For questions that utilize the concept of magnetic fields (commonly denoted by the letter B), or for questions whose answers likely involve magnetic fields. More specific than the [tag:magnetism], as questions about the phenomenon & theory of magnetism do not necessarily involve the discussion of ...

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1answer
26 views

Does the Earth's magnetic field sort cosmic rays by charge?

The Earth is struck by both negative and positively charged particles. As these particles interact with the Earth's magnetic field they become deflected. Do the magnetic poles of the Earth receive ...
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0answers
18 views

Dipoles in an external rotating field?

Consider a bunch of magnetic dipoles in $x-y$ plane in an external magnetic field $B(t)=B_0 \hat{z}+B_1(\cos\omega t~\hat{x}+\sin\omega t~\hat{y})$. The dipoles are rotating around $z$ axis and of ...
0
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2answers
110 views

Magnet dimensions for 3-phase permanent generator

I'm making a 3-phase permenant generator. According to Faraday's law, the emf produced is negative number of turns times the change in magnetic flux over the change in time. If it is only the CHANGE ...
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1answer
78 views

Find magnetic field in a solenoid for different regions?

A steady current I flows along an infinitely long hollow cylindrical conductor of radius R. This cylinder is placed coaxially inside an infinite solenoid of radius 2R. The solenoid has n turns per ...
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4answers
20k views

How does Hendo hoverboards achieve the self-propelling motion? What is the MFA?

From what I understand of the idea behind Hendo hoverboards, they use four disc shaped hover-engines to generate a self-propelling motion. I also understand that it uses Lenz's law and eddy currents. ...
1
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1answer
1k views

Would two Neodymium magnets stick together with twice the power?

Assume I use a coil to create B-flux and put ONE Neodymium cylinder magnet (1" diameter & 0.25" thick) close to the flux, it would create 10 lbs of force. Does that mean that putting TWO cylinder ...
0
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1answer
126 views

Explanation of force amplification inside a solenoid

For a system being actuated by a motor, the force can be amplified by gearing. The energy is being used for force instead of distance, so it produces more torque but moves slower. For a system being ...
0
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2answers
132 views

Are magnetic orbits possible?

I have a small ball with lots of magnets embedded in it with all the north poles facing out and I have a big sphere with lots magnets embeded in it with all the south poles facing out. I set the ...
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0answers
36 views

Verification of Lenz's law in magnetic induction

So the device is a Galvanometer. According to the Lenz's Law, when we take the magnet towards the coil, the pole at the right end, should be north pole and when we take it away, the pole should be ...
0
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1answer
193 views

Right hand rule confusion

I have a question that I am trying to figure out: Two long parallel wires placed side-by-side on a horizontal table carry identical size currents in opposite directions. The wire on your right ...
-2
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0answers
14 views

Magnetic field due to closed donut [on hold]

How to find magnetic field due to a torroid? Thanx in advance. Im studying for jee and our prof tried to teach it but i didnt understand.help please
8
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2answers
492 views

What is the mechanism by which magnetic fields do work?

I've seen some conflicted answers to this question in texts and on the web, in the case of a dipole, for example. Do magnetic fields do work directly, or is it their induced electric fields that do ...
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0answers
6 views

Magnetic field lines for perpendicular current carrying wires [on hold]

Given two straight current carrying conductors, carrying the same current I kept perpendicular to each other. What would the magnetic field lines look like?
1
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1answer
93 views

Prove that Laughlin's 3-electron states are a complete set of states

In R. B. Laughlin's 1983 Physical Review B article, Quantized motion of three two-dimensional electrons in a strong magnetic field, Laughlin separates out the center of mass motion of the electrons, ...
0
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0answers
12 views

Is Earth's magnetic field moving? [on hold]

Is the Earth's magnetic field moving? Why is the Earth's magnetic field said to be moving?
3
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2answers
87 views

What are diamagnets and paramagnets?

A paragraph in my text reads: An atom or ion with all electrons paired is not attracted by strong magnets and is termed 'diamagnetic'. In contrast, spins do not cancel when unpaired electrons are ...
0
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1answer
44 views

What makes B-field not be arbitrarily large very close to an electric conductor?

