The classical theory of electric and magnetic fields, both in the static and dynamic case. Also covers general questions about magnets, electric attraction/repulsion etc. Distinct from electrical-engineering.

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1answer
64 views

What is the difference between the Lorentz force and the ponderomotive force? [closed]

I understand that Lorentz force is due to motion of moving charged particle in a magnetic field, and I imagine that ponderomotive force is mechanical version analogy to a person surfing on a wave ...
1
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0answers
37 views

Wind turbine design question [closed]

I am planning to design a wind turbine that is has rotor blade radius of 0.915m and is connected to a generator. The generators specifications are, it is an ac generator with 5000 coil turnings and a ...
0
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0answers
66 views

Insert a Metal Bar Into a Solenoid

This is the question: Consider a solenoid connected to DC power supply such that magnetic field is pointing out of the solenoid on the end that is facing you. A metal bar about 50% longer ...
0
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0answers
43 views

How can the energy of a spinning black hole be converted into magnetic field?

I've read about the Blandford-Znajek process, and what I understood is that the black hole is treated as if it were a conducting sphere spinning rapidly with an accretion disk around it, and the ...
0
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1answer
38 views

Finding the direction of the magnetic field acting on protons in a cyclotron?

I have been trying to answer part b) of the question below: (The image is the image of the cyclotron in question) To find the direction of the magnetic field acting on the protons I tried using ...
3
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2answers
215 views

Aharonov Bohm Effect Interaction Energy Interpretation: $\vec E_m = -∇Φ - D\vec A/Dt$?

The Wang paper "An experimental proposal to test the physical effect of the vector potential" proposes an experiment to decide between two interpretations of the Aharonov-Bohm effect: “the ...
1
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0answers
24 views

Is frictional heat just electromagnetic interactions creating infrared radiation?

Example: Rub your index finger on a sheet of paper and you will feel that it will get noticeably hotter Is the reason you feel this increase in heat (technically an increase in kinetic energy of the ...
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0answers
19 views

wave propagation modelling

what is the best modelling technique for modelling mm-wave propagation in electromagnetic environment. Right now,am working on how to use use Transmission-line matrix (TLM) and ray-tracing techniques
0
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1answer
74 views

“Why electrons don't fall into nucleus”simple explanation needed [duplicate]

Am studying in 8th grade and I studied electrostatic force which says opposite charge attracts and same charges repel But in an atom electron is just situated above the proton and it doesn't ...
0
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0answers
39 views

Magnetic field of rotating charged insulating loop

A charged insulated square loop of side length $a$ is rotated about an axis perpendicular to its plane. What is the ratio of the magnetic field in its centre to the magnetic field of a rotating ...
2
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0answers
38 views

Schwinger metals?

Consider an electromagnetic field that does reach values above the Schwinger limit inside a region of space $R$, on each oscillation. Once the field exceeds the Schwinger intensity, the field causes ...
1
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1answer
35 views

How to relate sunlight's incidence to its E and B amplitudes? [closed]

If I understand this correctly sunlight (as any light) is an EM wave. This means it has, for most mediums, two perpendicular plane waves, an electric and a magnetic, right? We know both are linearly ...
6
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1answer
100 views

Hamiltonian and Energy of a charged particle in an Electromagnetic field

The Lagrangian of a charged particle of charge $e$ moving in an electromagnetic field is given by $$L=\frac{1}{2}m\dot{\textbf{r}}^2-e\phi-e\textbf{A}\cdot \textbf{v}$$ where $\phi(\textbf{r},t)$ is ...
1
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1answer
52 views

When you push a stick will the end of it respond later than the beginning? Is so what is the fastest material and what forces are involved?

Normally when two people hold a long stick the receiving person would feel at the same time the stick moving when the first person gives the stick a push. But is that in reality exactly the case? ...
0
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2answers
34 views

Why do cathode rays bend towards a positively charged plate? Please be a bit elaborate in the answer [closed]

I need help in this quite basic question. Your answers should be bit elaborate and make the concept clear to understand.
0
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0answers
17 views

Ion Source Design

I want to design a DC arc discharge ion source but I can't find a good book that explains how to do it. Can anyone please recommend me a book or paper that explains this? thanks
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0answers
18 views

What is needed to be taken into consideration when measuring torque in dynamic mode?

