-8
votes
0answers
43 views

What a physicist can work in after the graduation? [on hold]

What a physicist can work in after the graduation? if you ask : what is the branch in physics he graduated from! i say give me a view in every domain. thanks
-1
votes
0answers
22 views

Basic Thermodynamics: Adiabatic Process

we know that for adiabatic process $W=-\nabla E$. My question is here why do we consider $W=nC_v\nabla T$
1
vote
1answer
19 views

Reynolds Average Navier Stokes equations and turbulence scale

To obtain the time average of an unsteady term like $\frac{\partial u_{i}}{\partial t}$ by definition we perform the following: \begin{align} \overline{\frac{\partial u_{i}}{\partial t}} &= ...
-1
votes
0answers
10 views

Energy Transfer Equation - Geothermal water energy [on hold]

I'm a student of Integrated Water Management, so not physics trained, but attempting to solve this question with your help. I have a bore with geothermal water exiting at an average annual ...
1
vote
0answers
19 views

Given a VEV how can I compute which generators remain unbroken using tensor methods?

This is a follow up to this question. A generator $T_a$ of a given gauge group $G$ remains unbroken after some Higgs field $\Phi$ gets a vev if $$ T_a \langle\Phi\rangle =0 $$ I'm trying to ...
-7
votes
0answers
29 views

Why two bodies won't attract each other? [on hold]

Two bodies cannot attract each other as a body contains mass and mass is a constituent of atoms and molecules,held by electrical force.The electrical force is too weak to attract other objects. And ...
0
votes
1answer
19 views

How does a bulb light up when it's connected in a circuit with an uncharged capacitor and a cell?

Since there is a capacitor, isn't it an incomplete circuit? How does the current flow across the dielectric medium? If a bulb was connected to a cell alone and if there was a break in the wires of the ...
1
vote
1answer
43 views

Dark matter configuration

We live in a 3D world comprised of 4 dimensions, if you include time. The unit of spacetime as we "see" it is the proton, comprising of 6 quarks, fermions. Hence since these quarks cannot occupy the ...
0
votes
1answer
25 views

Origin of pressure gradient in Navier-Stokes integral

I am not understanding the origin of the second term on RHS of momentum conservation equation (cf. the Wiki page), $$ \frac{\partial}{\partial t}\int_V\rho\mathbf u\,dV=-\oint_S\left(\rho\mathbf ...
0
votes
1answer
30 views

Can electromagnets repel?

So I saw a video here https://www.youtube.com/watch?v=wzXRFp0DDrU (See the full video first) I don't understand that how is the electromagnet repelling things in the second half of the video? Also ...
0
votes
0answers
12 views

What's the difference between two types of diaphragms?

What's the principal difference between aperture iris diaphragm and field iris diaphragm?
0
votes
1answer
13 views

How are smoke cells an example of Brownian motion?

I don't get how smoke cells are an example of Brownian motion.
0
votes
2answers
28 views

Stern-Gerlach: Why is it probability 1/2 for cooked up silver atoms?

Why does cooking up silver atoms in an oven give them equal probability spin up and spin down?
1
vote
1answer
15 views

Moving coil through space

Programmer here, I have simple question about existence of magnetic field relative to the coil, when moving in space. Imagine we have coil L, that is connected to battery / power supply and coil is ...
2
votes
3answers
55 views

Einstein's principle of equivalence; Standing on earth vs sitting in accelerated car

When I am seated in a car that is accelerating in a particular direction I could, for example, throw a ball and it would appear to be flying the opposite way. With the windows covered etc. An ...
4
votes
2answers
97 views

Is there a phase transition for degenerate matter?

Does electron or neutron degenerate matter undergo a phase transition? Are there any thermodynamic quantities that are discontinuous?
1
vote
1answer
24 views

Drag force acting on a disk in a 2D system

I have a 2-dimensional system with behavior governed by Langevin dynamics in which disks (circles) move through a fluid. In the Langevin equation, there is a velocity-dependent term that accounts for ...
0
votes
3answers
84 views

Why is this method valid in special relativity

Here is the question Two clocks are positioned at the ends of train of proper length $L$. They are synchronised in the train frame. The train travels past you at speed $v$. It turns out that if ...
2
votes
0answers
18 views

Is there a resonance within the earth, separate from the Schuman resonance?

