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 ...

learn more… | top users | synonyms

3
votes
2answers
223 views

Why bar magnet can produce magnetic field?

Say I wrapped a piece of wire around an iron bar in a closed circuit connected to a DC power supply, the electrons starts flowing and moving charge produce magnetic field. Yet a bar magnet can produce ...
1
vote
0answers
31 views

How does the magnetic current in a MRI machine flow? [closed]

For a project, I was researching about the MRI machine, and I need to find how the electric current in a MRI machine flows.(like which direction, what shape, and how) I have tried google and wiki, but ...
1
vote
0answers
24 views

Do you know if you have zerovalent iron nanoparticles in liquid how to measure minimal magnetic force required for separation of these nanoparticles?

I think of measuring mag susceptibility from VSM data (magnetization divided by the applied field) but I am not sure if this would be enough. Maybe if I employ SQUID measurements, but in that case I ...
1
vote
0answers
27 views

Can I emit light from an inductor? [duplicate]

As I understand it, inductors create a magnetic field when current flows through them, and light is an electromagnetic radiation. So, is it possible for an inductor to generate magnetic waves of the ...
3
votes
1answer
48 views

Conservation of Angular Momentum in Einstein - de Haas effect

I am not really sure why the law of conservation of angular momentum should hold true in the Einstein - de Haas effect. Consider the following excerpt about the phenomenon (taken from Magnetism in ...
1
vote
0answers
22 views

The frequency induced by the alternating current

Let set up the experiment as followed. A string is stretched at two ends. Two magnet poles N and S are placed under and above the string. Now we let an alternating current go through the string with ...
0
votes
0answers
47 views

Magnetic field of a permanent magnet - numerical calculation

I'd like to understand methods for calculating the magnetic field generated by a magnetized piece of material, e.g. a permanent magnet. I was wondering about the approach described here as it seems ...
2
votes
0answers
52 views

Electric field due to a current carrying loop

I want to know how I can calculate the radiated electric field in the far zone of the loop. Knowing that the loop is in center at the origin of a x-y plane Knowing that the loop as a time-harmonic ...
1
vote
1answer
52 views

Can a magnetic field weaken aluminum?

I'm wondering if there is any reason to suspect that applying a magnetic field to a piece of solid aluminum would weaken it structurally in any way. The application is that I would like to put a stir ...
1
vote
1answer
45 views

Difference between flux of wire loop and wire in a uniform magnetic field

How come when a wire loop sweeps out an area in a uniform magnetic field and moves with constant velocity there is no induced current because there is no change in flux. However, when a straight wire ...
1
vote
1answer
155 views

What happens if a current flows through a wire wrapped around a magnetised material?

A cylinder of radius $a$ has a uniform magnetisation along its axis, which results in zero bound volume current density and a bound surface current density $M\hat{\phi}$. A coil with $N$ turns and ...
1
vote
1answer
47 views

How does this approximation of the $B$-field of a charged rotating disk for $z\gg R$ make sense?

Consider a disk of radius $R$ rotating with angular velocity $\omega$ and with a surface charge density $\sigma$. I have shown that the magnetic field as a function of the distance along its axis (z) ...
6
votes
1answer
399 views

Biot-Savart law from Ampère's with multivariate calculus

Let us assume the validity of Ampère's circuital law $$\oint_{\gamma}\mathbf{B}\cdot d\mathbf{x}=\mu_0 I_{\text{linked}}$$where $\mathbf{B}$ is the magnetic field, $\gamma$ a closed path linking the ...
1
vote
1answer
22 views

A doubt on Magnetic domains and electron orbits

If electrons spin not in 2d orbits but 3d orbitals, how is it that in the magnetic domain explanation, we say that electron's motion around the nucleus is like a current loop and hence we get the ...
2
votes
0answers
100 views

What is the maximum magnetic field that a human body can withstand? [closed]

Are there limits to the exposure of human bodies to magnetic fields? What happens if we cross that limit? How to create such magnetic fields? Has this been tried out?
0
votes
0answers
20 views

Earth's magnetic field

New researchs found that very high pressure on certain materials may reduce the degree of temperature required to change to superconductor. So is it possible that the high pressure in earth core ...
0
votes
0answers
18 views

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 ...
0
votes
1answer
64 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 ...
2
votes
1answer
154 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 $d\mathbf{B}=\frac{\mu_0}{4\pi}\frac{Id\boldsymbol{\ell}\times\hat{\mathbf{r}}}{r^2}$, ...
0
votes
0answers
33 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 ...
0
votes
1answer
65 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 ...
0
votes
0answers
51 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?
0
votes
0answers
26 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 ...
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 ...
1
vote
1answer
25 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 ...
0
votes
1answer
77 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 ...
2
votes
1answer
321 views

Do magnetic fields exist 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 ...
0
votes
2answers
59 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 ...
1
vote
0answers
22 views

Do diamagnetic ferrofluids exist?

I am wondering if there are ferrofluids or 'diafluids' that exist which are repelled by a magnetic field?
3
votes
1answer
98 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 ...
0
votes
1answer
67 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 ...
1
vote
1answer
67 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 ...
3
votes
3answers
140 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 ...
1
vote
0answers
51 views

As the World Turns [closed]

Does the Earth's axis change with the magnetic reversal as it is taking place?
0
votes
0answers
28 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 ...
0
votes
1answer
206 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.
4
votes
1answer
116 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 ...
1
vote
1answer
40 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 ...
1
vote
2answers
71 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 ...
0
votes
1answer
67 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 ...
0
votes
1answer
66 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., ...
1
vote
0answers
20 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 ...
1
vote
0answers
41 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 ...
0
votes
1answer
79 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 ...
2
votes
0answers
38 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 ...
3
votes
2answers
55 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?
1
vote
2answers
43 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. ...
0
votes
1answer
45 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
votes
1answer
38 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 ...
7
votes
1answer
268 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 ...