Magnetic Definition and 1000 Threads

Suppose I had an electromagnet that would instantly go to full power when turned on (impossible) and at one light second away a detector capable of detecting the electromagnet. When I turn the electromagnet on how long does it take for the field to reach the detector?

Does the Earth have a charge? so magnetic field? Is there a function to its distribution on the Earth surface? If there's a free charge on the air will it effect by it?

Hello Friends, I have been wondering, is it possible to construct a motor, and attach a coil to it, such that with the motion due to the rotation of the motor, it generates a excess of energy that can be used to power the motor in turn, basically, could i use the excess to charge a battery that...

Homework Statement An electron is at rest in an oscillating magnetic field $$ \mathbf B = B_0 cos\left( ωt \right) \hat k $$ where ##B_0## and ##ω## are constants. What is the minimum field (##B_0##) required to force a complete flip in ##S_x##? Homework Equations $$H=- γ \mathbf B \cdot...

Hi there, we are developing a small consumer electronics product consisting of a small 4-layer PCB along with a few PDM microphones and BLE chip/ and antenna, as well as a LiPo battery. We are locating a small but pretty strong magnet next to these components in the enclosure. It is an N52...

I know that in a Fermi gas, the two common responses to a lo field are Pauli par. and Landau dia. and the last becomes the H-VA effect My question is, it is the same treatment in degenerated Fermi Gas?

Hi! I'm new here. I took physics back when we calculated pterodactyl drag and I remember what an integral looks like but that's about it. I hope I chose the right prefix. What I'd like to do is find the dimensions of N48 neodymium cylinder magnets that would produce a minimum field strength...

To test an Experimental Model , my advisor said to make this investigation; I have a Reservoir of parrafin, Capacity is 50 liters, Around this Reservoir there is a Helical copper Pipe, I have to magnetize the Reservoir by using Helical coil . Many thanks For your assistance

The videos from Veritasium explaining permanent static magnets and electromagnets were quite good I thought… But they have me a little confused with regard to the origins of magnetic fields generated by an electric current as opposed to a permanent static magnet from say iron. 1. An...

Homework Statement Imagine an infinite straight wire pointing at you (thus, the magnetic field curls counterclockwise from your perspective). Such a magnetic field equals to: $$B = \frac{\mu I}{2 \pi s} \hat{\phi}$$ I want to calculate the line integral of ##B## around the circular path of...

Homework Statement A proton moves through a uniform magnetic field given by B=(13.7i−22.9j+23.5k) mT. at time t1 v=(vxi +vyj+1.68k)km/s and the magnetic force is given by F= (4.22e-17i + 2.52e-17j). What are vx and vy Homework Equations F=q(v x B) The Attempt at a Solution First I converted...

Hello I am bemused by a sign convention for Holes, My questions are as follow: For an electron inside the 2D Circular Quantum Well. We can write our Hamiltonian as H = 1/2m * ( p - q A)^2 + 1/2 m w^2 r^2 (Should we use minus in the momentum term? I think for Holes, it is) If we expand this...

I know the magnetic flux inside a hollow conductor is zero. Is this also true if the observer is inside the conductor and the conductor is rotating in relation to the observer so that the electrons are traveling in spirals around the hollow center?

Quick question from an amateur: Assume you have a tidally locked rocky planet around a red dwarf star. I've heard that a magnetic field is or can be dependent upon the rotation of a planet (I've read that the lack of rotation of Venus was a possible reason for the weak magnetic field among...

Homework Statement A superconducting spherical shell of radius R is placed in a uniform magnetic field ##\vec{B_0}## 1)Find the magnetic field everywhere outside the shell 2)the sutface current density Homework Equations Inside the shell the net magnetic field is 0, and at the surface also...

Hi! I had this problem for homework (Mastering Physics), and I'm not sure what I'm doing incorrectly. Is there something fundamental that I'm misunderstanding? Each time I do this, I get 0.717136.. T as my solution 1. Homework Statement I = 12.6 A w = 0.0142 m t = 0.00122 m E_H = 1.82 *...

