0
votes
0answers
3 views

Why does band gap form for Silicon?

The image on the right shows that as the interatomic distance becomes closer together, the 3P and 3S band that joined together begins to split up forming a gap in allowed energies. Why does this ...
0
votes
0answers
4 views

potential profile in two battery in series

Hi I would like to know the potential profile in two series battery. Simialr as that in the attached image for single battery.
-1
votes
0answers
14 views

Are The Quantum Assumptions of MBT Theory Correct?

I've become very interested in Tom Campbell's MBT Theory (Plenty of YouTube videos). I can't explain it all here because it takes a book (The one he's written). It's based on the virtual reality ...
1
vote
2answers
13 views

Starter's book on Quantum Mechanics (more general and simple books than full QM textbooks) [duplicate]

This question is a little different from other questions referring to books on QM. I ask you to tell me some books that have QM on a simpler level than that of a full course on QM. Some universities ...
0
votes
0answers
9 views

Altarelli-Parisi Splitting Function $P_{qq}(z)$ vanishing integral if and only if quark flavour sum rules and equivalence

Question 1: I believe both questions are in the context of Deep Inelastic Scattering. I've been given the expression for $F_{2}^{ep}(x)=(\frac{2}{3})^2[u(x)+\bar{u}(x)] +(\frac{1}{3})^2[d(x) + ...
-1
votes
1answer
24 views

Can I become an engineer and a physicist? [on hold]

I want to study mechanical engineering. Would that give me enough knowledge to research in theoretical physics?
1
vote
2answers
17 views

Description of charged sphere with Heaviside function in cylindrical coordinates

I need to describe density of charge of uniformly charged sphere (radius R, total charge Q, position of centre (0,0,0)) with Dirac delta function and Heaviside step function. The hard part is to ...
0
votes
0answers
12 views

Help with a couple of materials science questions

My first post on this forum is asking for some assistance in answering some questions. I was hoping as well as being given an answer, you could offer a little explanation so that I can understand - ...
0
votes
1answer
14 views

How to calculate the resultant movement of a superposition of harmonic oscillators?

If $x_{1}(t) = \cos(\omega t - \frac{\pi}{6})$ and $x_{2}(t) = \sin(\omega t)$ are two simple harmonic oscillators in the same direction and with the same angular frequency $\omega$, how to ...
0
votes
0answers
5 views

Can someone explain diamagnetism in plasma?

Diamagnetic plasma has an internal resistance to an outside magnetic field. I thought that a good analogy for this would be electrical resistivity. In high school we learned that different ...
1
vote
0answers
28 views

Is there a black hole map which shows all BH's in our galaxy?

I am looking for a map which shows all black holes in our Milky Way galaxy. See the link of an Exoplanet map for what I mean. http://www.hpcf.upr.edu/~abel/phl/phl_exoplanets_stellar_map.png If it ...
0
votes
0answers
9 views

Model of scattering in wet things

You know that clothes and some surfaces become darker when wet (covered in an earlier question: why wet is dark?), because of the disordered reflections or of the refractive index of water or ...
-1
votes
1answer
16 views

The Electric Quadrupole

I've read the following sentence: "Every electric circuit with two pairs of accessible terminals is called a quadrupole." I was wondering why does it happen that the multipole expansion gives us a ...
0
votes
0answers
15 views

Behaviour of Gases

Gases tend to move from higher pressure to lower pressure, thats fine. But why they are so aggressive in this regard. For example, in vacuum-lifters they are able to lift mass (weight) of up-to ...
1
vote
0answers
18 views

Legendre transform for non-local Lagrangians, or Hamiltonian of non-local Lagrangian and their properties

This is sort of a multi-part question, mostly dealing with how to treat non-local Hamiltonians and how the corresponding properties of Hamiltonians work in a non-local framework. I proposed an example ...
1
vote
1answer
30 views

Force between two finite parallel current carrying wires

Remark: This is not a homework question...It is pure out of theoretical interest. I asked this the mathematics-community a couple days ago and got no answer, so I figured I'd try here. Most standard ...
1
vote
0answers
15 views

Can sound frequency create more ideal conditions for fire?