Assume an inifinitely long, straight thin electrical conductor with current I. It follows from Ampere's law that the B-field intensity is proportional to 1/r, where r is the distance from the ...
1
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1answer
2k views

Force from solenoid

I'd like to approximate the force from a solenoid, or at the very least find a formula which is proportional to the force so that I can experimentally find the constant for my particular case. ...
0
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5answers
108 views

How do magnetic field lines cancel outside of a solenoid?

Please explain me briefly, how magnetic field lines cancel outside solenoid? There is only one wire wrapping it and therefore only one direction of current so how can magnetic field cancel out? How ...
3
votes
1answer
241 views

Could the Faraday's rotating wire experiment be explained without using Lorentz force?

I read Faraday's rotating wire experiment which resulted in the invention of the homopolar motor. He was clever enough to think it that way and make the wire rotate around one of the poles of the ...
1
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1answer
385 views

Peierls substitution vs minimal coupling

In the presence of vector potential (let's assume it's uniform), a tight-binding Hamiltonian will be changed according to the Peierls substitution: $t_{ij}c_i^{\dagger}c_j \to ...
1
vote
1answer
48 views

Why in electrostatics is dV=-E.dr but in electromagnetic induction, EMF=+E.dS?

In electrostatics we learned that dV=-E.dr. I understood the derivation which was used to derive this. Now when I have come to Electromagnetic Induction,I see that when there is a time varying ...
-1
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1answer
9 views

Is the retentivity of soft iron more than that of steel?

Permanent magnets must have high retentivity and high coercivity and steel is used as one. So it should have higher retentivity.
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0answers
6 views

Diamagnetic Sphere Moving through Solenoid

I've seen the videos of frogs being levitated due to diamagnetism. What happens if the frog (or another diamagnetic object) enters a solenoid with an initial velocity? Specifically, consider a ...
1
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1answer
38 views

Entropy reversal in magnets

Entropy is an irreversible phenomenon without any energy supplied to reverse it. I was reading about paramagnetic substances and how dipoles align inside them on application of magnetic field. My ...
4
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1answer
264 views

Boundary conditions on current carrying wire

I'm trying to simulate by finite elements method Maxwell equations for a current carrying wire. My 3d geometry consists of a cylinder and a box containing it. I will use a mixed formulation and ...
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0answers
26 views

Calculating the force applied by an electromagnet on a ferromagnetic object

I know how to calculate the force applied on a magnetic object by an electromagnet at $n$ metres distance using $$F = \frac{(N \cdot I)^2 \cdot k \cdot A} {2 \cdot g^2},$$ but how would one calculate ...
0
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1answer
2k views

How can a magnet have a greater magnetic field strength than a bigger, heavier and more powerful magnet made of the exact same material?

Here are some informations I found on the magnetic field strength (also called "magnetic flux density" or "magnetic induction", commonly denoted as B and expressed in tesla or in gauss) of an average ...
3
votes
4answers
92 views

Positive work by a magnetic field

Consider a single charge moving only under the influence of Magnetic Field $\vec{B}$. The charged particle moves in a circle and the work done by $\vec{B}$ is 0. Now consider a current element in a ...
5
votes
2answers
687 views

Why are magnetic field lines perpendicular to the surface of a ferromagnetic material?

It is known that magnetic field lines become nearly perpendicular to the surface of a ferromagnetic material. The quantitative proof which uses the boundary condition requires that magnetization at ...
0
votes
1answer
108 views

Pulling a bar through a magnetic field

This is a question on magnetic flux and induced voltage. I believe that this problem's answer key is incorrect, and I want to determine whether my opinion is sound. I also want to explore one ...
3
votes
1answer
113 views

Do magnetic fields cause ionisation of gases?

I am doing my final year engineering project on Magnetic Field Assisted Combustion and was curious to see what people thought about it. Companies sell rare earth magnetic arrangements to be attached ...
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2answers
1k views

Why magnetic field lines and force are not orthogonal with magnets?

The below explanation why magnetism exists is superb in this video. The explanation about magnets is also great in this video. A magnet has atoms with unpaired electrons forming mini magnets. The ...
0
votes
3answers
58 views

Does a magnetic field disentangle an EPR pair?

