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
219 views

What prevents this magnetic perpetual motion device from working? [closed]

Two days ago, I thought of this device, which may seem to rotate indefinitely(in all 3 directions). I have two questions. Is this perpetual motion machine already known? If it is, could you please ...
0
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0answers
38 views

Magnetization of the source due to a stronger induced magnetic field?

Considering this classical diagram: From the top view, we can see a current carrying wire( flow of current is into the page) while an exterior magnetic field($B$) is applied perpendicular to it, ...
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2answers
148 views

Could I make a magnetic foam or film by mixing magnetic dust?

I'm a developer and tinkerer more than an academic, and I'm not sure if this question, being more practical and less theoretical, will be welcome or not here. But here goes, with apologies in advance ...
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2answers
2k 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
78 views

Levitation using Electromagnets - Forces

Here is a hypothetical (but potential real) situation: I am holding electromagnet that weights 1kg. This electromagnet is being used to hold up a 10kg weight. Would I feel like I am holding 11kg, or ...
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1answer
694 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 ...
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1answer
12 views

Magnetically shielding an actuator

We need to magnetically shield a solenoid that activates this valve (shown below) Just slipping a mild steel cap over the end does not do the job, nor appears to have any screening effect at all. ...
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0answers
14 views

How does High mu metal block a magnetic field?

Fran De Aquino suggested VLF currents would trigger a mass shift in high mu metal. But my question is how is a magnetic field actually blocked in high permeability metal?
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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 ...
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1answer
63 views

Is it possible to strip the magnetic, or electric field from a photon?

A photon is made up of a magnetic part and an electric part, but we can see the existence of these fields without the other one so I would like to know if it is possible to somehow separate one field ...
2
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2answers
177 views

How to calculate earth's magnetic field by time period of suspended magnet?

Assuming that torsion of the suspension wire small enough to be neglected, how can we derive earth's magnetic field by measuring time period of an oscillating magnet suspended on a string?
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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 ...
2
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3answers
67 views

Questions regarding magnetic fields and magnetic field lines

I went through certain statements regarding magnetic fields and M.G lines which I am not able to understand. First doubt: Why do magnetic field lines form closed curves? I went through some ...
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2answers
173 views

Direction of H and B inside and outside a bar magnet

I seem to have encountered a contradiction when thinking about the directions of $\textbf{H}$ and $\textbf{B}$ inside and outside a bar magnet. Suppose that a bar magnet has a roughly constant ...
5
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2answers
442 views

Proof of Ampère's law from the Biot-Savart law for tridimensional current distributions

Let us assume the validity of the Biot-Savart law for a tridimensional distribution of current:$$\mathbf{B}(\mathbf{x})=\frac{\mu_0}{4\pi}\int_V ...
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1answer
54 views

Will moving a magnet through cupped hands change the nerve signals through the hand?

Basically nerve signals are electric impulses travelling from the brain to body parts. What would happen if we move a magnet through cupped hands. Would it somehow interfere with the current of the ...
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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 ...
3
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1answer
41 views

Which quantity is independent of others? [closed]

My textbook quotes that:pg.no-190 The three quantities $X,\, U_r$ and $U$ are interrelated and only one of them is independent. Given one, the other two may be easily determined. Where ...
3
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1answer
148 views

Which is more fundamental: $H$ or $B$? [closed]

According to Wikipedia, $B$ is called the Magnetic flux density / Magnetic induction / Magnetic field, while $H$ is called the Magnetic field intensity / Magnetic field strength / Magnetic field ...
2
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2answers
21 views

Inductor circuit

Consider a inductor circuit with an inductor connected to a DC battery and a switch. Initially the switch is open. At time $t=0$ the switch is closed. What will happen to the inductor just after ...
0
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1answer
59 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 ??
3
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2answers
53 views

Why do all magnetic field of a bar magnet do not start and end only at pole?

Iam very confused that why not all field lines emanate out of a pole? Why few field lines emanate and in middle of a bar magnet as shown in the following figure:
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0answers
24 views

Stabilizing a shaft with only one electromagnet

I have recently come across Earnshaw's theorem in my research which states that it is not possible to stabilize an object using only static permanent magnets. I understand that and it makes sense to ...
2
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1answer
402 views

Force on permanent magnet solenoid core

I was wondering, since a coil/solenoid will pull any ferromagnetic material inside it, does the initial magnetization of the object in question affect the magnitude or direction of the force? I know ...
1
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1answer
80 views

Creating a Magnetic Monopole through a torus [duplicate]

Could you create a magnet in shape of a hollow torus and magnetize it so that the interior is south and the exterior is north in order for it to act as a monopole? Is that possible? Thanks
2
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1answer
39 views

How to get speed of a train without using GPS

How can I measure instantaneous speed of a train in which I am travelling without using GPS/location services? The train can start underground or can start from ground level (where GPS is available) ...
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3answers
102 views

Why doesnt magnetic and electric field lines collide?