You may have seen the recent story of a device that engineers claim can extinguish flames using sound frequency. An older article loosely explains the theory behind how this works: Sound travels ...
1
vote
0answers
14 views

Do any, all, or no adjustments to standard model change the Weinberg angle or it’s relation to masses or coupling constants?

Do any, all, or no adjustments to standard model change the Weinberg angle or it’s relation to masses or coupling constants? If any, which (types of) ones? For the ones that do, what are the relations ...
0
votes
1answer
17 views

Experimental evidence for Z boson coupling to right handed fermions

I do have a question about electro-weak interactions. I know the Z boson is an admixture of two fields, one that couples only to the left-handed part of the fermions (the neutral field introduced to ...
0
votes
1answer
11 views

squared position dependent electric field

Here's an asignment problem that got me puzzled. The thing is that I have to solve a second order non linear differential euqation, the course is an urdergraduate mechanics course. A particle of mass ...
0
votes
1answer
23 views

Metric in Lagrangian and the minimum total potential energy principle

I was wondering why physical systems "like" to go to the minimum of potential energy and I found this question, that tries to justify the minumum total potential energy principle. I was also reading ...
0
votes
1answer
8 views

Torque wrench units

My torque wrench has these markings on it: (da. Nm.) and on the line below M. KGS. I can tell from comparing the scale to poundf-foot on the other side that the scale units are kilograms-meter ...
0
votes
1answer
19 views

Why is the lyman alpha line asymmetric at high redshift?

If someone could explain this to me I'd be very grateful, thanks.
0
votes
0answers
8 views

Optics - Photodiodes - minimum photon energy that a photodiode will be sensitive to

I'm foraying into the world of photodiodes, and I'm trying to calculate the minimum photon energy required for the photodiode to be sensitive to. Symbolic expressions desired. Minimum detectable ...
1
vote
2answers
43 views

What does the “T” stand for in T-duality?

First of all, I am not a physicist. I'm a graduate math student and recently I came across the concept of T-duality. Actually I'm studying generalized complex geometry, which according to this paper ...
0
votes
1answer
29 views

Finding magnetic field inside rotating sphere

A sphere with radius $R$ has constant charge density $\rho$ per unit volume. This sphere rotates as a rigid body with an angular velocity of $\omega$ around an axis that goes through the center. What ...
0
votes
1answer
24 views

Entanglement entropy in (1+1)d field theory with dynamical critical exponent $z>1$

It was well known that for (1+1)d CFT(z=1) case, we can use the tool of conformal map to derive the formula of entanglement entropy for a finite interval: S ~ $c \log L$. L is the length of the ...
-2
votes
0answers
30 views

The prevailing electric field problem

Let us consider a charged particle $A$, which is certain to remain fixed at its position. Now let us consider another charged particle $B$, having charge $Q$. Let the electric field at a point $P_1$ ...
0
votes
2answers
34 views

How does Ohm's law relate to transferring energy?

Potential difference = Current x Resistance where Resistance is a constant. Walking through a circuit I have 1 battery, a wire and 2 components. I start of with 6 volts at the battery and after the ...
0
votes
0answers
43 views

Big Bang…or…Everywhere Stretch?

Recently I watched a minute-physics video that suggested that a better name for the beginning of time would be "Everywhere stretch" because there wasn't a space-time singularity that formed where the ...
8
votes
3answers
293 views

Why do lines in atomic spectra have thickness? (Bohr's Model)

Consider the atomic spectrum (absorption) of hydrogen. The Bohr's model postulates that there are only certain fixed orbits allowed in the atom. An atom will only be excited to a higher orbit, if ...
2
votes
1answer
45 views

Propagation speed of photons when taking higher-order QFT corrections into account

In our group of experimental physicist who have nothing to do with and know very little about quantum field theory, we recently had a question concerning the propagation speed of photons in vacuum: ...
0
votes
0answers
19 views

Hadamard Gate application help

I need to prove that if you apply Hadamard gates on the input/output before and after a CNOT gate that you get the same answer as flipping the target and control qbits of a CNOT. So for example I'm ...
0
votes
1answer
31 views

How does the photon differentiate between events?

