All Questions
Tagged with electromagnetic-induction magnetic-fields
513
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Length of helix in one time period [closed]
How to find the length of a helix in one time period?
In the case of a particle suspended at the origin and a magnetic field along the $y$ axis we know that the time period will be equal to $2\pi/aB$ ...
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1
answer
34
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Internally, what defines whether a material is magnetically hard or soft?
I know that magnetically hard materials hold magnetic fields (magnetic moment alignment) for longer, while soft metals do not. However, what, internally, causes these properties to arise?
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0
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34
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Confused between induced emfs
We know when flux of B changes an EMF is induced in loop
And also when a rod moves in mag field Potential difference between its ends is also produced.
So is this ques while writing Potential equation
...
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-2
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31
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Self-inductance of $N$ turns coil to current loop [duplicate]
I saw nice problem, that tricked my mind. The system is:
Given that the coil has self-inductance of $L$, with diameter $D$ and $N$ turns. Now we take the coil, and open the turns to form single loop. ...
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2
answers
71
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Magnetic flux and number of turns
The number of windings is not written in the magnetic flux formulas in high school textbooks, but I come across articles saying that the number of windings affects the magnetic flux formulas. Is this ...
0
votes
1
answer
32
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Magnetic energy terms of system of three circuits
Say we've got a system of coplanar circuits like in the picture with same electric current flowing through them
We know that a system of circuits has magnetic energy
$$\mathcal U_{\,\mathrm m}=\dfrac{...
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1
vote
1
answer
37
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How does any changing magnetic field induce voltage?
Hopefully the title puts in well enough;
a charged particle moving in a magnetic field experiences the Lorentz-Force. If this occurs in a wire and part of the circuit is outside the B-Field then a ...
- 347
1
vote
3
answers
78
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Work done in a moving conducting bar and in a Faraday disk
I deeply apologize for my ignorance, but I am asking this since I still can't seem to grasp what my teachers relayed to me a few days ago about two exercises that I solved in an intrinsically wrong ...
1
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0
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33
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What is the reletive permeability of structual steel?
Help, i need to know what the reletive permeability is of a few materials (listed below) but i can not find the data on the internet. Does annybody know the data or where i can find it?
-s235jr
-...
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answers
59
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Emf induction in a conducting coil placed in a variable magnetic field
Consider a conducting coil placed in a variable magnetic field. By the laws of nature, an emf will be induced in the coil. Between which two points is the emf induced in the coil?
If we consider it to ...
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1
answer
51
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Straight wire cutting magnetic flux - Faraday's law
For a straight wire moving perpendicular to a uniform magnetic field in velocity v,
$$ε=\dfrac{\Delta \Phi}{\Delta t}=\dfrac{BLv \Delta t}{\Delta t}$$
So the induced e.m.f in the conductor as it moves ...
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6
votes
3
answers
216
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Ring Magnet with a wire in the middle
I have a very specific question concerning a system with a magnet and a wire.
Consider a ring magnet with a magnetic field directed right through its center. In the center of the magnet is a wire, ...
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39
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What is the induced electric field in a moving conducting material in a magnetic field?
I've been taught that the induced EMF in a conductor is the rate of change of flux in it, but Maxwell's equation
$$
\nabla\times\vec{E} = -\dfrac{\partial\vec{B}}{\partial t},
$$
only states so for ...
2
votes
1
answer
55
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Does making a magnet move require more energy than a non-magnet?
I know that electric fields store energy, with their energy in an infinetesimal volume being proportional to $E^2$ at that point. I also know that a moving magnet creates an electric field (...
- 531
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12
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Self-induction in a permanent magnet
when a permanent magnet is moved in a coil, an emf is induced in the coil. so is an emf also induced in the magnet itself? and if not then why not. and if I replace this permanent magnet with a ...
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49
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What logic is being used in Bleaney & Bleaney to prove the reciprocity theorem for mutual inductance?
I'm currently reading Bleaney & Bleaney 3rd Ed. On pg 136 they discuss the case of 2 coils. Their logic is as follows:
If a second coil is brought near to a coil carrying a current $I_1$, there ...
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Induced current density and magnetic field arising from forced oscillations of particles in a constant magnetic field?
