2
votes
1answer
26 views

Colour of ocean water

Why does ocean water seem blue colour in some regions while green in some regions while river of pond water is never blue in colour?
1
vote
3answers
106 views

Is Hamiltonian a differential operator in second quantization?

Normally, a free particle Hamiltonian is written $$ \hat{H} = - \frac{\hbar^2}{2m} \Delta $$ which is a differential operator because Laplacian $\Delta$ is. On the other hand, in second ...
0
votes
2answers
48 views

Rotate a small wheel using magnets

I know this question already asked so much times. I tried to rotate a wheel by placing few magnets on it. And I used some powerful magnet and repel it using opposite poles in the magnets placed in a ...
1
vote
1answer
38 views

Electric field between capacitors [on hold]

A parallel-plate capacitor consists of two parallel, conducting plates of area $A$, separated by a distance $d$. Each carries a charge of magnitude $Q$; positive on one, negative on the other. ...
1
vote
2answers
74 views

Klein-Gordon Green's function: derivative of delta distribution?

In Peskin/Schroeder there is an explicit calculation showing that the retarded Green's function of the real Klein-Gordon field $$D_R(x-y) ~\equiv~ \theta(x^0 - y^0) \langle 0 | [\phi(x), \phi(y)] ...
5
votes
1answer
197 views

Force problem related to adhesive and bonding

I have two PCBs (printed circuit board), and they are glued by adhesives, as show in the pictures. And the location of the adhesives are indicated on the picture (please notice that NO adhesive is ...
-1
votes
0answers
26 views

Density and behaviour of gravity [duplicate]

If a matter condensed into small enough (schwarzchild radius) we can create Blackholes. I have trouble understanding this concept. Does the black hole created for example by compressing a tennis ball ...
0
votes
0answers
43 views

Terminology: Gauge stress?

When a material is loaded with a force, the stress at some location in the material is defined as the applied force per unit of cross-sectional area. If I have a material submerged in pressurized ...
5
votes
2answers
650 views

Could an oscillator at a high enough frequency produce light instead of radio waves?

Considering that light is in the 400-800 THz range, if you had an electrical oscillator that ran at that frequency connected to an aerial of some sort, would the antenna emit visible light, in the ...
0
votes
1answer
47 views

What exactly is closed orbit theory and what assumptions go into it?

I am just beginning a research project on the study of closed orbits, specifically as related to hydrogen, and I wanted a little bit more information on what exactly makes something a "closed orbit". ...
-1
votes
0answers
15 views

Photons absobtion during quantum jump

According to this article a quantum jump CAUSES photons absoptions. Does it mean that if there is no photon around quantum jump is impossible? https://en.wikipedia.org/wiki/Atomic_electron_transition ...
51
votes
11answers
18k views

Is it possible that there is a color our human eye can't see?

Is it possible that there's a color that our eye couldn't see? Like all of us are color blind to it. If there is, is it possible to detect/identify it?
0
votes
0answers
29 views

Distribute force over a rod

Well, the idea is that I have a rod of length $L$ and force $F_0$. Now I have to distribute those $F_0$ Newtons on the rod. But the problem is, that I want to do it continuously. So what I want in the ...
0
votes
0answers
22 views

concerning the effects of temperature and density on the speed of sound [duplicate]

here is my relatively broad question: how does the temperature and density of a medium effect the speed at which sound travels through it? Now I shall elaborate: it is my understanding that there ...
0
votes
2answers
51 views

What's the max speed a man-made satellite can travel in space before its circuitry stopped working?

Assume it could withstand extreme temperatures in either direction. I'm mainly curious what would happen to its circuits as it approached the speed of light.
4
votes
1answer
288 views

Resources for theory of distributions (generalized functions) for physicists

I am looking for tutorials, articles or books containing theory of distributions in context of mathematical physics. Please suggest.
-4
votes
1answer
36 views

Alka Seltzer Model: formulas/models requested [on hold]

This evening I became fascinated with how my Alka Seltzer tablet disintegrates over time within a small portion of Diet Lipton Citrus Ice Tea. I used a nearly frozen cup; tall, as one might request in ...
22
votes
6answers
3k views

Are there two theories that are mathematically identical but ontologically different?

