1
vote
0answers
12 views

Magnetic flux and flow of electrons

What does change in magnetic flux mean? How can you change magnetic flux? How does a change in magnetic flux influence a current of electrons (electricity)?
0
votes
2answers
33 views

Mass of magnet measured by weighing machine [on hold]

I put a magnet on a weighing machine, suppose it shows its mass. Part-1 of the problem: Now, I put another magnet on above this magnet so that it is repelled by the first magnet on the weighing ...
0
votes
0answers
17 views

What is the difference between primary and volume currents in electromagnetism?

What is the basic difference between the two currents and how each is contributing to the magnetic field at source and the surface?
0
votes
1answer
17 views

The difference between EMR and lone Electric and Magnetic fields

I fail to understand the true difference between EMR and electric and magnetic fields. When current flows, there is an electric field due to the electron flow and a magnetic field, however no EMR ...
1
vote
1answer
38 views

What plane is Area in, in this equation?

I have the equation $$F = (NI)^2\mu_0\frac{\text{Area}}{2g^2}$$ Which calculates the force of an electromagnet. I was wondering if anyone knew what plane Area is taken from? I have heard it is the ...
0
votes
1answer
32 views

Force of a solenoid on a ferromagnetic material

As I was trying to find an answer to another problem, I was informed that the equation I was using would not work. The equation I was using was $$F = (NI)^2\mu_0\frac{\text{Area}}{2g^2}$$ If this ...
-1
votes
1answer
33 views

Direction of compass needle nearby an electric wire

Let through a straight wire flow an electric current. Using a compass needle how the needles tip will be directed to the wire? What happens when we switch the current direction and approach the needle ...
1
vote
0answers
48 views

Magnetic Force on a Ferromagenetic Material

I am currently working on a project involving solenoids, and I needed a force(Newtons, not a measure of magnetic field strength) equation. What I came up with after some digging around on the ...
0
votes
1answer
44 views

What physical forces allows for electromagnetic induction

In electromagnetic induction, what force is actually doing the work? what physical force actually drives the electrons around the circuit? Let's say we have a coil and an increasing magnetic field ...
9
votes
4answers
138 views

Is magnetic levitation a good way to vibrationally isolate a speaker from its support?

I recently heard about this company planning to sell a magnetically levitating bluetooth speaker. I understand that the levitation is partly motivated by visual aesthetics, but on the website the ...
1
vote
0answers
20 views

Physical reason for magnetic mirroring?

I understand the mathematical derivation of magnetic mirroring, which usually starts from the conservation of the magnetic dipole moment (e.g. in a plasma). But physically: a mirrored particle is ...
0
votes
2answers
43 views

Magnetic force and relative frame

The magnetic field for to a moving charge depend on its velocity (Biot Savart's law). My question is that is it then not frame dependent? If it is, it means if a man is walking and other is standing ...
0
votes
1answer
24 views

Single Photon emission from positronium in strong magnetic fields; how is momentum conserved?

I recently came across a paper (which I will not describe in detail, however, the authors examine the probability of positronium producing a single photon, while under the influence of a strong ...
1
vote
1answer
38 views

Calculating the magnetic field due to a rotating ring using Biot–Savart law

I wish to calculate the magnetic field due to a charged ring rotating about an axis perpendicular to the plane of the ring and passing through a point on its circumference $(P)$. I arrive at something ...
1
vote
0answers
32 views

Explain the infinitude of magnetic flux about a finite length of wire

Ok so it is clear the flux caused by an inductor is limited. If I integrate about a flat spiral inductor I will find that the flux lines going up are a fixed quantity. Since every flux line going up ...
1
vote
0answers
40 views

Penetration and skin depth in 'metallic' magnetic induction tomography (classical electromagnetism)

Does anyone know how AC magnetic fields behave in 'metallic' magnetic induction tomography (MIT). Do they form a magnetic circuit around a metallic specimen or penetrate through it, or both? This ...
2
votes
1answer
48 views

Magnetic Field in the presence of a conductor

I am studying for my quals and came across an old question that reads like the following: There are two regions in space separated by an infinite conducting plane. Region 1 has a magnetic dipole ...
1
vote
1answer
46 views