As far as I know for a photon that's moving at the speed of light (obviously) time comes to a halt and space contracts to a point, making all travels instant from its perspective. Now this is the part ...
0
votes
2answers
42 views

Position space wave function of an electron

In Wikipedia I find the wave function of a free particle to be $$ \Psi(\vec{r},t) = A\,e^{i(\vec{k}\vec{r}-\omega t)}$$ This is is a plane wave moving in the direction of $\vec{k}$ with speed (phase ...
1
vote
0answers
34 views

Virtual particles and the scaling effect on valence quarks

Summary from Carrolls: "Particle at the end of the Universe", page 101. Inside a proton there are 3 valance quarks. In addition, there is constant creation and annihilation of gluon, quarks and ...
1
vote
1answer
25 views

Why is a substrate needed in growing GaN?

Is the substrate a layer on which GaN crystal grows on? Is there a way to grow free-standing GaN? Would the resultant crystal be full of defects?
0
votes
0answers
13 views

Post-measurement state for measurement outcomes on Qutrit states [on hold]

I am trying to do problems in Barnett.S. - "Quantum Information" book but I am confused on what the question wants and how to proceed. The question is as follow, The qutrit (three state system) ...
0
votes
0answers
16 views

Force on charged particle in magnetic field [on hold]

I am having difficulties achieving the answers to a question in my physics textbook. The question goes: A charged particle $q = 3.0 × 10^{–19}\space C$ and of mass $5.65 × 10^{–27} kg$ moves ...
-4
votes
2answers
47 views

Einstein's mass-energy equivalence

Einstein's wonder equation $E=m c^2$,if we take energy is proportional to the mass, we can put single constant to make that equivalent equation. We all know that ...
0
votes
0answers
29 views

Property of helium superfluid [on hold]

I learnt that in helium II every atom would have same wave function and is governed by BE statistics. does that mean all helium II atoms would vibrate in the same way in a field?
1
vote
0answers
28 views

is there any molecular transition which emits a photon in certain direction

i know molecules having magnetic moment would be aligned in certain direction but do they emit photon in any certain direction when excited? are there any molecules which would emit photon in tthe ...
0
votes
1answer
52 views

Is dark matter moving faster than light? [on hold]

My way of thinking is as follows: Consider a balloon. Let this be blown into a nearly elliptical sphere. Now, the temperature inside the balloon is increased by some means; this leads to the ...
-1
votes
0answers
28 views

Force and laws of motion, friction [on hold]

The 12 kg block is put on the 3 kg platform which attached to the wire AB. The friction coefficient between 12 kg and 3 kg platform are ų(s)=0.6 and ų(k)=0.40. Determine the magnitude of acceleration ...
0
votes
0answers
19 views

Calculating tension at every point on rope around pulley [on hold]

Suppose a pulley is fixed over a wall and a rope is passing over it such that both the ends of the rope are connected to boxes having masses $m$ and $M$ ( $m<M$) Assume mass per unit length of rope ...
10
votes
2answers
405 views

In an electron-positron annihilation, in what direction are the photons released?

I read that, in an electron-positron annihilation, at least 2 photons are produced, because of the law of conservation of momentum. my question is: in what direction are those photons released? and ...
0
votes
0answers
19 views

Ice test for F1 cars. [on hold]

i heard that F1 cars has zero traction, i.e., no friction between wheels & ground. but F1 cars undergo ice test beofre they get commissioned. why do they undergo ice test?
1
vote
0answers
23 views

Interpretation of Mass Continuity Equation in MHD

I'm writing up my final-year dissertation and I'm required to give, as part of the introduction, an analysis of all the equations (and their terms) of which I use. Embarrassingly, whilst of course ...
1
vote
1answer
20 views

Electric Dipole force exerted by a charged wire on a dipole

Why is force exerted by a charged wire on a dipole given as $F = P×(dE(r))/(dr)$ where P is the dipole moment? Please explain in simple words and avoid using too much technical derivations.I am a ...
0
votes
1answer
25 views

Conceptualising the switch from discrete molecules to the continuum (fluid dynamics)

I understand that $\rho(x,t)$ represents the density of the small volume surrounding the point $x$. However what have I done with the discrete molecules in the process of averaging?

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