I am being confused by what should be a simple physical scenario. Let's say I have a small, cylindrical region of radius and height are both $a$ filled with a medium of both positive and negative ...
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1
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36
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Induced Electric field due to magnetic field in Faraday experiment
Regarding this experiment where a magnet is moved in and out of a coil -(see the picture)
what i considered to be true is that when there is a changing magnetic flux through the coil(due to changing ...
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6
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4
answers
727
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How do Electric and magnetic fields generate each other (mathematically)?
Regarding electromagnetism, a changing magnetic flux$(\phi_B)$ produces emf by-$$EMF= -\frac{d \phi_B}{dt}\tag1$$
This emf creates a current which again creates a magnetic field given by-(bio-savart ...
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3
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69
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Are there losses in an ideal transformer?
In a circuit with an AV power source $V$ and a zero-resistance ideal coil, the power from the source. $P_{in} = IV$ is equal to the rate of change in the magnetic energy $U_B$ stored in the coil. The ...
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57
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I can’t figure out the magnetic field around a non-straight wire
Say I have a circuit where the wire has a shape defined by some closed
Parametric defined as $(X(t), Y(t), Z(t))$ (it is a loop), how do I calculate the entire magnetic field around the circuit?
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2
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42
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Magnetization current when two magnets are brought together and the Lorentz force law
Suppose we have two ferromagnetic objects constituting two permanent magnets. A classical way to think of the two magnets repelling/attracting each other would be by ascribing bulk and surface ...
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Inducing electric field vs Inducing magnetic field
Is it easier to induce an electric field using a changing magnetic field or the other way around?
The question is from my high school booklet, and I am pretty sure it was to be answered on an ...
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35
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Using the magnetic masses model how do i find the induced magnetic field due to a magnetic point charge?
I am deriving an equation modelling a magnetic guitar pickup and I am stuck.
I am trying to derive based on a paper for guitar pickups and it uses a magnetic masses method to find the magnetic flux at ...
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Superconductor Cube levitating in Vertical magnetic field
Suppose there's a Magnetic field in vertical direction and we hold and release a superconductor cube so experimentally it is seen that the cube floats/hovers in the same orientation as it was released ...
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1
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24
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How different is the induced magnetic field of a coil with a solid rod core and a sheet-wrapped one? (Assuming both use the same material)
I'm doing research for a university project and looking for commercial references for Mu metal, I found out that in my country at P2B (particular to business) level, sheets are significantly easier to ...
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Does the Change in Area Not Affect EMF Calculation in a Time-Varying Magnetic Field?
I had this Question as a Homework :
Given a conducting frame of width $𝐿$. A mobile conductor is mounted on the knitting needle that moves on the closing one at speed $\vec{𝒗} = 𝑣\hat{x}$ while ...
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1
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85
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Lorentz force separation from induction in rotating loop within AC magnetic field
I was wondering , is it possible to create a loop of any kind of geometry that could rotate in a non homogeneous AC magnetic field and have no net induction within the loop but only have current ...
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Is there any way to detect localized magnetic field change in a magnetic material or powdered magnetic material?
Hi I was wondering if there was any way to detect localized magnetic field change within either bulk magnetic material or within like powdered magnetic material. The application we are looking for is ...
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2
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136
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Faraday's law and a moving charge
Suppose we have a moving point charge with respect to some conductor which has a shape of a closed loop (e.g. a loop of wire). From the conductor's point of view the moving charge has a magnetic field ...
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94
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When a magnetic ball passes through a copper pipe vertically
Let's say a magnetic ball passes through a hollow pipe, which is a conductor (copper), vertically. We can observe that its acceleration is decreased when compared to a free gravitational fall.
By ...
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3
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108
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How current is induced when there is a change in external magnetic field?
If still charges in a wire loop do not respond to a(or have their own) magnetic field, then how is current is generated by changing a magnetic field? And why only a changing magnetic field? What ...
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179
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Explaining Faraday's Law With Lorentz Transformations of $E$ and $B$ Fields
I've searched around for this but haven't come across a totally satisfying explanation yet. I'm trying to build a relatively simple model of how the Lorentz Transformations of the $E$ and $B$ fields ...
