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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Why metal sphere (conductor) is used in Van de graff as the output terminal, not any other material , specifically any insulator?

Why metal sphere (conductor) is used in Van De Graff as the output terminal, not any other material, specifically any insulator?
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30 views

Why don't we see a precession of compass in constant magnetic field?

It is known that spin particles put in magnetic field precess at the Larmor frequency around the axis of magnetic induction B. For example if the spin was perpendicular to B, the spin of the particle ...
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1answer
45 views

Problem with magnetic field due to relative motion

We know that, moving charge produces magnetic field in the surrounding space. Consider this scenario : A charge 'q' is moving with a constant speed 'v' in the direction of positive x axis of a ...
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1answer
26 views

Do Magnetic Solids exhibit their Magnetic properties in their Gaseous state?

Example Does cobalt, a solid exhibit Magnetic properties when converted to its Gaseous State.
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26 views

'Printing' magnetic polarity into a material

There is a company out there that 'prints' magnetic pixels, a.k.a. maxels, into a material. In doing so, they're able to choose the distance of effect of magnetic fields they create, independently of ...
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1answer
44 views

Does a precessing spin in constant magnetic field change the field somehow?

If an electron enters a magnetic field along the lines of the magnetic induction it spin starts to preccess. Suppose the field was made by a coil (toroid). What changes happen in the field - current - ...
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1answer
41 views

Gruchestein Effect?

I overheard that name in a conversation, but not very clearly. I can't find anything on Google, probably because of my spelling is completely wrong. Does anybody knows about an effect with a similar ...
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1answer
38 views

differences of Aurora Borealis (North) vs. Aurora Australis (South)

I was wondering about the differences between the Northern vs. Southern lights: will one pole collect the positive charges, and the other the negatives? I know that the solar wind is composed mainly ...
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29 views

How does the velocity of a magnet falling through a solenoid affect the induced voltage?

Given Faraday's Law, $\mathcal{E}=-N \frac{\partial \phi}{\partial t}$, we can induce an EMF by dropping a magnet through a coil of wire. How would the velocity of this magnet relate to the induced ...
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38 views

Why does the primary coil get very warm with DC supply but not with ac supply?

It's about an investigation carried out on the transformer effect . The primary coil of 20 turns and the secondary coil of 50 turns is wound around a laminated iron core.
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1answer
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Verify Faraday's law of induction [closed]

I need to design a procedure for an experiment to verify Faraday's law of induction. I'm given: A Helmholtz coil of radius 15 cm Three plastic spheres of radii 1 cm, 1.5 cm, and 2 cm. A spool of ...
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3answers
34 views

How to determine the concentration and sign of the charge carriers in copper

I need to design a procedure for an experiment to determine the concentration and sign of the charge carriers in copper. I'm given: A slab of copper 2.0 mm thick, 1.5 cm wide, and 4 cm long One very ...
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0answers
33 views

Effect of shielding on a miniature Helmholtz coil

So a bit of background... I'm a university graduate student with primarily digital signal processing and embedded experience. However I've managed to get myself involved with a project that requires ...
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1answer
295 views

Is there a colour “magnetic” field?

Does the colour charge of quarks brings a "colour magnetic field" into existence? When the quark is moving you should expect that it results in the same kind of magnetic field as a moving electric ...
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35 views

Amplifying an electromagnet's generated field

Given an electromagnet like this: which is essentially an iron casing with coils inside: Is it right that the centre disc would have one polarity whilst the outer housing another? To boost the ...
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0answers
32 views

What shape does magnetic dust take under the influence of its own magnetic field?

