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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How does electromagnetic induction happen?

Electric and magnetic fields are different from each other(i think i am correct).. How does changing magnetic field induce electric current???
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178 views

Is there energy stored when iron is magnetized?

When a piece of iron is magnetized, and the domains are aligned, Is there energy stored? If so, how much energy is stored? If there is an attraction between that same iron and the source of the ...
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1answer
146 views

Question about superconductivity

A long cylinder of radius $R$ is made from two different material. Its radius $r<r_0$ $(r_0<R)$ part is a material with superconducting transition temperature $T_1$, and its $r_0<r<R$ ...
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1answer
91 views

Magnetic deviation of a uniform external magnetic field in the presence of a well-defined iron object

Suppose initially I have a uniform magnetic field. Now, in this formerly-uniform magnetic field, I place an un-magnetised cylindrical body of iron into this field of known dimension, with the axis of ...
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1answer
402 views

Can I Demagnetize a ferromagnet with a hammer?

If an iron is exposed to an external magnetic field, the iron's domains are all aligned with that ext-B . If I strike it with a hammer, will it be demagnetized? Comparing it with heat, I know the Tc ...
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3answers
410 views

Will a ferromagnet retain its magnetic properties after reaching the curie point?

If a piece of iron or any kind of ferromagnet reaches its Tc, it will lose all it's magnetic properties, and will not be affected by an external magnetic field, if it drops back to room temperature or ...
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0answers
119 views

Variation of electric field and current flowing

Theoretically, a change in either electric or magnetic field will cause a current to flow , I am already familiar to Faraday's law of electromagnetic induction, so I tried to search about producing a ...
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0answers
513 views

Rate of change of magnetic flux and the speed of the magnet

The faradays law is $-N*A* \frac{\Delta B} {\Delta T}$ which is the rate of change of magnetic flux times area. How to find out the voltage induced when the magnet moves through the coil and exits ...
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1answer
153 views

Magnetic induction in Relativity

As we know magnetic phenomenon is a mere relativistic effect.My question is how to explain the magnetic induction in a relativistic manner?
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15 views

Is imperative magnetic flux the capacity of individual atoms, or the constituent valency of chemically-bonded molecules within a vacuum?

If magnetic energy depends on the electron poles within two-fields within a permanent magnets void, how do invidiual atoms react within the attraction or repulsion of poles, and what incurrence does ...
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1answer
623 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 ...
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2answers
354 views

Why moving charges causes Magnetic Field (module and direction)?

Why an constant electric current in a wire produces a magnetic field, that circles that wire? I know that this question was posted before. However, all answers talk about Maxwell equations, axioms, ...
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1answer
182 views

Questions on electric field formed in conductor and the magnetice field it moves through

When a conductor (e.g. a wire) is moving through a uniform magnetic field, it will create a electric field in the wire as the magnetic field exerts a force on the moving conduction electrons in the ...
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0answers
118 views

Force of a magnet in a magnetic field?

Let's assume you have a simple bar magnet in a magnetic field. I know that the tendency is for the magnet to line up with the magnetic field. I'm trying to figure out how much force that actually ...
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1answer
242 views

Lorentz Force Law and cycloid motion

The question I have is from Intro to Electrodynamics by Griffiths (Page 206, Example 5.2) http://imgur.com/a/sfBlt When using the initial conditions $y(0) = z(0) = 0$, I get: $y(0) = 0$ implies ...
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2answers
2k views

Non-conservative electric fields due to changing magnetic flux?

What I read in several places, tells me that, the fact Coulomb's Law follows inverse-square law and gives a force which is radial, implies that a static electric field must be conservative.(In short, ...
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1answer
132 views

What's the significance of the definition of T1 and T2 relaxation times

In MRI we measure $T_1$ and $T_2$ relaxation times. $T_1$ relaxation time is defined as the time it takes for the longitudinal component of magnetization to recover $1-1/e$ of its original value, and ...
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1answer
138 views

Magnetic field strength of a hydrogen electron

Does the rotation of the electron around the hydrogen nucleus cause a resultant magnetic field in the atom? If so, the current density must be very high and the resulting field should affect the ...
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1answer
188 views

Uniform constant magnetic field and traditional attractive force

Why uniform constant magnetic fields can not exert net force on a piece of iron whatever strong it might get?
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3answers
2k views

Magnitude of magnetic field at the center of circular wire

I'm preparing for an exam by solving the sample questions , here is the one I'm having difficulty with : Following is the given circuit. Which contains two resistance $R_1$ and $R_2$ in form of ...
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1answer
141 views

Which magnetic force is stronger? Electron or proton?

Assume the particles generates the magnetic field with their own spin. No motions except spin.(they have their intrinsic angular momentum.) Then which one generates stronger magnetic force? I've seen ...
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0answers
584 views

Magnetic field of solenoid in cone shape

I have done some drawings of the magnetic fields of cone shaped solenoid electromagnets. I based this on the work of Tesla and some explanations of Bashar, known as the Bashar Cones. I found very ...
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1answer
325 views

Can an asteroid have a magnetic field?

Some M-type asteroids are believed to be metallic, even possessing Nickel-Iron. Given the proximity of the asteroid belt to Jupiter's magnetosphere, the regularity of motion of any given M ...
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3answers
119 views

Horizontal magnetic attraction?

I came across and interesting effect today, I have a dozen of Neodymium magnets around my house. And, they are very strong. Anyhow, one of them got attracted to my large steel plate table(use for ...
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0answers
236 views

Two magnets with Iron truncated cone or pyramid. How low inclination can the truncated cone or pyramid be made?

