All Questions
79
questions
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3
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80
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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 ...
0
votes
0
answers
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
0
votes
1
answer
37
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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 ...
- 367
6
votes
4
answers
729
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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 ...
- 367
0
votes
2
answers
36
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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 ...
- 15
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0
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27
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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 ...
- 101
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3
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110
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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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1
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181
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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 ...
- 43
1
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0
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57
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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 ...
- 91
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1
answer
24
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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’...
- 5
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 ...
- 421
0
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0
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22
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How does proximity of a grounded conductor effect an electric / inductive field (and practical application)
My apologies - I'm missing a couple years of learning to be able to ask this question well, to know the right terminology.
Suppose a grounded conductor, such as a 12mm copper water pipe.
The grounded ...
0
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1
answer
97
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Conducting rod moving in magnetic field on a railing problem
We have a conducting rod (lenght $l$) moving with constant velocity $v$, on two symmetrical railings, and and everything is conducting. Rod has some resistivity $\rho$, while railings are purely ...
- 2,042
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2
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157
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Is the concept of motional EMF consistent with Faraday's Law?
Consider a circular homogeneous metallic coil sliding on a smooth horizontal surface in a region of uniform magnetic field $B$ which is perpendicular to the face of the coil. By Faraday's law, the net ...
- 341
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1
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47
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Can ionized air be used as a conductive medium for eddy brakes?
Sort of a conceptual engineering question, apologies if I am missing something, my background is in mechanical engr.
Essentially, I was inspired by the classic experiment of dropping a magnet in a ...
0
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2
answers
78
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What type of electric field is created by time varying magnetic field?
Example when an current carrying loop is placed in external magnetic field varying with time some emf is produced in the coil now we know that emf is due to electric field and the loop is experiencing ...
6
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3
answers
1k
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Suspicious EMF equation
Some context: I am trying to get the equation of motion for a dipole magnet falling through copper pipe. To proceed I need to calculate the EMF. We can do this by using Faraday's law,
$$\oint_{\...
0
votes
1
answer
292
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How to identify north pole of a magnet using only a battery, and a copper wire? [closed]
I have a magnet, a copper wire, and a battery. I need to find the north pole, and the south pole of a magnet using only these items. (not a compass).
Here's my attempt: create a circuit, battery is ...
0
votes
1
answer
257
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Is the induced electric field in a current changing solenoid actually that what we call magnetic vector potential field?
Induced electric field $E$ in a changing current (i.e. changing magnetic field $B$) solenoid
image creditis: https://faculty.uml.edu//Andriy_Danylov/Teaching/documents/L18Ch33InducedEcovered.pdf
I was ...
- 4,170
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2
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84
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Is Farady's law valid for conducting loop only? [duplicate]
Is it applicable to a nonconductive loop? What if the loop consists of both non-conducting and conducting paths?
- 480
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1
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233
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Induced voltage from magnetic field
Suppose we have a surface S(x,y) = x^2-2y for 0<x<2,0<y<5 , and a magnetic field (2t,3t+1,t).
To find the total magnetic flux through the surface S we find a normal vector to S n = (-Sx,-...
- 105
1
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3
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512
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Nature of force between two permanent magnets
When we put two permanent magnets close to each other they repel or attract each other and this process increase their kinetic energy. I know that magnetic force can't increase kinetic energy so plz ...
0
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5
answers
512
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Total Energy of an electromagnetic wave
This question may sound stupid. But why when we calculate the total energy density (energy/volume), carried by an electromagnetic wave $u_T$, we add both $u_B$ + $u_E$.
Where $u_B = \frac{B^2}{2\mu_0}...
- 170
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1
answer
262
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Electric field of moving charge
Does the electric field of a moving charge (constant velocity) change with time? Or it remains the same?
I know that changing electric fields produce a magnetic field, but in a straight, current-...
user324098
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2
answers
1k
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Electric field in a vacuum
By changing the magnetic field can we generate electric field in a vacuum ?
By the Faradays law of EMI if the magnetic field associated with a coil changes, current is induced in that coil
So if we ...
user324098
0
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2
answers
151
views
Potential in electric field by magnetic induction
There is a point written in my book (S.L. Arora- Simplified Physics Part-1)-
Electric Potential is meaningful only for electric fields produced by stationary charges. It has no meaning for electric ...
- 13
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votes
2
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591
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Doesn't Faraday's law violate conservation of energy?
Faraday's law says that if we have a changing magnetic field, there will also be an electric field (basically). I already know that both fields have energy. Is this energy given when accelerating the ...
- 857
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62
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Why moving magnet releases more Magnetic radiation as the number of charges near it are increased?
Why does a moving (at constant velocity) magnet release more energy in the form of magnetic fields when the number of charges placed near it are increased?
Say two current carrying coils $C1$ and $C2$ ...
1
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1
answer
286
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Can electromagnetic field(EMF) meter used to detect electromagnetic pulse(EMP)?
In theory,can electromagnetic field(EMF) meter used to detect electromagnetic pulse(EMP)?
- 127
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1
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101
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Do magnetic fields really travel with ${}c$ velocity in space?