I am currently working in astromagnetism. My question is, somebody knows if a fermi gas (degenerate electrons) can increase or decrease de total magnetic field due to an influence of an external magnetic field and if somebody have information about that. I know that an external magnetic field...

We all know a moving charge generates a magnetic field. A moving charge also generates a displacement current ∂E/∂t. Is the magnetic field generated entirely due to the presence of the displacement current, or is there an independent, separate effect which contributes to the magnetic field?

Homework Statement There is a square loop with mass of 4.0 kg and side length 4.5 m that is tilted upwards from the ground at a 25 degree angle with one side resting on the surface. The loop is a conductor that has 25 A of current going through it. The question asks to find the strength a...

For light it is said it has no volume and also it it waves of electric and magnetic field. But for electric and magnetic field you need space? So can they both be at the same time?

hello, i have a doubt i bought some small neodimium magnets 8x3mm and now i would like to try some experiments with them i have a doubt: if i rotate one of these magnet around one of its parallel axis, very fast , near 1000000 rpm, what happens to the magnetic field produced by the magnet? if...

When the two current carrying wires (with identical current directions) attract each other, it seems that the magnetic field of wires do work while we know that magnetic force is perpendicular to the velocity of charge. I would like to know whether the the two wires get closer or not? What about...

Can someone provide me with some original experiments conducted which verified the Lorentz magnetic force : F = q(v X B). Google does not give me any links except to explanations of the Lorentz force law.

Is there a prediction/paper/etc. about the mechanical loads that will be reacted onto ITER's magnetic coils? The reason I ask is a simple calculation. My understanding of the numerical figures on ITER are that it is intended to contain; density ~10^20 temperature ~20keV I think that means a...

Assume such a situation, if I have a wire and some part of that wire passes through a hole in the core of an inductor or transformer or any other high magnetic field environment , are there ways to shield the wire, the part that intersects with the B field in order to prevent the field from...

Homework Statement Suppose we have an isolated, long, narrow straight wire with low electrical resistivity. A constant current ##I## is sent through this wire. We know that if an electron is sent on a path which is perpendicular to the wire, towards it, with an initial speed ##v_0##, and the...

A uniform beam of positively charged particles is moving with a constant velocity parallel to another beam of negatively charged particles moving with the same velocity but in opposite direction separated by a distance d. Then, how should be the variation of magnetic field B along a...

So I just learned that in general relativity Magnatic and Electric fields are dependent on the observer. What are some consequences as a result?

The Earth’s magnetic field is slowly moving with respect to the Earth’s surface and to the Sun’s incoming radiation and solar wind direction. Does the tilting/moving of Earth’s magnetic field axis to the incoming solar wind direction change the protection on different points of the Earth’s...

Hi. This picture shows an iron ring shielding a static magnetic field: Does this really work, and why? I know that a conductor can shield an electric field (Faraday cage) and a changing magnetic field (Lenz's law), but why would it shield a static field? Especially since iron is a ferromagnet.

How can we calculate the magnetic field of moving charge by the Maxwell equation ##\nabla \times H=J+\frac {\partial D} {\partial t}##? I mean which term, ##J## or ##\frac {\partial D} {\partial t}##, should be taken into account in calculations? The first, second, or both? Can we deal with the...

This is about the history of electromagnetism. I already know about the convention that defined which electric charge is the "positive" one, which ended up making the electron a negative particle. But what about the "positive" direction of the magnetic field? Does anybody here know how it was...

Just interested to know what the flux saturation of gadolinium is, and what is its Curie temperature? I can't find any data on it at all. thanks.

1. The question... "Blood is a conducting fluid. When flowing through an artery of diameter 10mm which is subject to a constant magnetic field of strength 60mT, an e.m.f. of 0.3mV appears across the width of the artery. Calculate the speed of the blood" 3. The solution... The solution given...