Magnet substitution [closed]

I wonder if the two magnet configurations below are equivalent. If they are not - what will be the effects on the flux?
0
votes
1answer
25 views

Magnetic flux of a loop due to another loop

The scenario is the following, I am given 2 loops with the same radius, r, a distance of d, and same current of I. In the left loop the current goes counter clockwise, in the right loop the current is ...
1
vote
0answers
25 views

Magnetic needles in elastic media

I am studying a system with magnetic needles in a elastic media. The (two-dimensional) system is composed of $N$ magnetic needles distributed in an elastic matrix with Young's modulus is $E$. The ...
4
votes
2answers
95 views

Why do ferromagnetic materials channel magnetic field lines?

I have read that the total magnetic field of a ferromagnet, $\vec{B} = \mu_0\vec{H}+\mu_0\vec{M}$ where $\vec{H}$ is an external magnetic field and $\vec{M}$ is the magnetic field of the ferromagnet ...
0
votes
1answer
100 views

Post Problem Analysis - Rod in a cylindrical time varying magnetic field?

A metal rod of length $l$ is placed (as shown in figure) in a cylindrical time varying magnetic field. Find the potential difference across it. My answer: As electric fields as forming circles ...
2
votes
1answer
45 views

Torque on wire summarized with magnetic moment

The magnetic moment of a current-carrying wire loop $L$ is $$ \boldsymbol\mu = \frac I2\oint_L\mathbf{r} \times \mathrm{d}\mathbf{r} $$ so the torque it experiences under a uniform magnetic field ...
2
votes
2answers
80 views

Is it possible to design a large permanent magnet that creates a multi-Tesla field?

Is it ever possible to create a LARGE magnet (in meters wide/long) that could potentially create a powerful magnetic field?
2
votes
2answers
67 views

Can the magnetic fields of EM radiation be harnessed or measured?

We use the electric component of EM radiation to create the EM radiation and to detect it (antennas and Etc.), but does anyone know of a situation where the magnetic component of EM radiation is used? ...
15
votes
2answers
1k views

Why is there no Gravitational Magnetic Field?

We think that the electric field and gravitational field operate similarly with their corresponding charges/masses. With just a difference that the electric field is sometimes attractive and sometimes ...
-1
votes
2answers
50 views

Find electric field given the magnetic field [duplicate]

Given the magnetic field as a vector, how do I find the electric field?
-1
votes
0answers
16 views

Obtain the electric field [duplicate]

Let $V=(xyt^3T)j+(x^4tT)k$. Find the curl of the magnetic field and the electric field. The curl I found to be $-(4x^3t)j+(yt^3)k$ It's sensible to leave out the units T right? How do I find the ...
11
votes
2answers
2k views

Why are magnetic fields so much weaker than electric?

In EM radiation, the magnetic field is $ 3*10^8$ times smaller than the electric field, but is it valid to say it's "weaker". These fields have different units, so I don't think you can compare them, ...
2
votes
3answers
47 views

Magnetic moment - magnetic field relation without free currents

I'm trying to understand magnetostatics in the presense of ferromagnetic material. But I'm ending up in a contradiction: Lets take a piece of iron: Assuming that we don't care about the hysteresis ...
0
votes
2answers
48 views

How to feel or sense magnetic fields from earth?

I know that earth has magnetic fields/forces, but why we don't feel them? So if I hold a magnet and earth's magnetic field is positive and my magnet is from the positive side, then why the magnet does ...
6
votes
1answer
173 views

Reluctance of torus shaped iron core with embedded wire loop

Imagine a circular wire loop (r = 50mm), the wire has an assumed diameter of zero, which is embedded in a torus shaped iron core with a circular cross-section of R = 10mm. A current in that loop ...
2
votes
2answers
104 views

Aharonov-Bohm Effect electricity generation

This question is based on highly intuitive picture of the Aharonov-Bohm effect (perhaps a naive one). From what I have read, the current explanation of the AB effect is that although the electron ...
8
votes
2answers
106 views

Does the geomagnetic field rotate?