I was thinking about a situation: In space there is our setup, a wood piece of mass $m$ and a coil and permanent magnet of mass $m$. The coil is placed a light second far from the magnet. The magnet ...
1
vote
2
answers
199
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Faraday's Law - When do we know when it is a motional EMF or an induced electric field?
So from what I know, Faraday's law states that when there is a change in magnetic flux, an EMF is induced.
This can be explained with motional EMF where when the magnet moves towards the conducting ...
- 67
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1
answer
360
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Does the magnetic force has anything to do with induced EMF in Faraday's law?
So according to faraday's law, when there is a change in magnetic flux, there is an induced EMF.
My understanding:
In the reference frame of the magnet, the charge is moving, hence there is a current. ...
- 67
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2
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583
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Is the induced electric field generated due to the separation of charges in a moving wire in a magnetic field non-conservative?
As the title suggests, whenever there is a moving wire in a magnetic field of constant magnitude, an induced voltage is produced. Now, due to the separation of charges, which is a result of the ...
- 1
3
votes
2
answers
958
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Induced electric field due to a long wire
Given an infinitely long wire, carrying a linearly increasing current, what is the shape and direction of the electric field induced by the magnetic field?
Given increasing magnetic flux in a ...
- 220
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47
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Incongruent expressions for $E$- and $B$-fields based on approach
I am having two issues with Maxwell's equations in the following problem:
A thin conducting disc has radius a thickness b and electrical
resistivity ρ. It is placed in a uniform time-dependent ...
- 545
1
vote
1
answer
57
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Motional EMF inside material with resistance
A square loop is cut out of a thick sheet of material with each side of resistance R. It is then placed
so that the top portion is in a uniform magnetic field B, and is allowed to fall under
gravity.
...
- 105
0
votes
1
answer
61
views
Is there a circulating $E$ field when a single straight wire cuts a magnetic field?
I am a little confused as to the difference between the Lorentz force and Faraday’s induced emf, specifically in the case of a straight wire moving through a uniform B field. I know the answer is that ...
- 103
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votes
1
answer
101
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Uniform electric field formation in motional emf induction
Why is the electric field $E$ across the ends of a conducting rod, when it's moved with a uniform velocity $v$ in a magnetic field $B$, uniform? Wouldn't it vary non-linearly, since there are opposite ...
- 256
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1
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66
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How is a current induced in this translating wire?
I am familiar with the principles of electromagnetic induction, but I am stuck on the scenario below: a long straight wire is translating in a uniform magnetic field. According to my book, this causes ...
- 368
4
votes
6
answers
2k
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Induced electric field inside a perfect conductor
If I have a magnetic field and I place a coil that is a perfect conductor in this field that I'm rotating.
This would mean that there is a change in the flux through the area of the coil which would ...
- 335
1
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1
answer
48
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Induced electric field and electric field due to charges obey superposition?
Say a group of charges and a varying magnetic field exists in some region.
We'll have two electric fields,due to the charges and due to the magnetic induction.
Does the total electric field equal the ...
- 1,270
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3
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280
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Energy density of Induced Electric Field
For electrostatic fields, we write the energy density using $$u = \frac12\epsilon_o E^2$$
is this formula also valid for a non-conservative electric field produced by changing magnetic field?
Or, can ...
0
votes
1
answer
256
views
Faraday's Law (General form) and the Change in flux
For the Introductory E&M class, I am taking this year I was working on some problems involving the general Faraday's Law
$$\oint{E.dS}=-\frac{d\phi_B}{dt}$$
I was confused regarding, How we ...
- 143
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4
answers
139
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How can classical physics explain what happens when a charge fixed by two other charges experiences a magnetic force?
I have invented this little problem to help me understand the magnetic force better.
Imagine 3 positive charges all on a line. The first charge is separated by distance D from the second charge, and ...
0
votes
1
answer
79
views
Does an non-moving electrically conductive metal become magnetic in a full-DC offset AC field?
Let's assume an electrically conductive object made of metal is static and does not move.
Then let's apply an outer electric field. Clearly, a constant DC field would not induce any currents and ...
- 282
1
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0
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106
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Is this analogy of Induced emf correct?
I have searched PSE (and many other sites on internet) for the theoretical reason of induced emf. All I got was that the phenomenon of Induced EMF is experimental fact and can only be mathematically ...
- 876
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940
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Is emf equal to or proportional to the rate of change of magnetic flux?
I'm slightly confused about Faraday's law. Is it directly proportional or is it equal to the rate of change flux? If it is proportional, what's the proportionality constant? It might seem like a ...
- 195
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1
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86
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Does an electric field induced by a time varying magnetic field has an energy associated with it?
Consider a time varying magnetic field. This induces an electric field upto infinity as per Faraday law and other related laws.
Is energy stored in this induced electric field?
If so, what kind of ...
- 1,568
0
votes
2
answers
293
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Induce electric field in an incomplete circular conducting loop
I was solving a numerical example(image1) of 'Griffiths book of electrodynamics'
And in this solution it is given that if there is a changing magnetic field is there there would be induce induce ...
- 178