I have a question why a magnet's magnetic field or a coil's magnetic field will not oppose the Earth's magnetic field? Is it because the Earth's field is not strong enough or the magnet/coil doesn't cover enough square area? What formula's would I use to figure out what strength or area I...

So, I have had a bit of a look around and can't come up with a concrete answer, so I thought I'd post my curiosity on here! What is the direction that a compass points in 3 dimensional space, and how is this affected by proximity to North? to clarify what I mean: We all know that compasses...

In the attached picture, the outer wire is carrying a current I(t), and it's asked to find the induced EMF in the inner loop. Now I have indeed calculated the B-field along the z-axis due to the outer loop. My lecturer then puts z=0 into that expression and then multiplied it with the area of...

As shown in the figure, in the Meisner effect, the magnetic field of the magnet bypasses the superconductor. My question is, does the magnetic B field belonging to the magnet increase at the arrow indicating position? Or is there no change in the intensity of the magnetic field that belongs to...

Dear all, I cannot figure out my mistake with this thought experiment: Consider a ferromagnetic material (e.g.iron) in a magnetic field - or just any iron anywhere, since the range of magnetic fields is infinite. Between the ferromagnetic material and (permanent) magnets potential energy is...

Homework Statement There's a very long cylinder with radius ##R## and magnetic permeability ##\mu##. The cylinder is placed in uniform magnetic field ##B_{0}## pointed perpendicularly to the axis of cylinder. Find magnetic field for ##r < R##. Assume there's a vacuum outside the cylinder...

Homework Statement A 40 cm rod is rotated about its centre inside a region of uniform magnetic field of 6.4 T. Given that the speed of rotation is 15 rad/s, find potential difference between the centre and either end of the rod Homework Equations emf = - ΔΦ / Δt ω = 2π / T The Attempt at a...

Hello there! I'm trying to check the first order (1 loop) correction to the electron magnetic moment. I'm following Schwartz and Peskin, but both of them have a point where they hide the calculations, and I'm not sure if my calculations are correct. The point is exactly this: I don't know...

I have a basic question about magnetic fields, but the answer will help me better understand quantum collapse issues. If the current in a wire is instantaneously shut off, what happens to the magnetic field that was present when the current was flowing? To be more specific: Wire...

Homework Statement A particle of mass M, with charge Q is left at the point A. After reaching point P the particle is at the effect of a constant and uniform magnetic field of intensity B reaching point Q. Find H. Homework Equations P=mg Fm=qvB Ke=(mv^2)/2 U=mgH The Attempt at a Solution...

I’m looking for a device to produce electromagnetic fields and how can u control the frequency emitted looking to build or purchase looking to experiment any information either reply publicly or inbox me

It has recently sped up to 30 miles per year, prompting a navigational update mostly for the North Pacific and Arctic regions. https://www.japantimes.co.jp/news/2019/01/12/world/science-health-world/north-magnetic-poles-movement-forces-unprecedented-navigation-fix/

Particles follows accordingly the general equation: $$ m*\overrightarrow{a}=q*\overrightarrow{E}+q*\overrightarrow{v}\wedge \overrightarrow{B} $$ But in the case of two coupled coils the time varying current at primary coil (and its magnetic field variation) creates corresponding varying...

A bar magnet will have a definite magnetic dipole moment, irrespective of the presence of an external field. Why is the moment, then, always defined in relation to the torque it would feel in an external field? Is there any other definition for the same?

Yesterday as I was hiking with my friend, I found a weird rock: My guess is that it is magnetite, since the mountain I found it has the biggest magnetite deposit in Taiwan.But I am not sure.It sticks to neoindium magnets really well. Close up: Is it something else,or it is magnetite as I thought?

The problem: a coil of radius r, length l and N turns, rotating with constant angular velocity ω around an axis perpendicular to its simmetric axis and passing for the center of the coil. The coils is submersed in a static magnetic field, intensity B0, perpendicular to the axis of rotation of...