The spins of the both electrons of an EPR pair are undetermined before one conducts a measurement on one of them. Does a magnetic field determine (set up or down) the spin of one partner of an EPR ...
0
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2answers
94 views

Magnetic Force Confusing Paradox

Actually I had posted a very similar question, but I wasn't quite satisfied with the answer so I am posting a new variety again. Imagine an infinitely long wire carrying current $I_1$ from West to ...
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0answers
22 views

Could the assumption of superconductivity explain unexplained geomagnetic behaviors?

Science recently published an article regarding a new discovery in superconductivity; that the metallic form of hydrogen sulfide is superconducting at high temperature (relative to absolute zero). ...
0
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2answers
168 views

What determines the magnitude of force of an electromagnet?

Let's assume that there is an electromagnet with $B = 1 Tesla$ , what is the magnitude of the force it could generate on other dipoles equal to it's surface area? Can the magnitude of force (in ...
5
votes
2answers
52 views

Earth's magnetic field shields us… from what threat?

This is a nice artistic picture of the magnet field of the earth, shielding us from the solar wind. (source) Wherever you look, it is stated that without our shield, life would not be possible on ...
1
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1answer
86 views

The strength and control over the strength of electromagnets, correlation between the strength and weight of the magnets

I am currently working on a project that aims to use the attraction & repulsion between two electromagnets as an alternative to weights, from a physiotherapy and rehabilitation perspective to help ...
0
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1answer
15 views

Does resonant inductive coupling work in the presence of a strong magnetic field?

Does resonant inductive coupling work in the presence of a strong magnetic field? I am unsure because resonant inductive coupling uses magnetic fields to transmit power wirelessly and a strong ...
2
votes
2answers
68 views

Showing that the magnetic field inside an infinite current carrying cylinder is zero

I'm doing some self studying of introductory physics, and was working a question from a textbook that has several parts. The first few parts asked me to show that the magnetic field of an infinite ...
1
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1answer
248 views

Calculating the magnetic field from rectangular conductor?

I want to apply the Biot-Savart law to calculate the magnetic field at a point created by current flowing through a square/rectangular conductor. More specifically, a trace on a printed circuit board. ...
0
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2answers
83 views

Most fundamental quantity in magnetostatics and magnetodynamics [closed]

In both elctrostatics and electrodynamics, the electric charge is defined as the most fundamental quantity. What is the most fundamental quantity in case of magnetostatics and magnetodynamics ?
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1answer
26 views

Sequential Stern-Gerlach devices - realizable experiment or teaching aid?

At least one textbook [1] uses sequential Stern-Gerlach devices to introduce to students that the components of angular momentum are incompatible observables. Viz., the $z$-up beam from a SG device ...
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0answers
14 views

How to divert water flow by magnetic field or static electricity or electricity?

Is it possible to make a magnetic or electric plate that prevent hitting water to itself or at least divert it? Which force is most effective, magnetic field or static electricity or electricity?
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1answer
976 views

Do really, two oppositely charged bodies (of equal charge in magnitude) attract each other?

It is well known fundamental behaviour that, oppositely charged bodies attract each other (I don't know whether it applies also for charges of equal magnitude or not), and identical charges repel each ...
11
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1answer
108 views

What causes the sharp borderline at the bottom of northern lights?

The northern lights are caused by cosmic charged particles interacting with the earth's upper atmoshphere. The particles can be trapped by the Lorentz force, so that we can see them where the magnetic ...
0
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1answer
367 views

Magnetic fields in transformers and back emf?

i am having some trouble with understanding the magnetic fields inside transformers and how they relate to back emf. My first query is: is the magnetic field produced inside the soft iron core ...
0
votes
1answer
100 views

What is the magnetic flux density “outside” the solenoid when AC current is passing through it?

I know that there are well defined equations explaining the magnetic flux density in the solenoid. However what about magnetic field outside the solenoid? How is the magnetic flux density related ...
0
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3answers
62 views

Rate of Acceleration of an Object Pulled by Magnetic Force

Gravity on earth pulls objects toward it with an acceleration of 9.8 m/s/s on Earth until the object reaches it's max potential free fall speed. (I call this terminal velocity though I think that this ...