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9 views

Need Help with Proving Faraday's Law of Electromagnetic Induction with Experiment Results

I have recently conducted an experiment measuring emf over time and magnetic field strength over time as a bar magnet fell through a coil. The magnetic field was measured by pointing a magnetometer to ...
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0answers
3 views

Deriving the bulk-to-bulk propagator for a scalar field in AdS

I'm looking at an exercise in the 2016 TASI lectures on AdS/CFT which says to show that the bulk-to-bulk propagator satisfying $(\nabla_X^2 - m^2)\Pi(X, Y) = -\delta(X, Y)$ is of the form $\Pi(X, Y) =...
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2answers
28 views

Is there any proof that F=-kx?

How do you proof that F = - kx ? And why is there (-) on the formula(?)
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0answers
7 views

Stanley kinematic model controller

I am having problem calculating delta (steering angle). L is the length of vehicle lfw is distance between rear and center of vehicle. eta is the angle between direction of the vehicle and target on ...
-1
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1answer
26 views

We all accept/believe in C. But what happens when light travels away from the center of gravity of a heavy star? Does it slow down?

I'm basically trying to understand a mysterious characteristic of the universe. Why light has to travel at C. I understand and accept that from experiment. Not arguing that it does not. Just saying ...
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0answers
19 views

What caused the particles to move?

I wonder how the movement of the particles began? were they always on the move or was there a cause that set them in motion? Could it be that at the beginning of time, all the particles remained ...
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0answers
12 views

SFR Breeders on Small Mars Moon feasibility

Need help with a topic for a sci-fi book. Basic premise is 200yr in future, mining facility on small Mars moon of Phobos. Power source we would like is an SFR breeder as we think this would be cost ...
0
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1answer
8 views

Calculate power of a solar heater

This week-end I build a small solar heater of 1.2meter by 1.2meter. Basically a closed box with the back painted in black and front cover with a transparent plastic. I trying to know the rough ...
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0answers
20 views

Theoretically, is the possibility of quantum superposition at the macro level possible?

We know that quantum overlap has currently managed to do so in up to 2000 atoms, more and more limits are breaking.
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2answers
22 views

Proof that the momentum operator is hermitian without assuming the wavefunction approaches zero at infinity?

I am currently taking my second semester of quantum mechanics. For a number of proofs in the course, we have used the assumption that the wavefunction goes to zero at infinity. We have simply used the ...
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1answer
23 views

How do i calculate the speed of the ball?

A spring pushes a ball with 10 m/s on this bent track. What is the formula to calculate the speed of the ball in point A and point B. The track is horizontal so there is no g-force and the track has a ...
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1answer
18 views

Magnetic flux through closed surface

I'm having a fundamental problem with Gauss's law for magnetic fields. I understand that what goes in must come out. What I'm having difficulty with is that we are dealing with vector fields measured ...
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2answers
25 views

Proof of continuity of voltage across a capacitor

It is known that the voltage drop across a capacitor is a continuous function of time. This means that, for each instant t0, we may write: V(t0-) = V(t0+) This relationship is very used in the time ...
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0answers
10 views

Can plasma be cooled without turning back into a gas, liquid or solid

I’m trying to construct a theory on if the plasma sword in the halo universe would be possible in the real world. So basically what the plasma sword is it is plasma sculpted into a sword shape by a ...
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0answers
20 views

Is the relativistic time dilation compatible with the gravitational field of a moving massive planet?

Assume that a satellite orbits a massive planet/star at a distance $r^\prime$ away from its center in a circular path in plane $x^\prime y^\prime$. Suppose that the gravitational field is $g^\prime$ ...
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0answers
15 views

When Measuring Altitude for a High Altitude Balloon does Temperature Matter?

When I look at the High Altitude Ballon results from people online that have launched DIY balloons (that have posted their data) I can see that their claimed top altitude (based on the pressure they ...
0
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1answer
28 views

How does one include the magnetic scalar potential in the electromagnetic four-potential?

The electromagnetic four-potential is typically written as $$A_{\mu}=(\phi,\vec{A}),$$ where $\vec{A}$ is the magnetic vector potential, and $\phi$ is the electric scalar potential. Should I want to ...
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0answers
10 views

How to do Inverse Mellin Transform of quark-in-quark Anomalous Dimension

The evolution of quark parton distribution functions (pdf) can be described as a resummation of gluon emissions from scale $Q_0^2 \rightarrow Q^2$ via DGLAP equation (in valence sector): $$ \mu^2 \...
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2answers
38 views

Do photons generate gravitational waves?

