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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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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57 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
81 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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47 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
57 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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49 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
50 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) $...
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1answer
42 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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277 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
40 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
50 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
133 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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39 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
107 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
34 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
87 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
512 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
25 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
32 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
107 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
31 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
109 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
64 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
85 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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0answers
26 views

Fréedericksz transition question

What is the lowest voltage needed for a Fréedericksz transition to occur?
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2answers
48 views

A Magnetic Path?

I've noticed an amazing phenomenon while playing around with magnets, pulling them apart requires tremendous force(like with neodymium magnets). However, slidning them apart requires a lesser(greatly) ...
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2answers
44 views

Field due to a moving magnet

Say you are in a fixed reference frame. Bob, is in a moving reference frame. Also, Bob has a bar magnet. If Bob were moving toward you with a magnet, would the value of the magnetic field you measure ...
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27 views

What is the general proof that the torque acting on an irregular current carrying loop in an uniform magnetic field is only dependent on area?

How do you prove that the torque acting on an irregular current carrying loop in an uniform magnetic field in the plane of loop = $I \vec{A} \times \vec{B}$ Where, $ \vec{A}$ = Area vector of the ...
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0answers
45 views

Will matter vibrating at THz frequencies emit light?

Much like a magnet creating an alternating current when slid through a solenoid, will matter that vibrates at 500 THz create lightwaves? Here we are talking about taking an object which doesn't glow ...
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46 views

What's the formula to determine how fast a magnet can travel and still hold objects in it's magnetic field?

If an object (an iron ball) is locked (suspended) in the magnetic field being produced by a magnetic bar, what is the maximum velocity at which the bar can be moved before the iron ball is disturbed ...
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1answer
52 views

Auxiliary magnetic field identically zero?

Consider a 3D space that's filled up completely with a material of fixed magnetization $\mathbf{M}$ (i.e. everywhere in space the magnetization points in the same direction and has the same magnitude)....
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1answer
73 views

Can iron core from solenoid be diamagnetic?

So... we were measuring RLC circuit, and while we inserted core into solenoid, the amplitude on osciloscope decreased. It would imply, that the core is diamagnetic. But it is original core from PHYWE ...
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1answer
49 views

Can the use of a magnetic compass be inconsistent with Galileo's Relativity Hypothesis?

I just read Galileo's Relativity Hypothesis from this website: http://physics.ucr.edu/~wudka/Physics7/Notes_www/node47.html It states that - "any two observers moving at constant speed and direction ...
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2answers
33 views

Calculate magnetic field from magnetic force on a charged particle

The magnetic force, charge, and velocity of a particle are given. I am asked to find the magnetic field. $$q = -2 \,\mathrm{\mu C}$$ $$\vec{v} = (-\hat i + 3\hat j) \times 10^6 \mathrm{m/s}$$ $$\vec{...
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2answers
75 views

Magnetic field at the center and ends of a long solenoid [closed]

A long solenoid has current $I$ flowing through it, also denote $N$ as the turns per unit length. Take its axis to be the $z$-axis, by symmetry the only component of the magnetic field inside is $B_z$....
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2answers
289 views

why don't large magents repel themselves

This question may have been asked before so I apologize in advance if it has. I've been playing with some magnetic buckyballs I got recently (highly recommend getting some if you dont have any) and ...
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3answers
194 views

Can pulsating DC current be transformed?

Since pulsating DC current is changing, why doesn't it induce a changing magnetic flux in the transformer core? Is it able to induce a transformed current in the secondary coil?
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Are magnets attracted to mu-metal?

Are magnets attracted to mu-metal? Be aware that when watching videos of mu-metal they may have metals that are attached to the mu-metal and are attacted to magnets. Please don't get them confused.
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3answers
116 views

Why can the divergence of vector potential be anything?

Purcell in his book was deriving the vector potential $\bf A$ using $\text{curl}\;(\text{curl}\; \mathbf A)= \mu_0 \mathbf J\; .$ After some algebra, he came to this: $$-\frac{\partial^2 A_x}{\...
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4answers
172 views

Why does the frequency of a Transformer not change?

I was reading about the transformer, when I came across a note by the author that stated that the Frequency is not changed as the flux linked to the secondary coil in a transformer changes. Is there ...
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14 views

Books about non-uniform magnetisation

I need to study non-uniform magnetisation and the only book where I found this was Berkeley Physics Course Vol.2. Is there other book's options to this issue?
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3answers
155 views

Has this double slit experiment been performed with electrons?

I don't know if we have the technology yet. Double slits, one electron at a time. The moving electron should produce a magnetic field. Can we detect such a weak magnetic field and tell which slit ...
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0answers
75 views

Magnetic hysteresis energy loss derivation

we have that the magnetic energy stored in a field is : $$W_m = \frac{1}{2}\int_v B.H dv$$ From here im unsure how to get to the expression that the power dissapated in a hysteretic cycle is given by ...
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1answer
22 views

how is current measured through ammeter? [duplicate]

If we join a shunt through a galvanometer,it makes an ammeter.but in parallel arrangement voltage is same and only some amount of current is passed and not the total current of circuit.so how does the ...
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1answer
296 views

Is the number of turns in a loop part of the magnetic flux?

In all both my physics textbooks, the number of loops $N$ is left out of the equation for magnetic flux $\phi_B = \int_s \vec B \cdotp\hat n dA$ and only when calculating the Emf induced by an ...
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1answer
15 views

Local nuclear magnetic field compared to macroscopic field

In an NMR experiment, I the local magnetic flux density of an iron sample was found to be roughly 33 T, by checking for a resonance frequency of the magnetic dipoles. How can it be that such a high ...
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0answers
49 views

What kind of cheap, available, magnetic metal could I use for my boardgame? [closed]

My question revolves around my need to snap plaster walls to plaster dungeon floors for a boardgame called Dungeons & Dragons. My intention is to glue and paint over metallic strips under the ...
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2answers
60 views

Is it possible to shield a magnetic field?

Is it actually possible to shield a magnetic field? They teach us at school that magnetic fields are generated by electricity running through the wires (that's how electromagnets work). On the other ...
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35 views

Redirectioning photons through magnetic lenses

What shape magnet/s would I need to create parallel lines from the ends of a rod shaped magnet?or what shape of magnet would create parallel lines? Is this close?
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19 views

Levi-cevita symbol, force on current by magnetic field of other current

I have the expression for F⃗1, the force on I1 due to the magnetic field of the current I2, using the Levi-Cevita symbol. However, one part of this double integral should equal zero mathematically or ...