In a very recent biography of Nikola Tesla by Bernard Carlson, the author explains that Tesla measured the resonant frequency of the earth using his invention - the amplifying transmitter. Tesla came ...
0
votes
1answer
38 views

Why do different phases of matter coexist?

Say at a critical temperature $T_c$ there is a phase transition. If we had water, $T_c$ for the liquid-solid transition is $0 ^\circ$C. If we left a block of ice at $1 ^\circ$C for a bit, it will ...
0
votes
1answer
74 views

What is causing the Trumpet Sounds that are emited from the sky?

In these last years, a phenomenon have appeared in several countries (US, Canada, Australia, Russia, Germany, and others). It consists of sounds like a trumpet coming from our own planet's sky. ...
0
votes
0answers
9 views

Show that the electric dipole term vanishes for a particular current

I'm interested to show that given a ring with radius a where there's a current $I_0 \cos \omega t$ ($I_0$ is a constant) there is no radiation due to the electric dipole term (appearing in the ...
0
votes
0answers
34 views

Efficiency of a compressed air engine

I am doing some personal research on the efficiency of compressed air cars. I am currently trying to come up with an 'ideal' cycle to use as a reference for efficiency (c.f. Otto Cycle for petrol ...
1
vote
1answer
43 views

How does a world line of an Alcubierre drive look like?

In my recent question ”Speed of light and warp drives in general relativity” I asked exactly how an Alcubierre drive worked and exactly what "FTL travel" meant. One of the comments I got stated that: ...
0
votes
0answers
19 views

Does RF have any non-orthagonal properties?

Quantum Key Exchange takes advantage of the fact that observing a photons polarization will alter it's polarization. This, along with some tricky back and forth, allows two people to exchange data ...
0
votes
1answer
15 views

Does “converge” mean intersecting and producing image when we are taking about convex lenses?

After reading the chapter on convex lens, I saw several places where "converge" is used. In the very beginning of the chapter, my book says "converging lenses bring light together". So I thought ...
1
vote
1answer
67 views

What is the frequency of the color black?

Our eyes don't see light; they detect vibrations in the 400-800 THz range that we call color. Since our eyes can detect the color we call black, what is its frequency?
22
votes
2answers
1k views

What is the smallest distance possible between two stars?

If two stars of any type were to form near each other, how closely can they form before something prevents them from being two distinct stars?
0
votes
1answer
22 views

Accounting for the thermal excitation in the Richardson-Dushmann equation or the work function equation

When accounting for thermal excitation in a system that is not in thermal equilibrium, heat is constantly flowing through a material, should I account for the thermal excitation in the work function ...
-5
votes
0answers
49 views

Concerning infinite energy and the speed of light [on hold]

From Wikipedia: "Under the special theory of relativity, a particle (that has rest mass) with subluminal velocity needs infinite energy to accelerate to the speed of light, to accelerate beyond the ...
0
votes
3answers
36 views

Drag force - dimensional analysis

I have tried the following example from the link: MIT OCW 8.012 PS1 It is about dimensional analysis. Derive an expression for the drag force on a ball of radius $R$ and mass $M$ moving with ...
-2
votes
0answers
21 views

Magnetic field at focus of parabola [on hold]

A parabola in $x$-$y$ plane carries current $I$, find the magnetic field at the focus of the parabola. Assume focus is at the origin and the focal length of parabola is $d$.
16
votes
1answer
565 views

Is an electron a superconductor?

A superconductor has zero resistance. What about an electron in a vacuum? Could this simple system be considered superconducting?
1
vote
3answers
106 views

Why does Hamiltonian follow the property $H^*_{ij} = H_{ji} $?