Recently, I came across some very powerful neodymium magnets (the flat cylinder kind), and I accidentally broke one by snapping two of them together quickly. What I noticed is that the two halves don'...
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1answer
25 views

Thermal equilibrium - magnetization [closed]

The electronic ground state of neutral sodium atoms in a magnetic field splits into two no longer degenerate energy states. In the thermal equilibrium the occupation probability of the states is the ...
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0answers
22 views

Magnetic field between 4 wires with the same current

if I have 4 long wires with a current I and all of them have the same distance from each other (looked at from the front you'd have a square) shouldn't the magnetic field vanish in the middle of all 4 ...
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1answer
41 views

Rewriting Maxwell's equation in tensor form [closed]

Suppose $F_{ij}=\epsilon_{ijk}B_k $, how to prove the following: $\partial_iB_i=0$ becomes $\partial_iF_{jk}+\partial_jF_{ki}+\partial_kF_{ij}=0$ $B_iB_i$ becomes $F_{ij}F_{ij}/2$ I can see that ...
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1answer
35 views

Does a degassed magnet weigh less than one that is not?

I learned matter with an electric current weighs more than matter with no current. Does that apply to magnetic material in the same way but with it's magnetic fields instead of electric current? A ...
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1answer
26 views

Can a magnetic field speed molecules up?

I heard somewhere that If you add a magnetic field to atoms in a closed space you would speed them up. Similarly to heating them up. Is this true is so what the atom consists of for this to work?
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2answers
53 views

How can an electron's magnetic moment precess around the direction of an external magnetic field?

I am reading this article: The Nature of the Electron by Don Lincoln in The Physics Teacher, Volume 54 (2016), pg. 203, and I ran across the part where he talks about measuring the magnetic moment of ...
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1answer
26 views

Are the value of the magnetic field of a current carrying coil and the magnetic dipole moments of the involved electrons comparable?

The magentic dipole moment of electrons is a intrinsic property. To get the macroscopic effect of their common magnetic field this moments have to be aligned, like in permanent magnets or in current ...
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1answer
42 views

When and how does magnetism pass through bodies?

I've seen a video by Walter Lewin in which the magnetic pull between two wires is unaffected when an aluminum plate is situated between them. Can you explain what materials let magnetism pass through ...
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0answers
30 views

Solving Bloch equation for MRI

I am trying to write a numerical solver for Bloch equation to track the magnetisation of a spin during the excitation and relaxation processes. The general Bloch equations can be written as: $$ \...
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0answers
12 views

Factors Effecting Neodymium Magnet's Grades and Strength?

Neodymium magnets have different grades in strength. Such as: N38, N45, N52... etc [ Where higher number means greater strength, in MGOe ] Since all magnets are made by saturating them in magnetic ...
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52 views

How to calculate the energy transfer between working coil and working piece and dissipated energy of working piece in induction heating?

For who don't know how does induction heating work, a short description can be found here. However, my question is about physics. Assume I have a coil inductor calculated carefully 50 uH as below: ...
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1answer
28 views

What would happen if a magnet was pushed towards a copper tube in space?

So the question was inspired by one of curious comments on youtube. What exactly would happen if you pushed a strong neodymium magnet towards the copper tube (aiming for the opening in an effort to ...
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0answers
35 views

What is the physical meaning of a magnetic conduction current?

In electrodynamics, it is possible to have an electric conduction current, whereby $J=\sigma_e E$, with $J$ being the current, $\sigma_e$ the electrical conductivity and $E$ the electric field (this ...
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3answers
169 views

Why geologist do not consider molten iron in the magma to be the source of Earth's magnetic field?

This was a question that came in a exam. How come is this possible? Actually, a question on the source of Earth's magnetic field was asked here on physics SE, which matches my opinion. The ...
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1answer
63 views

Is diamagnetism a static or dynamic effect?

When we put a diamagnetic material in the presence of an external magnetic field $\vec B_0$, the magnetic field inside the material decreases to $$\vec B=(1+\chi_m)\vec B_0,$$ where the magnetic ...
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0answers
25 views

The velocity of the charged particle in the magnetic field [duplicate]

Enrico Fermi considered that moving charged particle gains energy in the magnetic field, so its velocity increases. According to the Lorentz Law $\vec F=q\vec v\times\vec B$. Work is $A=\vec F\times\...
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0answers
36 views

Is my definition of a dipole and its dipole moment correct?

