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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does thickness of a diamagnetic material affect the mag-lev effect?

I built a little mag-lev display, basically a desk ornament, as a fun project/learning experiment. It's a fairly basic setup with a neodymium magnet suspended between two thin sheets of pyrolytic ...
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1answer
33 views

How and why do sunspots occur?

I am studying sunspot behavior, and the causes for the occurrence sunspots occur. I've come across the phrase 'local magnetic fields of the Sun'. I have no idea what that means. Can someone please ...
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1answer
110 views

Ampère's law from Biot-Savart law for linear currents with multivariate calculus

My book, W.E. Gettys's Physics, starts from the Biot-Savart law $d\mathbf{B}=\frac{\mu_0}{4\pi}\frac{Id\boldsymbol{\ell}\times\hat{\mathbf{r}}}{r^2}$, ...
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0answers
23 views

Is it possible to create a magnetic field camera that resolves magnetic fields to their source?

Is is possible to build a camera that is composed of an array of compasses that can resolve its magnetic field readings to sources outside of the sensor similar to the way an optic camera creates ...
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1answer
40 views

emf of a moving wire in a variable magnetic field

Lets, say that Magnetic filed is either (case 1) $B=B_0$ or (case 2) $B=B_0\sin{\frac{\pi x}{L}}$in $z$ direction. We have a wire with a length of $L$ along $y$ axis which is moving in $x$ direction ...
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45 views

Why is one Telsa equal one weber per square meter instead of one weber per cube meter?

Lines of magnetic flux exist in three-dimensions, so how can they be measured per area unit?
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22 views

Modeling the working of a transformer by pushing magnet into a coil

Let me go step-by-step. First I will outline a simple transformer. There are two circuits next to each other (not touching). One is an electromagnet set-up (with AC supply) and the other has a ...
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1answer
32 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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1answer
15 views

Hysteresis curve for ferromagnet different types?

If you type 'hysteresis curve for ferromagnetic' in to google you get several different types. Looking at the once with $B$ against $H$ there are some that appear to go flat at satruation: And ...
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1answer
62 views

Magnetic field felt by an observer “orbiting” a proton

Classically, if one has an electron orbiting a proton, how can the magnetic field felt by an observer with the same instantaneous velocity as the electron be calculated? It seems that I may find the ...
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1answer
220 views

Beyond the gravity of a black hole

http://www.sciencealert.com/the-magnetic-field-just-outside-our-black-hole-has-been-studied-for-the-first-time reported strong magnetic fields escape out of black holes. Does that rule out photons ...
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2answers
50 views

How do virtual photon cloud produce discrete magnetic field lines in bar magnet?

I think magnetic field is the exchange of virtual photon constantly absorbed and emitted by electrons roughly speaking so assume the setup isn't in a complete vacuum and I have a piece of bar magnet ...
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0answers
19 views

Do diamagnetic ferrofluids exist?

I am wondering if there are ferrofluids or 'diafluids' that exist which are repelled by a magnetic field?
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1answer
78 views

Do iron bar become heavier when magnetized?

Say I have a piece of iron bar, would the same iron bar weights more when being magnetized asumming no outside forces like magnetic field etc and the scale is non magnetic, I think you know what I'm ...
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1answer
62 views

How to 'smooth/flatten' the surface of a disturbed liquid

I would like to essentially flatten or smooth the surface of a viscous liquid after dropping an object into it, without actually touching the liquid. For example, if I drop a rock into a tub of oil, I ...
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1answer
54 views

What does radiofrequency really do in NMR & MRI?

In NMR, the protons’ frequencies are affected by the magnet which makes them precess around its magnetic field so now all protons will have different frequencies according to their environment ...
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3answers
127 views

Which elementary particles are behind magnetic field, similar as photons behind radio waves?

I see, there are photons behind radio waves. As Wave–particle duality said: the radio waves are waves and at the same time are fluxes of particles called Photons. I'm wondering, what is behind ...
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0answers
49 views

As the World Turns [closed]

Does the Earth's axis change with the magnetic reversal as it is taking place?
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13 views

How to calculate the maximum spacing between Hemholtz coils

I would like to design a long, uniform magnetic field using Hemholtz coils but am not sure how far I can separate them before the field lines diverge and become two loops that go around each coil ...
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1answer
165 views

Earth Maybe a Compass or Not [closed]

Does the Earth magnetic pole point to something in our solar system or farther? Like the Sun.
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1answer
57 views

Why is the magnetic field of a spherically symmetric current zero?

We now ask about the magnetic field produced by the currents in this situation. Suppose we draw some loop $\Gamma$ on a sphere of radius $r,$ as shown in Fig. 18–1. There is some current through ...
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1answer
37 views

Permanant Magnet Lines & Currents: [duplicate]

A permanent magnet produces lines of magnet flux that we call a "magnetic field". Those lines come from inside the magnet, come out of the N pole, loop outside the magnet, & return back into the ...
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2answers
31 views

Permanent Magnet Lines & Currents:

A permanent magnet produces lines of magnet flux that we call a "magnetic field". Those lines come from inside the magnet, come out of the N pole, loop outside the magnet, & return back into the ...
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1answer
36 views

Magnetic force of a magnetic field around a wire

Suppose we have a magnetic field around a wire because there goes a current through the wire. Suppose there are not any magnets near. Is it ture that there is then also a magnetic force? If so, is ...
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1answer
44 views

Does current in a part of a wire create magnetic field at any other part of the same wire?

