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
38 views

What is the reason behind the shape of the magnetic field lines in a circular loop?

Sorry if this question is stupid, but I really need to understand this. I read that in a straight simple wire, the magnetic field lines are concentric about the wire, and the circles become larger as ...
0
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0answers
67 views

Is magnetic field changing over the distance?

If we take ONE separate magnet, with lines of the magnetic field coming out of north and going into the south. 1) Does magnetic field change along any of those lines? [ 2) If no (that is what I ...
12
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4answers
2k views

Why should Conservative forces have their curl equal to zero?(intuition)

There are several conditions that must be met in order for a force to be conservative. One of them is that the curl of that force must be equal to zero? What is the physical intuition behind this? If ...
36
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4answers
1k views

Is there an underlying physical reason why the Coriolis force is similar to the magnetic component of the Lorentz force?

I couldn't help but notice that the expression for the magnetic component of the Lorentz force, $$\mathbf F = q\,\mathbf v \times \mathbf B\,,$$ is very similar in its mathematical form to the ...
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0answers
33 views

Magnetic field interaction energy term

I am trying to derive the Ginzburg-Landau free energy for superconductors, and I follow most of it apart from the introduction on the term containing the magnetic field. This is the bit I don't ...
0
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0answers
27 views

Net magnetic field & magnetization on a ferromagnetic material

A ferromagnetic materiel is saturated by an exterior magnetic field like so: Where $B_1$ is a uniform magnetic field. Then after some time $t$ another magnetic field $B_2$ is introduced as well, ...
4
votes
2answers
52 views

The direction of magnetic field- right hand rule

My question is, why is the magnetic force going the same way as the fingers, why not the other way. What causes the magnetic field to choose a direction if everything is symetrical
0
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0answers
30 views

What metal can be used as electromagnet core to attract a permanent magnet?

ok. Here are the requirements: 1.The core should not be attracted to permanent magnet when idle(like stainless steel), 2.Should act as electromagnet core with better permeability(like iron). Is ...
1
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1answer
41 views

Why does a magnet loose magnetic strength when heated?

Magnet manufacturing companies, for example Dexter Magnetic Technologies do not hesitate to explain the effects of heat upon magnets - citing how it degenerates the magnetic properties with levels of ...
0
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1answer
33 views

Magnetic field and magnetic domains

I have a confusion regarding how magnetic field propagate in a medium (ferromagnets or air etc..). It is knows when a ferromagnet is exposed to an external magnetic field, the magnetic domain of the ...
4
votes
4answers
21k views

magnetic field outside a solenoid

I couldn't picture the idea behind the zero magnetic flux outside the solenoid properly.My teacher explained it as"Components of the magnetic field in other directions are cancelled by opposing fields ...
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0answers
32 views

Attraction between electromagnet and a permanent magnet - at which point is the force the strongest?

You have an air-core inductor with current applied, so that the magnet in the picture will be attracted to it. At what position will the force between the two be the strongest and at which the ...
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2answers
2k views

Why is a paramagnetic material attracted into a magnetic field?

I want to start by saying I've seen this topic: Attraction and repulsion of Magnetic materials and its supposed duplicates and it hasn't helped me very much. In the book Introduction to ...
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0answers
25 views

Would a spinning carbon steel (high magnetic permeability) sphere become magnetized?

Would a spinning carbon steel (high magnetic permeability) sphere "falling" through Earth's magnetic field become magnetized? Would a spinning, evenly charged sphere generate a magnetic field?
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3answers
42 views

Interaction between magnetic moments and magnetic field

Consider a particle with a magnetic moment $\vec{m}$. For simplicity, suppose that this particle is a circle in the plane $xy$ which can rotate around its center of mass along the $z$ axis. If this ...
-1
votes
2answers
43 views

Electromagnetism on a compass [closed]

A current $2\ \mathrm A$ flows in a vertical wire. The value of the horizontal component of earths magnetic field in the region is $2*10^{-5}\ \mathrm T$. A small compass is placed $5\ \mathrm{cm}$ ...
1
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2answers
46 views