Assume that we have a dipole affected only by an applied magnetic field where only 2 possible orientations for its dipole moment are possible: "up" and down". A dipole is simply an object with a ...
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1answer
38 views

spinning compass

There is an area where I live that prevents my compass from giving a solid direction; instead it just spins. Does this mean that this area lacks a magnetic field, or has to many of them for my ...
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0answers
18 views

How can I approximate calculate the magnetic force between electromagnets?

I try to find an approximate amount of force exerted between two electro magnets. The below site could've helped me but the problem is that the below just talks about the number of coil turns and so ...
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1answer
54 views

Magnetic field induce photons?

So silly question, can a oscillating magnetic field excite electrons around atoms such that they produce photons (In other words can an applied magnetic field increase the energy level of electrons ...
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1answer
52 views

Eddy currents in a superconductor

Just had a lesson we just had our teacher introduced the concept of eddy currents, and showed us how a magnet moves slowly through a metal tube due to the opposite generated magnetic field. If you ...
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1answer
26 views

Net magnetic field in a loop

The Ampere's law states that the net magnetic field in a loop is proportional only to the current inside the loop. So if we calculate the net magnetic field in figure 1 and figure 2 we would obtain ...
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0answers
19 views

Magnetic susceptibility anisotropy

I have some problems in understanding magnetic susceptibility anisotropy. I know that magnetic susceptibility can be described via a rank 2 symmetric tensor so the magnetization induced in a sample is ...
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1answer
29 views

Finding the electric field in a bar moving through a magnetic field [closed]

In this diagram: I'm supposed to find the electric field through the bar at equilibrium. I know that at equilibrium, the accumulated positive charge on the bottom of the bar results in a field that ...
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0answers
21 views

Precession or projection?

A spin of 1/2 in a magnetic field is known to rotate around the direction of the field. But then it is also stated that it must be projected spin up or down. Is this simultaneous or happens after ...
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0answers
35 views

RL vs RLC circuit magnetic field

If I want to create an alternating magnetic field using an inductor, what difference would it make to use a series RL or a series RLC circuit ? How will the presence of a capacitor affect the magnetic ...
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1answer
81 views

Magnetic field of a solenoid vs magnetic circuit

The magnetic field in the middle of a solenoid is : $$B = \frac{\mu_0 N I}{L}$$ where L is the length of the solenoid The magnetic field in the air gap of a magnetic circuit with constant cross ...
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2answers
34 views

Direction of magnetic field

How did we know that the direction of magnetic field is from north to south and not the opposite? For example, we may use iron filings, and they will take the shape of the magnetic field, but how we ...
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1answer
56 views

Biot–Savart law for a finite wire or the center of a square coil

I need to find the magnetic field inside the center square of a coil (I think this is the name, I'm translating, but if not, I'm talking about a loop of a wire, just 1 turn) of side $50cm$. So, I ...
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1answer
86 views

What is exact difference between gravitational force and magnetic force? [closed]

I've read that gravitational force is due to mass only and magnetic field is due to moving charged particles. But my question is: what are other difference between them? Can we set up a small ...
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0answers
25 views

Wire with current in magnetic field $\vec{B}$has force $\vec{F_1}$. When rotated, $\vec{F_2}$. Find $B$ [closed]

I have the following question: In a wire with $10cm$ there is a current $4A$ going 'upwards' in the $z$ axis. The force over this field, under a constant magnetic field $\vec{B}$ is $F = -0.2\vec{i} +...
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0answers
37 views

How to calculate maximum magnetic flux density of magnet?

I have some magnets of which I need to calculate the maximum magnetic flux density B. I don't have any dedicated setup to measure the value. Is there any way in which I can measure it by relating it ...
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1answer
15 views

Which way is the magnetic field headed? [closed]

Question Is the magnetic field directed into the page or out of the page? I am using this right hand rule --> RHR So anyhow, my index finger is pointing downwards, and since the magnetic force is ...
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3answers
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Right Hand Rule on the magnetic field not working? [closed]

Background: The magnetic field is going into the page and the velocity of the particle is going towards the right. What is the sign of the particle? I keep getting this wrong. The magnetic field is ...