2
votes
2answers
37 views

Spring behaviour under high atmospheric pressure

We have a spring inside a chamber. We compress the spring and then let it decompress freely. Will its decompression (its speed and displacement) be the same if the air pressure of the chamber is $1\;\...
2
votes
1answer
115 views

What does “downshear” mean?

I occasionally read descriptions such as "downshear of the vortex" in meteorological publications. What does this mean?
3
votes
1answer
72 views

What is the physical meaning of the parameter of a Poisson distribution?

I have done a laboratory session at my university where I had to check that the disintegration of nucleii follows a Poisson distribution $$P(n)=\frac{\lambda^n}{n!} e^{-\lambda},$$ where $P(n)$ is ...
0
votes
1answer
33 views

Molecular Orbitals and Nodal Symmetry

I am currently doing a solid state physics class and am stuck on a concept regarding molecular orbital (MO) hybridization. As an example consider an HF molecule bonded along the z-axis. This molecule ...
0
votes
1answer
127 views

How is a variable potential divider able to reduce current/voltage through a component to zero, unlike a variable resistor?

For example, the diagram in my text book shows a filament lamp, in series with a uniform resistive wire, which can have its voltage and current varied by moving the sliding contact, e.g., a ...
3
votes
2answers
686 views

Is the reciprocal of Entropy easier to understand? [on hold]

"A thermodynamic quantity representing the unavailability of a system's thermal energy for conversion into mechanical work, often interpreted as the degree of disorder or randomness in the system." ...
8
votes
4answers
273 views

A contradiction between Biot-Savart and Ampere-Maxwell Laws?

I came across a problem that I cannot get my head around. Consider two very small spherical metallic balls given charges +Q and -Q. Assume that they can be approximated as point charges. Now, they ...
-2
votes
1answer
29 views

Wave nature of light [on hold]

I'm currently working on a project to demonstrate the wave nature of light. Now, my question in specific is: How could the phenomenon of interference be used to MATHEMATICALLY explain the wave nature ...
0
votes
1answer
16 views

What is conductive half space in the context of electromagnetics?

What is conductive half space in the context of electromagnetism? I was looking into skin effect, where the author has used half space of a cylindrical conductor. But I am lost on what it means.
3
votes
1answer
821 views

Phonon Momentum

I am reading Charles Kittel's solid state physics and wondering what's the mechanism that neutron waves and photons can interact with phonons and the process obey the generalized momentum-energy ...
0
votes
0answers
19 views

Electric field inside hollow metallic sphere which is not closed

Suppose I have a charged hollow metallic sphere. It is sure that the electric field inside the sphere is zero, in static case. ( I got explanation for this from the previous discussions in this site). ...
-2
votes
0answers
30 views

What is Coulumb force at zero separation in classical picture [on hold]

Assume a classical world. What would be force between 2 point charges if their separation tends to zero? Assume charges are static. My professor claimed it would be finite. I request you to ...
18
votes
4answers
3k views

Why don't loop currents produce light?

If a charge travels in a circle it must accelerate, thereby producing EM. However, a wire in a circular loop is analogous to many charges moving in a circle. So, why don't circular currents produce ...
2
votes
1answer
63 views

How does a photon 'know' when to reflect in case of refraction? [on hold]

In thin-film interference and in glass fibers refraction is involved. Depending on the angle of which a light ray enters the material it will be reflected or transmitted. The refraction depends on the ...
-1
votes
0answers
18 views

Velocities from rotating frame of reference to fixed frame of reference [on hold]

I have the following flexible structure, where P1 coordinate system is fixed to the ground and P3 is rotating around the $y_3$ axes. I would like to model this structure as a simple steady state ...
0
votes
0answers
15 views

reference request: 2D turbulence

I'm reading papers regarding the 2D Navier-Stokes equations. But I don't have a physics background. Would anybody come up with some introductory references of 2D turbulence which contain the following ...
0
votes
0answers
45 views

Inside computer processors what physical phenomena represents a 1 or 0 [on hold]

I understand how transistors work as switches but am struggling to understand what is detected as the output that is know to be a one or zero. I aim to understand the link between the current flowing ...
-1
votes
0answers
32 views

Question about electric flux [on hold]

