1
vote
1answer
54 views

Choice of sign of exponential argument affecting tractability of wave reflection at a boundary

It is possible to show that functions of the form $f_{1}(kx-\omega t)$, $g_{1}(kx+\omega t)$, $f_{2}(\omega t-kx)$ and $g_{2}(\omega t+kx)$ are all solutions of the wave equation ...
3
votes
1answer
73 views

Three-body correlation function in kinetic theory

In Kinetic Theory, one studies the evolution of a system of $N$ particles interacting with each other. We use the notation $\boldsymbol{w}_{i}$ to describe the coordinates in phase-space of each ...
6
votes
2answers
515 views

DIY Quantum Eraser Experiment by the Scientific American: Is this really quantum?

Click here for the publication. Having performed this experiment, I have gotten clean results. Essentially, a double slit is made by putting an photon beam in the way of a wire with orthogonal ...
2
votes
2answers
19 views

Wave displacement with phase difference 180

The variation with distance x along a wave of its displacement d at a particular time. A second wave has the same frequency and speed as the wave shown in Fig. 2.1 but has double the intensity. The ...
6
votes
3answers
131 views

Jupiter radiation belt: where >MeV particles comes from?

When I read some discussion about exploration of Jupiter moons, or possibility of life there, a common argument is high dose of radiation in Jupiter's radiation belt (several orders of magnitude ...
2
votes
3answers
181 views

Probability density of electron orbital

Why the probability of density is higher in the area that is closer to the nucleus? I'm a high school student. I don't know much about wave functions.
0
votes
0answers
38 views

Why does my metalic water bottle make noise? [on hold]

I have metallic water bottle from Mountain Warehouse. An image of it is below. I fill it up and take a couple of swigs and I hear these random clicks and ticks after I set it down and other noises ...
1
vote
1answer
16 views

Questions about the formula used to determine inductive reactance and $Z_t$

I am currently on the inductors unit in my Navy schooling and I have two questions about these formulas that I learned about. As I'm aware, the ability of an inductor to concentrate a magnetic field ...
0
votes
1answer
83 views

Outcome from this experiment with solid hydrogen?

Let's say that we have two solid hydrogen blocks (or at least two solid hydrogen lattices) in a vacuum. Both blocks have perfectly smooth surfaces which are later put together. Before putting blocks ...
-4
votes
0answers
15 views

Principle of electrical machine by vk R mehta complete ebook needed [on hold]

I need the ebook for my exam on Wednesday(expecially dc generator and dc motor chapter)
31
votes
4answers
4k views

Are atoms unique?

Do atoms have any uniquely identifying characteristic besides their history? For example, if we had detailed information about a specific carbon atom from one of Planck's fingerprints, and could ...
0
votes
1answer
491 views

holographic projection in thin air?

from where I come from ,they taught us in high school that it is possible to project holograms in thin air simply by illuminating the hologram with the "correct light" , and having a semi transparent ...
1
vote
0answers
24 views

How does independence of the basic bras affect the choice of numbers used to represent a ket?

On page 54 of Dirac's book, The Principles of Quantum Mechanics, he states: Take an orthogonal representation with basic bras $\langle\lambda_1\lambda_2...\lambda_u|$, labelled by parameters ...
0
votes
0answers
7 views

Extracting times of hits from a composite detector response

I have a detector that registers a sequence of "hits" over a period of time. Each hit produces a signal that has the approximate form ...
2
votes
1answer
40 views

Finding potential energy of a solid hemisphere on top of another solid hemisphere [on hold]

A solid hemisphere with radius $b$ has its flat surface glued to a horizontal table. Another solid hemisphere with radius $a$ rests on top of the hemisphere of radius $b$ so that the curved ...
0
votes
1answer
33 views

Gravitation Field inside hollow sphere [on hold]

for this homework problem I am trying to work out the gravitation field inside a hollow sphere. I have searched for a while now and haven't found a good post working it out thoroughly. One thing I ...
1
vote
0answers
39 views

Tensor Notation Puzzle

I have hesitated to ask this question for fear of someone tagging it as a duplicate. It comes close to what others might have asked but I am looking for particular answers to this puzzle. Using ...
0
votes
1answer
29 views

Deriving electric field

Can anyone explain where the following expression for the electric field vector comes from? $$ \mathbf E(\mathbf r,t) = -\nabla \phi(\mathbf r,t) - \frac{\partial}{\partial t}\mathbf A(\mathbf r,t) ...
8
votes
3answers
245 views

Do two photons traveling in opposite directions emit gravitational waves?