I have no background in physics but there is a question that has been bothering me, so I'm asking you. Are there at least 2 physical theories that are : Mathematically identical, which means that ...
-3
votes
0answers
115 views

Doping in physics [on hold]

compare and contrast the principle involved in doping and bonding. Why do increase in thermal agitation in semiconductor result in increase in conductivity
1
vote
0answers
27 views

Problem with OPE (from Polchinski) [on hold]

I was reading Polchinski, Vol. 2 pag 12, while I found (10.3.12a): $$ e^{iH(z)}e^{-iH(z)}=\frac{1}{2z} + i\partial H(0) + 2zT^H_B(0) + O(z^2).\tag{10.3.12a} $$ Now I tried to do the OPE, what I ...
13
votes
6answers
3k views

Why do physicists believe that there exist magnetic monopoles?

One thing I've heard stated many times is that "most" or "many" physicists believe that, despite the fact that they have not been observed, there are such things as magnetic monopoles. However, I've ...
2
votes
3answers
86 views

Is it accurate that light loses energy in the absence of gravity and gains energy in its presence?

I just read an article about the supervoid they found and this is suggested. If so, then I am more and more fascinated with the ties between light and gravity. Let me emphasize, every article that I ...
0
votes
3answers
51 views

Do matter and antimatter annihilate or release energy?

Do matter and antimatter eliminate each other or release their equivalent energies? I'm almost certain it's the latter as mass can't be destroyed, but when speaking of the big bang it's said if there ...
2
votes
2answers
89 views

Do atoms behave like waves? [duplicate]

I've heard someone state that the double slit experiment can also be done with atoms, not just electrons or photons of light.
-2
votes
0answers
23 views

Calculating deceleration time - help! [on hold]

I'm struggling with a question due to not having the correct formula, so I hope someone can help! A 10000kg object is travelling at 15m/s, and a force of 600N is applied in the opposite direction to ...
-1
votes
0answers
27 views

Minimum set of theories to rule them all [duplicate]

What is the complete (and minimal) list of theories that wraps everything we know in physics? e.g.: Is General Relativity a superset of Newton's theories, or an addentum? Does quantum ...
3
votes
2answers
117 views

Entropy / Structure Relations

I want to check on the validity of the following objective definition of order. Is it correct? Is there a more rigorous statement of this concept? The further a system is from its maximum ...
2
votes
1answer
238 views

Local minima in Ising model in a Monte Carlo simulation

Is there any way to check whether in a Monte Carlo simulation using Ising model is stuck in any (false) local minima of energy or not, particularly in 3D system ?
-2
votes
3answers
63 views

Is all of the energy dissipated in a magnetic core in the form of heat and can any of it be recovered?

In an AC motor where you use a laminated magnetic core to shield the induction process from eddy currents, the field lines that run through it result in core loss through heat. Is all of the energy ...
0
votes
3answers
105 views

Isn't a physical frame of reference useless for calculating speed?

Please ignore relativistic effects and the effects of the expansion of space-time due to the expanding universe theory for the purposes of this question. Whenever someone asks what is the speed of X, ...
1
vote
1answer
156 views

Induced electric field due to a moving wire

An infinite wire carrying a constant current $I$ in the $\hat{z}$ direction is moving in the $y$ direction at a constant speed $v$. Find the electric field, in the quasistatic approximation, at the ...
0
votes
2answers
62 views

Why is this circuit component on without a potential difference?

From the following graph, determine whether (h) will be on or off: I think (h) should be off because there is no potential difference across it. Is this correct? Edit: Using the method provided ...
1
vote
1answer
74 views

What is a wavelength of an EM wave physically?

This might be a silly question given I am a physics undergrad, but I was suddenly confused. Usually when EM hit a gap they diffract through the gap. But if the gap is too small, diffraction can't take ...
13
votes
2answers
1k views

Is it possible to generalize the Maxwell equations to higher dimensions?