Let's consider a DG generator connected with a hydraulic turbine through a shaft. To the stator of the generator it's attached a arm connected to a load cell. The load cell is measuring the force that ...
0
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0answers
18 views

Analytical derivation of photonic bandstructure in photonic crystal

It seems the usual way to find the photonic bands of a photonic crystal is to setup the "master equation" $$\nabla\times\left(\frac{1}{\epsilon(\mathbf{r})}\nabla\times\mathbf{H}(\mathbf{r}) ...
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0answers
12 views

High frequency behaviour of copper

Will copper behave as a dielectric in high frequencies???.....I tried to answer the question with loss tangent but relative permittivity of copper posed a problem....everyone on internet opines ...
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0answers
17 views

Magnetic Force of an Electromagnet

If we increase the intensity of the current while the number of turns remains constant, what will happen to the magnetic force? Will it become stronger, weaker, larger etc..?
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0answers
9 views

Hysteresis and magnetostriction

What is the difference between magnetostriction and hysteresis loss. Transformers usually mAke noise due to fact that during magnetization sheets extend itself but when magnetization taken away it ...
0
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0answers
14 views

How to Calculate the force between two different cylindrical magnets?

What happens to the formula when the two magnets aren't identical in height? One is a tiny neodymium magnet and the other is a longer electromagnet. Both are the same width but not height. Thank you
1
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1answer
42 views

Which procedure is correct? [closed]

A problem is given in my textbook pg.no-191 as Example 5.10 A solenoid has a core of a material with relative permeability $\mu_r=400$. The windings of the solenoid are insulated from the core and ...
1
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0answers
21 views

Armco iron B-H curves [closed]

I've been looking for B-H curves for Armco iron. I'd love to find one with good resolution. Does anyone know where you could acquire one? I've been looking in various Armco ingot supplieres but no ...
0
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0answers
32 views

Electrostatic potential due to angular dependent spherical charge distribution

Problem: Given the charge density $\rho = \rho_0 \frac{r}{a}\sin{\theta} \sin{\phi}$ for $r<a$, and $0$ for $r>a$, calculate the electrostatic potential. Issue: I have previously done a ...
4
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2answers
144 views

Missing Hypothesis in Electromagnetism Texts

In the Feynman Lectures, Chapter 21, I find the statement We have solved Maxwell's equations. Given the currents and charges in any circumstance, we can find the potentials directly from these ...
1
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1answer
66 views

The Physics Behind Lint in My Belly Button

Every morning, I wake up, go into the shower and find that I have a piece of lint in my belly button. Now I've looked at this link which does a good job at explaining this phenomena: ...
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0answers
56 views

How does the introduction of a new ground affect a circuit?

I was talking today at lunch with a friend about getting shocked by a light socket while changing a light bulb the other day. The glass got separated from the metal threads where the positive and ...
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0answers
26 views

Image charges and image-image interactions

Say you have 2 point charges (labelled R1 and R2) above a perfectly conducting flat surface. To fully treat this system using the method of image charges (labelled I1 and I2) should interactions ...
0
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1answer
54 views

What is the direction of magnetic lines of force inside a bar magnet? [closed]

So basically , we all know the direction outside the magnet its from NORTH to SOUTH. but what i don't understand is that what is the direction inside is it the same ??
0
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0answers
18 views

Polarization current introduced by induced charge?

Should we count the current density that introduced by the movement of induced charge as free current or magnetized current or neither? And why?
0
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0answers
27 views

Shape of a current carrying wire

Suppose we have an arbitrary shaped wire carrying a current and placed on a frictionless table. What will be the ultimate shape of the wire and why? (Is there any magnetic effect?)
0
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1answer
41 views

Cavity resonator modelling and simulation of em fields inside the cavity

I want to model a cylindrical cavity resonator and study the different modes of em fields inside it using MATLAB/COMSOL. Please refer me books/articles or other resources so that I can achieve my ...
0
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0answers
15 views

does boiling point and surface tension has relationship?