Do two photons traveling in opposite directions emit gravitational waves? If so, does it mean that any volume filled with photon gas will eventually degrade into graviton gas? In other words, if flat ...
0
votes
2answers
35 views

How do the flow equations relate to the actual situation?

This question might seem silly but I'll try to make it clear. It's a question (I think) about partial differential equations systems in general, but since currently I'm studying fluid mechanics I'll ...
3
votes
2answers
98 views

Is there a way to create a flickering frequency to be dependent on speed of the person looking at it?

Is there a way to make a screen or a road sign flash at different rates, depending on the velocity of the observer looking at it? I would like to achieve a state where two observers going at ...
1
vote
2answers
174 views

Derivation of the full generator of the lorentz transformations

Let us study the subgroup of the Poincare group that leaves the point $x=0$ invariant, that is the Lorentz group. The action of an infinitesimal Lorentz transformation on a field $\Phi(0)$ is $L_{\mu ...
1
vote
0answers
18 views

Behavior of Parahydrogen in a Magnetic Field

At low enough temperature, at equillbrium, the dihydrogen molecule is predominately parahydrogen, with the spins of the two protons opposite. Does an external magnetic field alter the ortho-para ...
-4
votes
2answers
50 views

What will happen if a hairdryer is turned on in an air tight box?

I wanted to know what would happen if a hairdryer is turned on in an airtight box
1
vote
0answers
80 views

Were Maxwell's equations first formulated by McCullough?

Some years ago, I heard a talk about a an Irish or Scottish physicist named McCullough who had formulated Maxwell's equations several years before Maxwell. This fellow was recognized for his work, ...
6
votes
1answer
741 views

Can you measure the speed of water coming out of a hose by its arc?

Water comes out of a horizontally stationed hose and creates an arc as it heads towards the ground. Can I determine the speed the water was traveling in when it exited the hose by the measuring the ...
0
votes
2answers
5k views

How does current flow from the emitter, through the base and to the collector in a NPN transistor?

So, I understand that for a NPN transistor to work the emitter-base junction needs to be forward biased and the collector-base junction needs to be reverse biased. I understand how current flows from ...
8
votes
4answers
1k views

How fast would someone have to run to travel vertically up a wall?

I am currently doing a physics project on the effects of so-called 'super-speed'.I was wondering how fast you would have to run to vertically travel up a wall? That is, to negate the force of gravity. ...
4
votes
3answers
375 views

Is the concept of (force of ) inertia still useful and used?

The force of inertia is the property common to all bodies that remain in their state, either at rest or in motion, unless some external cause is introduced to make them alter this state. That ...
2
votes
1answer
12 views

Potential energy of Hydroelectric plant before the dam was built

So the energy potential of a Hydroelectric dam is the difference between the head and base. Before the dam was built where does all that energy go? I can understand that for a long valley that is ...
1
vote
1answer
152 views

Earnshaw's theorem and springs

Earnshaw's theorem states that the Laplacian of the potential energy of a small charge moving through a landscape full of static negative and/or positive charges (and gravity) is zero. Thus you can't ...
2
votes
3answers
77 views

Self-energy of electron from classical reasoning

If it takes energy to group charge together(self energy) how can it be possible for every single electrons, etc, to have exactly same amount of charge? (think of if we hold some sand in our hand, then ...
17
votes
4answers
2k views

Trying to combine red, green and blue to produce white

I tried to mimic the mechanism of typical screens to produce white color out of red, green and blue. What I did is displayed the attached image on the screen, and moved far away as to let the ...
2
votes
3answers
44 views

Calculate the flux of a point charge with Gauss's law

I know from my class that to calculate the flux of a point charge with Gauss's law, I have to make a surface that intersects with all of the flux lines resulting from the charge, and then make this ...
2
votes
3answers
80 views

Index notation with Navier-Stokes equations

This is an index-notation question rather then the NS one: For incompressible flow and Newtonian fluid, the continuity equation is denoted with: $$\frac{\partial u_i}{\partial x_i} = 0, $$ which ...
0
votes
1answer
38 views

What molecules are ionized in a lifter ion engine?