Question: Suppose a point charge is located at the center of a spherical surface. The electric field at the surface and the total flux through the sphere are determined. If the radius of the sphere ...
0
votes
0answers
29 views

Bulbs glow with different brightness in one arrangement and the same brightness in the other arrangement

The question is: Mr.X decorated his house with fairy lights on a celebration.He bought 40 bulbs and operated at 220V. He found all the bulbs are glowing with different brightness. He called his friend ...
4
votes
1answer
538 views

Determining potential in coaxial cylinders

If I have two conducting, coaxial cylinders as shown: The potential at the outer cylinder is = 0. And I apply a potential difference across both cylinders in the form $V_a - V_b = V_{ab}$, how can ...
2
votes
2answers
60 views

Bulk-to-Boundary propagator

How can I show that the bulk-to-boundary propagator $$ K(z,x;x')~=~\frac{z^{\Delta}}{[z^2+(x-x')^2]^{\Delta}} \tag{1} $$ goes as a delta function near the boundary $$ K(z,x;x')~\sim ~z^{d-\Delta}\...
-3
votes
0answers
25 views

Renormalization Group in Condensed Matter [on hold]

Are RG calculations done only in the vicinity of a phase transitions in cond-matt?
0
votes
0answers
23 views

Stuck with 2D kinetics problem [on hold]

I've been trying to solve this exercise for the last four hours and I'm totally stuck. The problems goes like this: Given the mechanism in the image, located in the vertical plane, the OB cord ...
0
votes
1answer
46 views

Interpretation of the vector current in field theory

In field theory we write $$J^\mu=\bar{\Psi}\gamma^\mu\Psi$$ But I can't understand why it is so. Could anyone explain each of the terms in the multiplication?
0
votes
0answers
11 views

How do rockets fly? [duplicate]

Is it that when a rocket loses its mass due to the escaping gases that results in its acceleration due to the same force acting upwards? If so, how is Newton's Third Law associated with it?
0
votes
1answer
40 views

How to understand CP-violation in kaon systems with Feynman diagrams and matrix elements?

I am trying to understand CP-Violation in the Kaon system using feynman diagrams and matrix element. Here is a slide from Mark Thomson corresponding exactly to what I am looking for (http://www.hep....
0
votes
1answer
47 views

Can revolving movement also generate gravitational waves? [on hold]

If an object revolves around a circular path at the speed of light could it still generate gravitational waves and what would be the simulation in inner area?
5
votes
1answer
236 views

Difference between Cartesian product and tensor product on gauge groups

After a comment of John Baez to a question I asked on MathOverflow, I would like to ask what the difference between, for example, $SU(3)\times SU(2) \times U(1) $ and $SU(3) \otimes SU(2) \otimes U(1)$...
2
votes
1answer
46 views

Gauge Theory of Superconductors

I'm trying to understand better the nature of the gauge redundancy and the Higgs mechanism in superconductors. Specifically, I'm looking for a good reference that explains monopoles, vortices, and ...
0
votes
0answers
17 views

What force is needed to slide a plate off a magnet?

I have read related the wiki article but I am not able to find a solution to my problem: how to find the min force needed to separate a magnet. I suppose that the force exerted by one magnet is ...
2
votes
0answers
56 views

Gauss' Law and Electric Field Close to a Ball

So I've learned about Gauss' law and I have something in my head. Why does electric field that is very close to a ball is not close to infinity. Take a look at this image: As we can see, if we make ...
2
votes
1answer
155 views

Periodic ground state 1-dim ising model

Good evening! I'm at the beginning of my study about the Ising model and it has been proposed to me this problem: Find all periodic ground-state configuration for the following one-dimensional Ising ...
1
vote
0answers
32 views

From $\gamma$ to $\sigma$, finding proper basis

For $d$ dimensional case, usual gamma matrices have basis $\Gamma^A = \{1, \gamma^a, \cdots \gamma^{a_1 \cdots a_d}\}$ (Let's think about even case only for simplicity, I know for odd case only up to ...
1
vote
3answers
69 views

Ricci scalar for Black Hole

What is the value of Ricci scalar at $r=0$ inside Black Hole? Since $R_{\mu \nu}=0$ is vacuum solution and valid outside event Horizon of black hole where there is no mass energy density. But inside ...
2
votes
2answers
143 views