Two magnets with Iron truncated cone or pyramid: Frustrum How much low inclination can the truncated cone or pyramid: Frustrum be made, without non homogeneous lines of magnetic field coming out from ...
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1answer
63 views

Energy spent by motor in a period

Consider a single coil that is turning in a constant and uniform magnetic field thanks to a motor. The normal to the coil is given by: $${\bf u}(t)=\sin (\omega t){\bf u_x}+\cos(\omega t){\bf u_z}$$ ...
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0answers
208 views

Infinite long current carrying wire inside a infinite long solenoid

The magnetic field due to a long infinite solenoid is zero outside the solenoid. If there is a long infinite current carrying wire at the axis of this solenoid then The field is non-zero outside the ...
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0answers
60 views

Maximise magnetic force at one point while minimizing at another

Is it possible to have a magnet that attracts one object strongly, but not another object behind that first object? Given an (electro-) magnet M above two thin parallel steel sheets P1 and P2 in the ...
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1answer
163 views

Magnetic field when moving into the influence of a ferrous object

Suppose I have a magnetometer. I am on the Earth's surface, away from the influence of other magnetic sources. Assuming the magnetometer is aligned with the reference frame, it should read only the ...
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1answer
400 views

Pressure experienced due to magnetic force?

A current $I$ flows in a long thin walled cylinder(parallel to the axis) of radius $R$. What pressure do the walls experience? This is the 263rd problem in Section III from the book 'Problems In ...
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1answer
106 views

Magnetic force at the edge?

When sliding a magnet over a ferromagnetic surface there is no magnetic force at all, however,there is a magnetic force only at the edge, when the magnet is being pulled of I assume the magnetic field ...
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2answers
1k views

Could you use earth's magnetic field to build a hover skateboard? [closed]

In "Back to the Future" they use levitating anti-gravo skateboards without wheels which will be difficult to build, because there is no theory on how anti-gravity could be created. A possible ...
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1answer
297 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 ...
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3answers
403 views

The magnetic field of a magnetic monopole

Let us define the magnetic field $$\vec{B} = g\frac{\vec{r}}{r^3}$$ for some constant $g$. How can we show that the divergence of this field correspond to the charge distribution of a single magnetic ...
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2answers
2k views

What prevents this magnetic perpetuum mobile from working?

As a child, I imagined this device, which may seem to rotate indefinitely. I have two questions. Is this perpetual motion machine already known? If it is, could you please give some references? What ...
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1answer
120 views

What are magnetic field lines?

Does a magnetic field have concentrations of magnetic force lines as seen when putting iron filings over top a bar magnet or are these imaginary? I.e. are they just an artifact of the iron being a ...
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1answer
590 views

Calculate Magnetic Flux Density between Two Disc Magnets

If I have two disc-shaped magnets (radius r=0.05m, width w=0.03m, Remanance Br=1.06 T) separated by a distance d, how can I calculate the magnetic flux density somewhere between them? I found this ...
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0answers
162 views

Is it possible to have a magnet which looks like a hollow cylinder and who's north is interior and south is exterior? [duplicate]

Is it possible to have a magnet which looks like a hollow cylinder and who's north is interior and south is exterior? What then happens as the cylinder gets longer? Would that affect the strength of ...
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1answer
380 views

Why are magnetic fields only produced by moving charges? [duplicate]

Why do charged particles only produce magnetic fields while in motion?
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2answers
265 views

accelerated charged particles and interaction with magnetic field

In high school we are taught that magnetic field perpendicular to velocity of an charged particle experience perpendicular force that causes it to move in circular path by relation ...
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0answers
33 views

What is the lifetime of an induced magnetization in a para/diamagnetic material?

To the best of my knowledge thermal fluctuations are responsible for washing out any effective magnetization, once the external field is switched off. Since thermal fluctuations need some time to ...
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2answers
228 views

Cause of electromagnetic induction?

The rate of change of magnetic flux through a surface (open) is related with the line integral over the closed loop binding the selected surface by one of the Maxwell's equation. But that means even ...
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1answer
426 views

Would an octahedral magnet work as a magnetic bottle?

First, let me see if I understand all this: Charged particles are curved by magnetic fields, so if the magnetic field is strong enough, the particles "follow" the magnetic field lines, in N or S ...
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2answers
243 views

Can a magnet magnetise an object with greater strength than it possesses?

Trivial thought ... Materials may be broadly superconductive, diamagnetic, paramagnetic, ferromagnetic. An object is magnetized by repetitive motion of a magnetic field across it's surface Say a ...
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1answer
50 views

How does bow-shock constitute evidence of a magnetosphere?

Several bodies in the Solar System are possessed of a magnetosphere - Sol, Jupiter, Saturn, Earth to name a few. With these we have the proof of spacecraft/readings from Earth. For exoplanets being ...
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2answers
827 views

Is it possible to levitate a toy maglev train using only permanent magnets as long as the train stays in motion?

I am fascinated with magnets, and specifically the idea of magnetic levitation. I recently purchased a Levitron toy maglev train and have enjoyed finding the perfect sweet spot at which it levitates, ...
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1answer
1k views

Work done by magnetic field [duplicate]

I know Lorentz force don't do any work. but I want to know whether any type of magnetic field do a work or not.
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2answers
184 views

Magnetic moment precession around magnetic field

I have a question regarding the magnetic moment of an atom. If you just have one atom, and you apply an external magnetic field in lets say the z-direction. Then the magnetic moment will precess ...
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0answers
146 views

Projects for a physics club [closed]

It's a physics club for undergraduates (first three years of university); I'm looking for projects idea that aren't too obvious like a small rocket or an electromagnet (school projects) but also not ...
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1answer
139 views

Magnet alignment within solenoid

Imagine I have a solenoid connected to a power supply. Solenoid produces an electromagnetic field. Now I take a permanent magnet and place it inside the solenoid. How will the magnet align itself ...