Lifters generate lift through ionizing air molecules and then attracting those ions toward an oppositely charged surface to create thrust. are constructed on a balsa frame with a 1 inch wide aluminum ...
2
votes
1answer
38 views

Coupling of matter field with gauge boson and Goldstone boson:

What's the fundamental difference between the way a gauge boson gets coupled to a matter field, preferably a Fermionic field and the way a Goldstone boson gets coupled to the matter field ? In ...
1
vote
1answer
35 views

Can we extract chemical energy remotely?

To state directly. Can we use any electromagnetic method to extract energy from fat? Humanity store useless fat inside their body. And to work out mechanically leads to frustration of tireness and ...
0
votes
0answers
5 views

PEDOT drying and polymerisation on air [on hold]

Have anyone tried to dry and polymerize PEDOT:PPS on air (usually it dryed in dry nitrogen, but we'd like to avoid our equipment modification)? What are the results?
3
votes
3answers
75 views

Forces on objects orbiting a black hole?

Firstly, please excuse my elementary knowledge and lack of eloquence when writing about astrophysics. I am a dentist, who occasionally thinks about the how the universe works. I'm both fascinated and ...
1
vote
1answer
21 views

a charged particle path [on hold]

A particle of mass $m$ and charge $e$ enters a homogeneous and stationary electric field $E$ with velocity $v_0$ perpendicular to the direction of the field. Calculate the particle's path? What does ...
6
votes
1answer
121 views

How would one experimentally prove AdS/CFT correspondence?

What would be an experimental test of AdS/CFT correspondence? Or it's extensions? I've heard that people are studying AdS/CMT (condensed matter) correspondence, but I don't know the details of it? ...
11
votes
2answers
2k views

What if photons are not the fastest particles?

Einstein originally thought that special relativity was about light and how it always travelled at the same speed. Nowadays, we think that special relativity is about the idea that there is some ...
6
votes
2answers
94 views

Gauge choice after Spontaneous Symmetry Breaking

After the spontaneous breakdown of local symmetry in presence of gauge fields (Higgs Mechanism), we can always choose a gauge where the Goldstone bosons are eaten up by the gauge field (also called ...
1
vote
1answer
16 views

Can iron be magnetized Via electric current in aqueous solution?

If you suspend iron particles in water and run an electric current through, the particles gather in a line along the current. Is this a form of magnetism?
3
votes
1answer
54 views

Why does matter gather as discs around massive objects? [duplicate]

Why do discs, like rings of Saturn and the spiral shape of our galaxy form around massive objects, instead of just a (spherical?) cloud of matter?
5
votes
2answers
155 views

Why do we need non-trivial fibrations?

I am currently reading this paper. I understand how the Bloch sphere $S^2$ is presented as a geometric representation of the observables of a two-state system: $$ \alpha |0\rangle + \beta |1\rangle ...
5
votes
1answer
227 views

QED Vertex Factor/Rule

On page 303 in Peskin&Schroeder they give the vertex factor as $$V = -ie\gamma^\mu \int d^4x$$ while on page 304 they write $$V_\times = -ie\gamma^\mu\int d^4x A_\mu(x).$$ Why are the ...
2
votes
1answer
83 views

What is the appropriate device for measuring energy loss from collision with surface?

The surface of a running track (i.e. cinder or rubber) has an effect on a runner's performance. I would like to get some device for measuring how much energy a runner loses on each surfaces. I've ...
1
vote
0answers
37 views

How to prove that the net magnetic force in an arbitrary current loop is zero [on hold]

I believe that using Stokes' theorem makes this a laughing matter, because $$\mathbf{F}=\oint_C i d\mathbf{r} \times \mathbf{B}$$ Since the magnetic field is constant the $\nabla$ operator would ...

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