The usual Maxwell equations are for 3 spatial dimensions, right? Is it possible to generalize them to 2 spatial dimensions or 4 spatial dimensions?
0
votes
1answer
81 views

Internal Resistor in a Diode

When we talk about the resistance of a diode (of the P and N region), is this resistance like the one inside an Electro-Motive Force or it acts like a normal resistor (external electric field exist)? ...
0
votes
0answers
39 views

How can I obtain a unit vector of a shifted spherical system? [migrated]

I hope that I can explain myself clear enough, Assuming i have a sphere that has been moved down in the Z-axis. I know that the radial unit vector when the sphere is not shifted can be expressed as: ...
0
votes
0answers
30 views

Does the effect of spaghettification mean that (speculative) traversable wormholes can only exist from supermassive black holes? [on hold]

Assumption that wormholes really exist. Even if humanity could produce wormholes from quantum black holes. These would be never traversable due to the effect of spaghettification? Or does the exotic ...
12
votes
3answers
2k views

Maxwell in multiple dimensions: What happens to curl?

I read this answer a while ago, and while thinking about $\nabla$, I realized something. Since the cross product can be written as a determinant, in higher dimensions we require extra vector inputs. ...
-2
votes
0answers
20 views

thermodynamics question [on hold]

I've thought this question for a really long time and now i need help..... The question is "the volume occupied by a mole of liquid water at 100 degrees celcius is (1.87 exponent -5) cubic metres. ...
-2
votes
0answers
9 views

The velocity of the image if both the mirror and the object start moving [on hold]

Suppose a vertical plane mirror and a object which is placed at a distance of 4 m from the mirror. If we start moving the mirror with a velocity of 2m/s and also start moving the object at 3m/s. Then ...
0
votes
1answer
109 views

Natural frequencies of a torsion system

Find the angular displacement $\theta_1(t)$ and $\theta_2(t)$ of the system shown in figure below for the initial conditions $\theta_1(0)$, $\theta_2(0)$, and $\dot{\theta}_1(0) = \dot{\theta}_2(0) ...
3
votes
2answers
39 views

Topological insulators literature

I started learning things on topological insulators and I got lost in dozens of existing papers on this topic. Could anyone recommend me appropriate literature that explains deeply enough what ...
4
votes
1answer
207 views

Good source for numerical simulations of Wigner function?

I'm interested in simulating the time evolution of a Wigner function for a harmonic oscillator (and possibly some other potentials) and I can't seem to find a good resource for that. My background in ...
1
vote
1answer
205 views

Proton scattering off electrons

I'm looking at a question which starts off as: A proton is travelling through a material and scattering the electrons in the material. Express the scattering angle in terms of the impact parameter, ...
1
vote
1answer
27 views

Gravity's tall box with a ball inside - scenario

Let's imagine we put a ball inside a box such that it doesn't touch its walls, and suddenly drop the box. Because the two objects fall at the same rate of acceleration, the ball will stay at the same ...
6
votes
5answers
2k views

Is the speed of light in vacuum always the same value?

The escape velocity of different planets and stars vary. If they vary, the velocities of bodies escaping from the respective stars or planets should also vary. Like, if I want a ball to reach 10 ...
3
votes
1answer
101 views

Why are nonrelativistic methods used in binary pulsar systems (gravitational waves)?

Although gravitational waves are a subject of the General Relativity, why do most books use Newtonian equations of motion for power radiated and rate of change of eccentricity calculations? In most ...
0
votes
1answer
21 views

how covalent bonding lower the energy of potential energy

Considering the potential energy of interacting particles, how does covalent bonding lower the energy of the system?
0
votes
1answer
203 views

Series / parallel capacitor network: find two capacitances and source voltage given some measured data

Capacitor 3 in Figure (a) is a variable capacitor; its capacitance $C_3$ can be varied. Figure (b) gives the electric potential $V_1$ across $C_1$ versus $C_3$. The horizontal scale is set by $C_3 = ...
1
vote
1answer
111 views

Why do electron and hole mobilities decrease with temperature?

From page 35 of "Microelectronics" by Millman Grabel Mobility $\mu$ decreases with temperature because more carriers are present and these carriers are more energetic at higher temperatures. ...

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