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2
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87
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How does $ \vec{B}$ change when flux surface $A$ gets smaller?
So I am still a student and I just learned the basics of flux. And my teacher told us that flux ($\phi$) is equal to the magnetic field $B$ $\times$ the area $A$ $\times$ the angle of the area $\cos{\...
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2
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145
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Intuition behind self-inductance
I'm having a little bit of a hard time understanding some concepts to do with self-inductance in class.
I understand mutual inductance. That's when a loop has some time-dependent current going through ...
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1
answer
35
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Getting the force somehow using magneticfield force (tesla)
First off, sorry if not everything makes sense, english isn't my first language so some scientific terms may sound weird if they're in English. For a project we are making a coil gun. So we get a ...
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0
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54
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Static toroidal magnetic field rotating inside toroidal winding
what would happen if I took a toroidal core, generated a static toroidal magnetic field in the core and then rotated the core around it's symmetry axis within a larger stationary toroidal winding ...
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0
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21
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Create desired flux density at a desired distance from an electromagnet of simple shape?
total layman here!
I was reading about an experiment on the effects of low-amplitude ELF AC magnetic fields on an ionic solution. The required field amplitude of 0.04 microteslas was generated by ...
3
votes
3
answers
308
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Motional EMF and Faraday's law in this case
My textbook states that when a straight conductor with a velocity perpendicular to itself and the magnetic field (see image), an emf will be induced between the two ends of a conductor. This means ...
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2
answers
480
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Should a wire loop moving through a constant rectangular magnetic field directed perpendicular to it's motion have zero induced current in the middle?
Suppose we have a loop of copper wire moving perpendicularly through a constant finite rectangular magnetic field directed into the screen .
When the loop enters the field, the induced current would ...
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33
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Does the net induced emf decrease in this case?
In a video from the YouTube channel veritasium about Misconceptions of electricity
It is said that energy is mostly of the electric fields produced by the surface charges and battery , which make them ...
- 441
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1
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Energy transmission from opposite magnetic field vectors. A wire with a current in a homogenous magnetic field
This is my first post and also the first time I've ever tried understanding a physics concept by approaching it with my own math logic so tips on trying to do this more effectively are also welcome
I’...
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1
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254
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What is the difference between the induction of a magnetic field $B$ and the magnetic field strength $H$?
I just started learning about magnetic fields by myself. In my textbook it says that the magnitude or intensity of induction of a magnetic field is equal to the amount of field lines that pass through ...
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63
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Variation of Permeability with DC magnetising Field
For any Powder core, as DC magnetising field increases, the initial permeability decreases known as "permeability roll off".
For example for an MPP core-
For MPP cores the initial ...
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6
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1
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If a loop is not complete, and magnetic field passing through it is changing; will their be emf induced in the loop?
In a setup like the one show in the figure:
Will there be an induced EMF across the loop(given that the field is increasing)?
(my dilemma is : since the loop is not complete, we cannot define the ...
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19
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Effect of projectile movement inside the coil launcher
I'm simulating a simple coil launcher system where there is a round coil , a capacitor and a round projectile which at first is placed at the start of the coil.
so the whole circuit is a simple RLC ...
0
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0
answers
23
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Sources of Eddy current and hysteresis in linear materials
Following is an excerpt about transformer on load from Kothari and Nagrath, Electrical Machines.
The value of exciting current $i_0$ has to be such that the required MMF is established so as to ...
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1
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51
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Faraday's Application on a Magnetic Dipole
Consider a closed loop wire with current flowing through it:
Consider along the wire a battery $V$, a resistance $R$ and a capacitor $C$.
We know the integral form of Faraday's law:
$$\oint\limits_{\...
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votes
3
answers
1k
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Why is there a current in a changing magnetic field?
If there is a circular metal loop and a changing magnetic field perpendicular to the loop, there is an induced electric field that causes the electrons to move and cause a current. But my question is ...
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4
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3k
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Magnetic field changes induced by vibrating electric guitar string
Here is a picture (from a paper by Feinberg and Yang in the Journal of the Acoustical Society of America) of an electric guitar string vibrating (mostly in the $y$ dimension) near a permanent magnet.
...
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