Let there be a circular-shaped wire - a ring in which there exists a steady current. It creates magnetic field around the wire. This can be evaluated by Biot-Savart Law. As shown in the fig., ...
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0answers
17 views

Calculating the deflection of an electron in a given magnetic field [closed]

I have been stuck on this question for some time but I am not able to solve it. It is a question from "Concepts of physics" (2nd volume) by H.C. Verma. An electron is projected horizontally with a ...
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0answers
25 views

How to create linear parallel magnetic field lines

I am trying to make ferrofluids create a flat surface between two points. Most of the magnet configurations I have seen have field lines that arc. So I'm asking if there are any circumstances where ...
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1answer
74 views

What is the speed of magnetism?

I'm not a physicist (just have a few basic notions) and this is a question out of curiosity, so as I'll probably word it the simplest I can, please take that into account when answering. tl;dr Let's ...
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0answers
27 views

Ferrofluids and normal-field instability

Could someone explain whether the spikes and uneven surfaces you see in ferrofluids being attracted or repelled away away from (against gravity) the surface of ferrofluids would happen if the fields ...
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2answers
48 views

what happens to a magnetic field when it moves relative to an observer at relativistic velocities?

what happens to a magnetic field when it moves relative to an observer at relativistic velocities? Does it become an electrical field?
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2answers
39 views

Electropermanent Magnet not working?

I have made an electropermanent magnet based on summary provided on this blog. Here are my details - I have used AlNiCo and Neodymium Magnet together in the core with 10mm diameter and 20mm length. ...
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1answer
30 views

How to calculate the magnetic flux through a circular area [closed]

A constant magnetic field passes through a circular area (of a solenoid). I'm trying to calculate the flux using $$\phi_B= \int B dA$$ $B=0.2$ Tesla, Diameter of the solenoid (and therefore circle) ...
3
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1answer
28 views

Why does cutting slots in metal improve magnetic flow?

When machinists mount work pieces for grinding they often use magnetic chucks and fixtures are set on those chucks. The thicker the fixture, the more the magnetism is attenuated. Sometimes that is a ...
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1answer
226 views

Motion in a time-dependent uniform magnetic field

Suppose you have an infinite solenoid generating an uniform magnetic field inside. The field is oriented along the solenoid axis : unit vector $\vec{\bf n}$. The field intensity varies linearly with ...
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1answer
25 views

Torque as if magnetic force were concentred in mean point

From what I see in my textbook and several on line resources (such as this, p. 8-8), I am tempted to think that the magnetic force $I\boldsymbol{\ell}\times\mathbf{B}$ acting on a straight conducting ...
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1answer
33 views

What is the magnetic field at a distance along the axis of a strictly elliptical solenoid? [closed]

And at what rate does it decay as we move perpendicular to the axis?
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1answer
73 views

How force get transmitted when a magnet attracts iron?

According to particle physics , every fundamental force has its force carrier particle. Photon is a force carrier particle of electromagnetic force but how does force gets transmitted when a iron is ...
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0answers
14 views

Does a permeable core increase flux or only concentrate what's already there?

I understand that that introducing a high-permeability core (say iron) into an air-core coil (having some current running through it) increases the flux density $B$ in the core. Does the iron core ...
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4answers
97 views

About the uniqueness of the displacement current

In the Maxwell-Ampère equation, i.e.: \begin{equation} \nabla\times\vec{B} = \mu_0 \vec{J} + \mu_0\epsilon_0 \frac{\partial \vec{E}}{\partial t} \end{equation} the $\vec{J}_d$ term: $$ \vec{J}_d := ...
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0answers
27 views

Strongly Influencing Electric & Magnetic Field Forces:

Why is it easier to block electric field forces than magnetic field forces in close ranges to the source? What is the best way to block, redirect, and minimize the strength of half of the lines of ...
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2answers
67 views

Torque due to magnetic force on a loop

I read that the torque due to the force exerced by a uniform magnetic field $\mathbf{B}$ on a closed conducting rectangular loop is $$\boldsymbol{\tau}=I\mathbf{S}\times \mathbf{B}$$where $\mathbf{S}$ ...
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3answers
208 views

Do moving charges get affected by the magnetic field they create while moving to constitute current? If not, how can self-induction be possible?

Let a bunch of charge move with a constant velocity $\mathbf v\;.$ Since, the charges are moving, they would create magnetic field $\bf B$ as it is current that produces magnetic field. Now, would ...
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1answer
22 views

Magnetic force on a wire: how to calculate it

I read in my book of physics, E.W. Gettys' Physics 2, that the magnetic force acting on an "infinitesimal segment" $d\boldsymbol{\ell}$ (I apologise for such language, often used in elementary physics ...
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1answer
30 views

Shift in pixels between 2 tissues in MRI

I have the following question: given a known chemical shift $\delta$ between 2 tissue proton resonances and a MR image sequence with a total spin-echo sampling time of $t$ ms, what is the spatial ...
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1answer
62 views

Finding the force between parallel currents using the formula of magnetic pressure

Let there be two parallel current-carrying infinitely-long wires separated by $d$ carrying currents $i_1$ & $i_2$ respectively in the same direction. In order to find the force on an ...
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0answers
30 views

Does curvature of space affects magnetic field?

I just want to know can strong gravity such as a black hole bends magnetic field lines?
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2answers
95 views

How can a sheet carrying current get affected by its own magnetic field?

I was reading ' Change in B at a current sheet ' in Electricity & Magnetism by Edward M Purcell. this is the concerned excerpt: Consider a square portion of the sheet, $1~\text{m}$ on a side. ...
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0answers
22 views

How to calculate motor torque & rpm

I watched a DIY video recently about a brushless DC motor. How would one go about calculating the max torque & max rpm (under no-load & a given load conditions) of that motor based on the ...
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2answers
58 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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22 views

Fréedericksz transition question

What is the lowest voltage needed for a Fréedericksz transition to occur?