The Earth rotates about it's own axis. Do the geomagnetic field lines rotate due to this rotation or not?
0
votes
0answers
60 views

Understanding the mathematical formulation of the Faraday effect

The Faraday Effect is a magneto-optical effect which results in the polarisation of light being rotated I would really want to understand the theory of this, but I only have a basic EM knowledge, ...
0
votes
2answers
95 views

Does a permanent magnet loose its magnetism?

The question is slightly deceiving however still simple for those academics therefore, here I present my question: If I take a para-magnetic material and put it very close to a homogeneous magnetic ...
0
votes
0answers
20 views

Drag on a conductor moving in a uniform magnetic field

Given a conductor moving through a perfectly uniform magnetic field, what is the drag force experienced by the conductor (due to induced eddy currents, or any other magnetic interactions I may have ...
0
votes
0answers
32 views

Finite rod aligned with a time varying magnetic field

A finite length rod is aligned parallel with a magnetic field that has a changing magnitude (let's say a sinusoidal change), given the conductivity and permeability of the rod and assume a large ...
0
votes
2answers
69 views

Curious about this perpetuum concept

I know it's not possible to build a perpetual motion machine, but I still got this concept running in my mind. If you take a (longer)copper coil, and insert an axis through it(right-angled) with a ...
2
votes
1answer
86 views

Why is an electric and magnetic field present in all universe?

the Earth has its fields due to the motion of molten metals in the core but how does this whole universe has its fields without any discontinuity? And we can say for sure that fields are present in ...
5
votes
1answer
102 views

Calculate electric field induced by a changing magnetic field

I want to plot the electric field (as a vector field plot) which is induced by a changing magnetic field for some simple cases. Suppose for example that the magnetic field changes linearly (or ...
21
votes
4answers
2k views

Why do we deal only with large scale magnetic fields in astrophysics, and not electric fields?

In astrophysics there is a lot going on about strong, large scale magnetic fields: in stars (prominences), magnetic dynamos, compact accretors collimating jets, etc. There's even a special ...
3
votes
2answers
111 views

How does a magnetic field cause objects to move?

Let me start off by saying that I never got a degree in any field but I do read and study physics (both classical and quantum); although I personally can't solve quantum physics equations I do have a ...
0
votes
1answer
23 views

Determine stationary angular velocity of wheel with circuit in magnetic field

I have a wheel (free to spin around the $z-$axis) with four spokes that is connected by sliding contacts to a circuit with $U_0 = 0,72V$. Also, there is a B-Field parallel to the $z-$axis For the ...
0
votes
2answers
41 views

Time Varying Magnetic Field

What is said time varying magnetic field? I have heard a lot about it and the Internet is not willing to give me any answers. I assume time varying is a qualification, I was reading around here and ...
1
vote
1answer
70 views

Ion Optics: Electric and Magnetic field. A comparison with Light Optics

When we compare ion optics with light optics, normally we consider electric field. For example Snell's law. $n_1\sin\theta_1$=$n_2\sin\theta_2$. When an electron move from one electric potential to ...
0
votes
1answer
34 views

Is the field generated by an electromagnet always proportional to its current?

Imagine that I use a long wire to create an electromagnet. Let's also assume that the current flowing along the wire is constant, and that the wire is winded on the vacuumm. Is the magnetic field ...
0
votes
1answer
70 views

How do you levitate a foam rock? ('Endless Second' artwork)

I saw this in an art museum: How is this possible? The materials used to make this were foam, wood, stone dust, paint, electromagnets, and metal. I would like to know how this was make and how I ...
2
votes
1answer
81 views

What is equation to find force of magnetic attraction

I was wondering as a student, when I was playing with magnets I thought like Gravitational force equation of Newton's Gravitation Theory, can we also calculate force of an magnetic attraction on an ...
0
votes
0answers
21 views

Torque per unit length on infinite rotating charged cylinder

For homework I have the following question, but I am stuck on finding the torque on the cylinder. An infinite cylinder of radius $R$ carries a uniform surface charge $\sigma$. We start rotating the ...