Reference frequency

In my experiment, I have to obtain a relation between magnetic field of a solenoid and the applied Vp-p. The setup is as follows. http://www.teachspin.com/instruments/faraday/ Does my choice of ...
3
votes
3answers
286 views

Dummy variables in Dyson series

In the Dyson series, it is known that: \begin{align} {\cal T}\exp\left[-\frac{i}{\hbar}\int_0^tH(t')dt'\right] &= I - \frac{i}{\hbar} \int_{0}^{t} dt' H(t') + \left(-\frac{i}{\hbar}\right)^2 \...
-2
votes
0answers
24 views

Electric Field around Uniformly Charged Rod [on hold]

Question: A uniformly charged rod (length = $2.0~m$, charge per unit length = $3.0~nC/m$) lies on the x-axis. In consultation with your lecture notes, calculate the magnitude of the electric field at ...
-2
votes
0answers
23 views

Which optics should be used for a long range optic until around 800-1000m? [on hold]

I am planning in making a optics for long ranges to see up to 800-1000 meters. With a magnification of 10x-20x. How could I calculate the details of the objective lens, its diameter of tube and the ...
0
votes
2answers
31 views

Forces on body above body moving at constant velocity [on hold]

Let's say the system is moving at constant velocity. What are the forces applied on B? Is there a static friction force? I find it hard to imagine what is happening to object B. $\Sigma F$ is $0$ on A ...
10
votes
4answers
1k views

Hot water freezing faster than cold water

This question has puzzled me for a long time. There is already a question like this on Physics.SE. John's answer to the question seems quite satisfying. But when I googled the cause I found this and ...
0
votes
0answers
17 views

Charge balance and Bogoliubov quasiparticles

Before trying to understand charge imbalance in superconductors (eg Hübler et al., Phys. Rev. B 81, 184524, Quay et al., Nature Physics 9,84–88 (2013)) I thought I had better check I understand the ...
2
votes
2answers
496 views

Kepler's laws to determine radius of circular orbit

"In nonrelativistic limit of general relativity there is a correction to the Newtonian gravitational potential energy $−h/r^3$ with $h = αL^2/(mc)^2$, where $c$ is the speed of light, $α = GMm$ and $...
24
votes
4answers
1k views

What is the status of Mpemba effect investigations?

There is this puzzling thing that is called Mpemba effect: paradoxically, warm (35°C) water freezes faster than cold (5°C) water. As a physisist, I've been asked about it several times already. And I ...
2
votes
2answers
22 views

Charge distribution on a conductor surface

I understand that if a conductor was charged with a charge of say 1 coulomb, the charge would spread uniformly over it's entire surface to neutralize any difference in potential. However, and though ...
9
votes
3answers
501 views

Can a planet form before the parent star ignites?

I'm unable to find an answer to my questions via my searches. This questions pertains to the timeline of a star system creation. My question: During the creation of a star system, can satellite ...
0
votes
1answer
168 views

Is there a mathematical relation between the volume of a speaker diaphragm and the intensity of sound it produces?

I am trying to find out how speaker cones of different diaphragm volumes will produce a certain intensity of sound. Is there a relation that could be used after the volume of the cone has been found?
0
votes
1answer
31 views

Effect of test charge on electric field intensity

Obviously on the macroscopic scale, having a test charge being a proton produces no noticeable change in the electric field produced by a charged body. However, on the microscopic level this would ...
0
votes
1answer
23 views

Power factor effects and causes

Why do power utilities impose power factor penalty when power factor goes low (less than 0.7)? Why does the power factor get smaller when the load is much less than the max or rated power of ...
1
vote
1answer
39 views

What is absorption rate of WiFi and Bluetooth RF in water? [on hold]

Specifically, frequencies 5.75GHz and 2.4-2.485GHz. I want to place a hermetically sealed circuit at the bottom of a gold fish bowl, and want to know if the water will significantly attenuate WiFi or ...
0
votes
1answer
28 views

Retrograde Watches [on hold]

I am not a physicist and not familiar with physics that much.I have a watch which has Retrograde motion. I have read about what is ...

15 30 50 per page