolishly made that question about several things (experiment, computation, theory) at once so it was confused. I was talking to my boss about ...
3answers
2k views

### Prove EM Waves Are Transverse In Nature

Why we say that EM waves are transverse in nature? I have seen some proofs regarding my question but they all calculate flux through imaginary cube. Here is My REAL problem that I can't here imagine ...
0answers
35 views

### Would anyone suggest me usefull web resources on lie groups and lie algebra and a good book to start with? [duplicate]

Would anyone suggest me useful web resources on lie groups and lie algebra and a good book to start with?
1answer
2k views

### What is the difference between dispersion and diffusion?

What is the difference between dispersion and diffusion? Currently I believe, that diffusion is the mixture of molecules due to Brownian motion. So I read everywhere, that it happens with magnitude of ...
2answers
293 views

### Reason why $F^{\mu\nu}F_{\mu\nu}$ and $\tilde{F}_{\mu\nu}F^{\mu\nu}$ are Lorentz invariant

I'm trying to think of an intuitive reasoning for why $F^{\mu\nu}F_{\mu\nu}$ and $\tilde{F}_{\mu\nu}F^{\mu\nu}$ are Lorentz invariant. By this I mean that I don't simply want to show that they remain ...
3answers
124 views

### Entanglement in single particle state

Is it possible that we have entanglement in different degrees of freedom of a singe particle. like spin and linear momentum .
0answers
43 views

### Space time curvature due to electric charge or magnetic charges [duplicate]

since we know that gravitational force is nothing but a curvature in space-time. I have a similar analogous for the electric or magnetic charges. Similarity is that both electromagnetic and ...
0answers
23 views

### It's commonly said that the existence of antiparticles “saves causality”. How? [duplicate]

The way I've always thought about is something like this: If measurements of space and time are essentially indeterminate (indeterminacy principle), then an entity "traveling at less than the speed of ...
1answer
227 views

### Understanding collision terms in Boltzmann equation

I am reading a paper that deals with the Boltzmann equation. They add a collision which is supposed to account for collisions which happen when particles are within a radius of $d$ from each other. ...
1answer
733 views

### Calculating the energy of an electron given the wavelength

Okay, so I know that the wavelength of an electron is 5e-7m and I am asked to calculate its minimum velocity and hence minimum energy. Calculating the minimum ...
1answer
138 views

### Phase Plot for Harmonic Oscillator

This is probably gonna be a dumb question but I don't know exactly where I am making the mistake. I have been taught in highschool that simple harmonic oscillator phase plot is the $sin(\omega t)$: ...
0answers
46 views

### The orthonormality conditions for plane waves

The notes I'm using for QFT give an orthonormality condition for the following plane wave: \begin{align*} u_{r,k}(x) = \frac{1}{\sqrt{V}} \varepsilon_r(\mathbf{k})e^{ik \cdot x} \end{align*} (where ...
0answers
176 views

### Physical significance of Taylor and Maclaurin series - What is the significance of defining a Maclaurin series in Mathematical Physics?

In physics, usually Taylor series is used to express a quantity which keep changes with coordinate. For example the potential energy of a molecule changes with coordinate, so we express the potential ...
0answers
50 views

0answers
31 views

### Breatheability of atmosphere above 3000 meters [closed]

I would like to offer you a slight correction on your statement that 3000 m is about the limit of breathable atmosphere. Unless I misunderstood you, I need to point out that many people live in ...
3answers
121 views

### Superconducting wire in a Magnetic Field?

A superconducting wire($SC$) is moved rapidly in a magnetic field( $1$ $Tesla$), what would happen to the wire? Are there any forces induced of attraction or repulsion? In a typical conductor, we ...
1answer
72 views

### Info request on studying QIT/QIS or QM with a Computer Science background [closed]

I've been considering a career change for a long time and recently discovered the Two-Slit Experiment, which, to put it frankly, blew my mind. I then started some hefty reading and investigation into ...
4answers
701 views

### Is a capacitor in an open circuit charged?

Say I have a circuit consisting of a battery, a wire, an open switch, and a capacitor. The circuit is open since the switch is open. My book says that the capacitor will only be charged when the ...
3answers
207 views

### Integration constants in Maxwell's equations (ambiguousness?)

In classical electrodynamics, if the electric field (or magnetic field, either of the two) is fully known (for simplicity: in a vacuum with $\rho = 0, \vec{j} = 0$), is it possible to unambiguously ...
2answers
262 views

### Does the stretching of space time have a limit?

Why does the stretching of spacetime have no limit? If multiple universes exist. Wouldn't each universe occupy a defined area? If these universes do occupy a defined area wouldn't there be a limit to ...
1answer
102 views

### Can resistance of wire be ignored

I was doing some physics homework involving direct current circuits and resistors in series, and I started to question the accuracy of the following property of resistors in series, namely that the ...
1answer
513 views

### Why the electric potential of earth is zero?

For a localized charge distribution the potential is set to zero far away from the charge distribution (at infinity) Now, when grounding a conductor, i.e. connecting it to Earth, it is said that we ...
2answers
59 views

### energy of electrons outside an atom

The higher the quantum number(energy levels)m the higher the energy. What does the energy refers to? Kinetic energy, potential energy, or the total mechanic energy?
1answer
101 views

### Pathria's “Statistical Mechanics” first edition [closed]

Does anyone know where I could find and purchase the book "Statistical Mechanics" by R. Pathria, in 1st edition (the 2nd and the 3rd are readily available, but I really need the first). I believe the ...
1answer
316 views

### Changing the resistance of a circuit

I am wondering, when we change the resistance in a circuit, does the voltage tend to increase or the ampere decrease? More specifically, under what conditions does what happen? E.g. If we have a ...
1answer
232 views

### Why would a pendulum experiment give $g > 9.8\ \mathrm{m/s^2}$?

I am taking an introductory lab course in which we've done an experiment on the physical pendulum. We've seen that for small oscillations, the period is ...
0answers
189 views

2answers
142 views

### Speed of Sound/Push in Supersonic Flight

I've learned from things like the Veritasium Slink Drop and the old "break the speed of light by pushing on the end of a very long pole" thought experiment that objects have a "speed of push" which is ...

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