I guess I’m trying to understand the difference between a rock orbiting earth, that would radiate gravitational waves. And say a photon orbiting a black hole that is just following a straight line ...
2
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0answers
30 views

Mathematically rigorours formulation of the Bogoliubov transform for bosons

Let $\mathfrak{H}$ denote the Hilbert space describing the single-particle states and $|k\rangle$ denote an orthonormal basis of $\mathfrak{H}$. Let $c_k$ denote the corresponding annihilation ...
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0answers
24 views

What happens to the brightness of bulbs if there is a “bridge” with a bulb connecting 2 branches in a parallel circuit?

The title might be poorly worded but here is a picture: Bulb A & C is the same, bulbs B & D is the same and bulb E is added to the circuit as shown. What would happen to the current flow/...
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0answers
31 views

Isospin and $\Delta$ Production

I have seen the relation between cross sections postulated: \begin{align} \sigma(\nu+p\to\mu^- + \Delta^{++})=9\sigma(\nu+n\to\mu^- + \Delta^{+}) \end{align} Motivated by isospin symmetry. I wanted ...
1
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1answer
20 views

Current in linear combination of landau levels

I’m working through Girvin’s Quantum Hall Effect notes (https://arxiv.org/abs/cond-mat/9907002) And I came across the following problem: It is interesting to note that the exact eigenstates in the ...
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0answers
13 views

Collision Frequency in Liquids

I’m trying to quantify the current produced due to electrolysis of an electrolytic solution. What physical model can I use to determine the mean velocity of each ion species in my solution, taking ...
4
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3answers
80 views

How unique is the length scale picked out by intelligent life?

Our human bodies pick out a length scale (let’s say 1m). How unique is this scale and why did it arise? In other words, how much smaller could humans, or multicellular lifeforms in general, be while ...
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2answers
40 views

Do air-crafts fall when exposed to nuclear radiation?

I don't have a background in physics. However I wanted to ask a question relevant to the Chernobyl disaster. From what I found online the helicopter that tried to release sand to shut down the fire ...
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3answers
49 views

Is the slowing of time with speed exactly proportional to the increase of mass with speed?

This article on time dilation explains how time slows and mass increases with speed. Are they proportional? And is time dilation with a specific speed-mass equal to the time dilation with a ...
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0answers
17 views

What keeps a swinging rubber ball in a horizontal circle above head from falling? [duplicate]

If i swing a rubber ball above my head in a horizontal circle, there will be centripetal motion and force but only in X axis,what keeps the rubber ball from falling since there is only one force ...
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0answers
27 views

Confusion regarding derivation of euler's equation

I'm having confusion regarding the derivation of Euler's equation for rigid bodies. Suppose I have an inertial frame $O$, and a rotating frame $O'$ fixed to the rotating body and the rotating frame ...
0
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1answer
21 views

Superposed simple harmonic oscillators

When deriving the equation for the superposed amplitude: $$A^2=A_1^2+A_2^2+2A_1A_2 \cos(\phi_2-\phi_1)$$ From $$x_1(t)=A_1 \cos(\omega t+\phi_1)$$and $$x_2(t)=A_2 \cos(\omega t+\phi_2)$$ How do you ...
0
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1answer
45 views

What if I keep holding a household battery?

I have a question in my mind. What if I keep holding a Duracell(1.5V Battery) touching both the terminals with my fingertips? Will the circuit be completed and the battery drain? Or will it have no ...
1
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2answers
28 views

What happens to the symmetry after gauge fixing?

Given a theory with gauge symmetry. After gauge fixing where does the symmetry go? Does the gauge symmetry turn into a global symmetry? For example there is a way to quantize fields theory with BRST ...
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0answers
15 views

How the variation of Gauss Bonnet term is done?