Quantization of the Hamiltonian of a particle in a uniform magnetic field

If a particle of mass $m$ and charge $q$ is subject to a uniform magnetic field and if we have a vector potential $\mathbf{A}$ then we know that classically the dynamics of the particle will be ...
1
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2answers
334 views

Formula for Magnetic field due to current loop

I need expressions for $B$ field off the axis due to current loop. The ones I came across on the internet aren't very convincing. I verified them with Mathematica, and none seems to be correct. I'm ...
3
votes
2answers
30 views

Current loop and direction ambiguity of the magnetic moment

Consider a circular loop in the XY-plane which carries a current $I$. Then it behaves as a magnetic dipole with moment $\textbf{m}=I\int d\textbf{S}$ where $\int d\textbf{S}$ is the area of the loop ...
1
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0answers
20 views

What is a simple model to find the jump height for the Thomson's Jumping Ring experiment?

I'm trying to devise a basic formula that could give a rough estimate for the jump height reached in the Thomson's Jumping Ring experiment, as detailed here. However, it's pretty difficult as most ...
0
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0answers
25 views

Magnetization of the toroid

As far as I understand, bodies are magnetized by orienting electron spinning within the atoms. Once placed into magnetic fields, they align rotation so that they produce magnetic field in the same ...
0
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0answers
23 views

Motion of current carrying rectangular coil in magnetic field

a current carrying rectangular coil is placed in a uniform magnetic field as the plane of coil is parallel to the field at the beginning . assume that there is no restoring torque and no friction. i ...
0
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0answers
30 views

Net magnetic field at a point

Given 5 wires ( $w_0, w_1,w_2,w_3,w_4$) all separated equally by a distance ($r$) from one another like this diagram: Applied a voltage two each wire individually and current flows like so: ...
0
votes
1answer
41 views

Why does the Emf generated by a magnet going through rings of coil generate a sinusoidal curve of Emf vs time?

I am having trouble writing the reason for the part of the curve to cut the x axis at Emf = 0 and when reason for curve to form max and min peaks.
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2answers
105 views

Why do magnetic field lines converge where the strength is strongest?

In most of the sites, they just say that "to determine the strength of the magnetic field, one must look at how many lines are present at a particular location." But my question is why? Why is this ...
0
votes
1answer
36 views

Why should you be careful when you use a Hall effect probe to measure magnetic field?

Question: Why must you be careful with orientation when you use the hall effect probe to measure magnetic field? Background: In a recent Physics 2 lab, we used a magnetic field sensor ...
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0answers
15 views

Magnetic Fields and their strength

1) Does a larger magnetic field make a magnet stronger or extend the range (space) in which it can influence objects? 2) What makes a magnet 'stronger' (have a larger attractive pull)?
1
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1answer
19 views

Which conditions need to be fulfilled for a FODO cell to provide focusing in both planes?

I often come across the claim that a FODO cell can provide focusing in both planes so long as said cells are appropriately configured. I have never come across any elaboration of what this ...
2
votes
0answers
189 views

Graphene - Can it produce a magnetic field?

So it's probably a quick no on this one, but since I haven't majored in physics or chemistry I have no idea if it's possible to make Graphene generate a magnetic field. Assuming power or current is ...
-2
votes
2answers
77 views

It's not the size of your magnet?

Growing up I've seen magnets on the fridge to the cows stomach and the latest that I know of, neodymium. On a molecular level what makes some magnetic material stronger and last longer than others?
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0answers
49 views

Magnetic field of multiple loop turns?

Given this equation to calculate the magnitude of the magnetic field: $B = \mu_0 \frac{N }{l} I .$ Where $\frac{N }{l}$ is the number of turns per unit length. $I$ is the current, $\mu_0$ ...
-1
votes
1answer
225 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
votes
0answers
39 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, ...
0
votes
2answers
81 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 ...
1
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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. ...
0
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0answers
15 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
46 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 ...
0
votes
1answer
67 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
votes
2answers
188 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
44 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
votes
3answers
112 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 ...
1
vote
2answers
208 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
votes
2answers
466 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 ...
0
votes
1answer
56 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 ...
0
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0answers
15 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
vote
1answer
45 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
votes
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
votes
1answer
152 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
votes
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
votes
1answer
76 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 ??