Surface tension arises only from the cohesive forces between the similar molecules at the free surface & the molecules inside of a fluid and Boiling points also changes as inter molecular force ...
0
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0answers
22 views

Impedance of transformers

What does mean by impedance reflecting? Why this phenomena occur? What does mean by Zl=zs to gain max power but power is constant in transformers?
0
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1answer
26 views

Does the magnetic flux spin in the same direction when the electric field is growing and collapsing?

I have three concentric iron pipes, stacked inside each other. It looks like a bulls-eye when viewed from above. To the innermost and outermost pipes I have connected a battery through a switch. ...
4
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0answers
11 views

Is the Poynting vector non-zero when two magnets are placed on either side of a charged capacitor? [duplicate]

I charge up a parallel-plate capacitor, and put a bar magnet on either side, such that the magnetic field is perpendicular to the electric field. S = E x B Do photons start coming out of the ...
0
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1answer
38 views

Changes of Electric fields with motion

I have seen a website which is in Russian language and they expressed that the electric force line will bend along a axis if the charge keep moving, which will be looked like this: But could you ...
1
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1answer
64 views

Magnetic Field in parallel plate capacitor [closed]

A parallel plate capacitor of area 60cm^2 and separation 3mm is charged initially at 90 micro coulomb. If the medium between the plates get slightly conducting and the plate loses charge initially at ...
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0answers
29 views

Why doesn't electricity and magnetism distort space as well? [duplicate]

I think Kaluza/Klein was partly worked on to find additional dimensions to account for electric and magnetic fields. I am confused why the gravity field gets the privileged spot of distorting ...
0
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1answer
26 views

Induced end and monopoles paradox

It states that induced end is equal to the change in magnetic flux but we also know that magnetic flux is zero as magnetic monopoles don't exist so how can flux change?
0
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0answers
33 views

Why you need at least two conductors for Transverse electromagnetic (TEM) propagation in a waveguide?

Do the two conductors have to be separated (no current flowing) or 2 connected lines? Of course both connected to a generator? Thinking about the Maxwell equations I guess the 2 conductors are ...
3
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3answers
86 views

Magnetic force between moving charges

Given two infinite parallel charged rods with equal charge density $\lambda$. They are moving with same constant velocity $\vec v$ parallel to the rods. Find the speed $v$ for which the magnetic ...
0
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0answers
44 views

Magnetic monopole in arbitrary dimension

Assume we have D-dimensional space-time in spherical coordinates $(t, r, \theta_1, ..., \theta_k)$. We have Maxwell equations for $k$-form $F^{\alpha_1, ..., \alpha_k}$ $$\partial_{\mu} F^{\mu ...
0
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2answers
43 views

Electromagnetism - finding electric field from magnetic field

I'm trying to solve the following question, but to no avail. Let $B=\left(0,B_0\left[1+\sin(kx+\omega t)\right],0\right)$ be the magnetic field of some electromagnetic plane wave. Find the ...
0
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1answer
25 views

will the magenet become weightless when made float on super conductor?

will the magnet actually become weightless when floated on superconductor "on specific temprature--ie: in super conductive mode" or it actually has its weight but only seem to be floating due to the ...
1
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1answer
73 views

Some questions about gauge theory

Let's talk quantum mechanics. I have a charged particle moving on a sphere. It has a wave function $\psi$. At time $t=0$, there is no magnetic flux piercing the sphere. Instantaneously, I introduce a ...
1
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1answer
27 views

Eddy currents of a thin wire vs. a large plate?

In many examples such as this: I noticed that most cases where Eddy currents are of focus, or have a considerable effect, would be with examples having a large conductive area perpendicular to the ...
1
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1answer
49 views

Can you measure a motor torque using a load cell connected to the stator? how? [closed]

I saw a picture here: https://measurementsensors.honeywell.com/techresources/appnotes/Pages/Ways_to_Measure_the_Force_Acting_on_a_Rotating_Shaft.aspx It shows a motor casing connected to a load ...
0
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1answer
29 views

Why don't ferromomagnetic domains align with one another?

When a ferromagnetic has never been placed in a magnetic field what is stopping the domains within it from aligning and forming a permanent magnet? The reason I ask is because it seems that ...