I am trying to do the variation of Gauss Bonnet Invariant which is $G=R^2+R_{abcd}R^{abcd}-4R_{ab}R^{ab}$ and having problem in doing the variation of $δ(R_{abcd}R^{abcd})$. Can anyone please give ...
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0answers
22 views

Johnson-Nyquist Noise and the Assumption of a Noiseless Load

I'm a little stuck on a subtlety of RF/microwave design that I find a bit baffling. It has to do with the convention of using of noiseless resistors as loads in circuit noise analysis. I have not yet ...
3
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1answer
79 views

Motivation for tensor theory of gravity

In class we were shown that $$\rho = \frac{dm}{dV}$$ has the transformation properties of the 00 component of a rank 2 tensor. So we'd like to turn the classical Poisson equation for gravity into a ...
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0answers
60 views

Quantum Mechanics And Cauchy-Riemann Equations

A complex valued function in complex variable $z$ can be used to represent the potential and field lines of the electric field in 2 dimensions: Some notes on the method of Conjugate Functions This is ...
-1
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0answers
10 views

Demonstration of equation for frequencies in stationary wave in attached ropes (with different mass density) [on hold]

Need help with this problem: Consider a rope with fixed length $L$ subdued to a tension $T$. The rope is made out of 2 pieces of rope of length $L/2$ and mass densities of $\mu_1$ and $\mu_2$ ...
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0answers
18 views

Density fluctuations of the present Universe with Large scale structures

Disclaimer The question below is based on a vague knowledge, and hence, statements can be potentially wrong or misleading. An important quantity in Cosmology is the density fluctuation of matter ...
2
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0answers
19 views

How to understand long-range propagate without decay in time and space?

Assume there is a Green function: $$G=\frac{1}{(p^2+r)-\sum-\omega^2}$$ where $\sum$ is self-energy. We know that if the self-energy vanishes, the quasi-particle is well-define, and it can propagate ...
2
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1answer
41 views

Why is time-evolution unitary - The Heisenberg-picture Version

There are various versions of this question already on this site, which attempt to justify / make plausible that the time evolution of quantum mechanical observables is unitary. Most of these ...
0
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0answers
15 views

How does a phase shifter for an electron beam work?

It is well known that if we insert a phase shifter behind one of the slits in a double slit experiment, the interference pattern gets altered. In mathematical terms this follows because only one ...
0
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0answers
29 views

Particle physics and quantum numbers

Elementary particles contain many quantum numbers which are usually said to be intrinsic to them. If we see a particle that has a same mass, charge and spin of an electron could not be an electron if ...
3
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1answer
59 views

How can electrons and quarks be composite?

There are theories suggesting that the electrons and quarks are not elementary particles, but instead are composite particles of two or more yet undiscovered elementary particles. However ...
0
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0answers
33 views

In the circuit the switch was in position 1 for a long time and at t=0, it is thrown to position 3. Find current as function of time t after switching

I started solving the problem by finding the steady state current. Then as the switch was shifted to position 3 the current in the inductor would decay. But my teacher told me that the current ...
1
vote
1answer
21 views

Heat definition in isotherm and first principle of thermodinamic

We know that the heat Q can be computed by $Q=cm\Delta T$ and in a phase change by $Q=Lm$ (L latent heat). In isotherm process and with no change of phase we can't use those formulas and there's no ...
0
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3answers
57 views

A Contradiction in work done or work energy theorem?

Suppose there exists a Force $F$, acting on a body, which is initially having a velocity $v$, in a direction opposite to that of it's motion. Let the point of application of force produce a ...
0
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0answers
8 views

Scalar Potential Boundary Conditions in Magnetic Diffusion

The magnetic diffusion equation, $$ \frac{1}{\mu\sigma}\nabla^2 \vec{H} = \frac{\partial \vec{H}}{\partial t}, $$ in one dimension is written, $$ \frac{1}{\mu \sigma} \frac{\partial^2 H}{\partial x^2} ...
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0answers
36 views

Field values of a single particle

This question relies on assumptions from my other question How do quantum field values combine? Depending on the answer to that question, maybe this one is not valid. I consider a free real scalar ...
1
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2answers
58 views

What do we understand by a force being central?

Gravity is said to be a central force. But the resultant force field of multiple bodies is no longer central as it has many attraction points. My Doubts: Is the idea of a force being central ...
2
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0answers
19 views

Gravitational wave energy fluxes and bracket averaging notation

Typically the rate of energy loss due to gravitational waves is given in the form (e.g. MTW or Eq 33 of these notes), $$ \dot{E} = - \frac{1}{5} \langle \dddot{I}_{jk} \dddot{I}_{jk} \rangle$$ where ...

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