Why cant they meet or cut each other. I know magnetic field lines dont intersect with magnetic field lines and electric field lines dont intersect with electric field lines but why dont these ...
4
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1answer
129 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, ...
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1answer
27 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. ...
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1answer
124 views

How does the electrons' magnetic dipole moment get influenced when electrons are moving through a magnetic field?

How does the electrons' magnetic dipole moment get influenced when electrons are moving through a magnetic field? How does the electrons' intrinsic spin influence the direction of the electrons' ...
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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 ...
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 ...
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1answer
31 views

deflection of compass and rest position through Magnetic induction

I found a problem with a compass and a magnet, as diagrammed below. The needle of the compass was oscillating, but when a soft iron bar was placed in the "X" then the needle came to rest. Why did ...
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0answers
13 views

Force on a coil threaded by a magnetic conductor - independent of cross section of conductor?

I have a coil that surrounds (but does not touch) a small section of a ring of material with high permittivity. At the other end of the ring there is an attached magnet such that the ring forms a ...
0
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1answer
48 views

Magnets and magnetic Poles

If I take a cubical and spherical magnet where would its north and south pole be, which law governs this or is this simply a matter of probability? Also if I cut a bar magnet by its diagonal where ...
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2answers
64 views

Putting a capacitor into a strong magnetic field, will this change the capacity?

I'm wondering, does a magnetic field change the number of electrons, placed and displaced on the two plates of a capacitor. To prove or disprove this, I think the capacitor could be connected to an ...
8
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1answer
3k views

Wi-Fi in the presence of very strong magnets?

A friend of mine claims to have been able to surf the Internet without fuss on a Wi-Fi connection while performing NMR on samples he was analyzing. I would have thought the strong magnets needed for ...
0
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2answers
47 views

What causes the pattern you see when you hold a strong magnet near a CRT TV?

When you hold a powerful magnet near an old-style CRT TV, you see an interesting pattern, which "shows up the field lines" (see ...
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1answer
182 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
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2answers
130 views

why the shape or size of Magnetosphere is different both side?

Two days ago, I watched a documentary about solar flares, and how Magnetosphere protect us from that to earth. I was able to understand most of it, but I'm still curious to know why the ...
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5answers
87 views

How is the electromagnetic field made?

I know that an electric field is created by a particle with a charge and that a magnetic field is created by a moving charge but how do they combine to make a electromagnetic field?
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0answers
66 views

Unexpected Reading of a Galvanometer in a Transformer [closed]

Last week in physics class, we did an experiment to determine using DC current how to increase the deflection of a galvanometer that is connected to the secondary coil of a transformer. The appartus ...
16
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6answers
15k views

Where do magnets get the energy to repel?

If I separate two magnets whose opposite poles are facing, I am adding energy. If I let go of the magnets, then presumably the energy that I added is used to move the magnets together again. However, ...
3
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1answer
40 views

Magnetic field around a current carrying conductor

Would the magnetic field produced by a current carrying conductor be greater or smaller if the conductor is a bundle of small copper wires or a single, larger rod - assuming the same voltage? ...
6
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2answers
7k views

Why is the divergence of a magnetic field equal to zero?

We know due to Maxwell's equations that: $$\vec{\nabla} \cdot \vec{B}=0$$ But if we get far from the magnetic field, shouldn't it be weaker? Shouldn't the divergence of the field be positive? If ...
0
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0answers
14 views

Can a magnetic field affect the streaming current in high velocity water?

When you flow water at high velocity through a pipe you get a streaming current close to the pipe surface. If you were to then apply a large magnetic field across this pipe (perpendicular to the ...
0
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3answers
4k views

How to demagnetize a magnet temporarily?

How to demagnetize a magnet temporarily? Is it possible making a permanent magnet demagnetize for a short span of time? Or at least long time but temporarily!
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0answers
55 views

Electric field inside the “Dees” of a Cyclotron and why no “Cups”

I read about cyclotron and how does it work. Several references say that the particle to be accelerated is only accelerated when it is between the gaps of the "Dees" or the semicircular disc like ...
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2answers
45 views

The Strength of the Tangential and Radial Components of a Dipole Magnetic Field

I am following along well several textbooks (Geophysics) that helps me understand the in-depth physics behind the magnetic field of a dipole magnet. I understand that the basic magnetic potential ...