I was reading Feynman's Lectures III's Hamiltonian Matrix. There I found this property of Hamiltonian Matrix: The Hamiltonian has one property that can be deduced right away, namely, that ...
-1
votes
0answers
29 views

How do you make a diagram for this vector problem? [on hold]

Question: The simple sum of two co-initial vectors is 16 units and the vector sum is 8 units. The resultant of the vector of the vectors perpendicular to the smaller vector. Find the magnitude of the ...
-1
votes
3answers
68 views

What exactly produces gravitational force? It just can't emerge out of no where depending on mass, distance etc

I tried getting the answer from the internet but it says that it is still a mystery.
0
votes
3answers
42 views

Wavelength vs Wavenumber etiquette

When am I supposed to use the terminology of EM "wavenumber", instead of "wavelength" (or frequency)? The concepts of wavelength and frequency are no problem for me, but wavenumber (number of ...
1
vote
0answers
48 views

Why is SiO2 solid while CO2 is a gas? [migrated]

I was under the impression that chemistry almost exclusively involves valence electrons because there isn't enough energy to strip off electrons further in. If that is true, and atoms in the same line ...
1
vote
0answers
33 views

The derivation of the irreducible representations of the Lorentz group

I took the way of classification of Lorentz group representations from Sexl, Urbantke, Relativity, groups and particles (Germ. ed. 1975). But I don't understand it as I outline in the following: In ...
1
vote
1answer
39 views

How a paper plane(rocket) flies in air? what is science behind it? [on hold]

What factors helps a paper plane to fly and can you explain how these factors help the plane to fly?
-2
votes
0answers
13 views

What is the wavelength of the light and how far away from the central maximum are the first and second maxima? [on hold]

A single, monochromatic light source is shined through an etched, flat prism with a slit separation of 0.025mm. The resulting interference pattern is viewed on a screen 1.25m away. The third maximum ...
0
votes
1answer
72 views

How is angular momentum conserved?

A uniform vertical turntable (mass M and radius R center O) is at rest on the xy plane and is mounted on a frictionless axle, which lies along the vertical z axis. I throw a lump of putty mass m with ...
0
votes
0answers
20 views

Magnus effect, Coanda effect, and the Bernoulli principle: What is balancing gravity on a spinning sphere vs. a stationary screwdriver?

I've seen videos of golf balls and screwdrivers levitated by a focused air stream. Reading the comments of these videos (and others), I see explanations of the machanics at work and their cause and ...
-2
votes
0answers
18 views

What is the small angle measurement from the central maximum to the first maximum? [on hold]

Two thin slits with separation of 0.0200mm are placed over monochromatic red laser of wavelength 632nm. What is the small angle measurement from the central maximum (zero degrees, in-line with source) ...
2
votes
0answers
28 views

Perturbation theory in second quantization

I am dealing with electron/phonon interaction in QM. In particular, given the Hamiltonian of a solid, $$H=H_{el}+H_{ion}+H_{el-ion}$$ we have that the el-phonon Hamiltonian is treatened ...
-1
votes
3answers
52 views

Figure out the force constant of a spring [on hold]

You are asked to design spring bumpers for the walls of a parking garage. A freely rolling 1200-kg var moving at 0.65m/s is to compress the spring no more than 0.090m before stopping. What should be ...
0
votes
0answers
21 views

Do exotic states of matter have high fusion cross-sections?

The Lawson criterion suggests that a chain fusion reaction will only occur in a confined plasma. Since it's a product of temperature and pressure (or density) a chain reaction would be virtually ...
1
vote
0answers
23 views

Velocity profile of a viscously damped wave

For a test case, I want to determine the velocity profile of a viscously damped standing wave. By linearizing the density ($\rho=\rho_0+\rho'$) and velocity ($ux=ux'$), the continuity and ...
0
votes
3answers
44 views

What is the total internal reflection?

From what I read, it sounds like when a light ray passes from one medium to the other, if the critical angle is reached so that the refractive ray is at 90 degree with the normal, the light ray does ...

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