All Questions
Tagged with electromagnetic-induction magnetic-fields
513
questions
85
votes
4
answers
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If you are vacuuming your carpet and you wrap the cord around your body do you become a magnet?
If you wrap an active electric cord around your body, do you become an electromagnet?
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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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3
answers
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Simple explanation to the induction from the slowly changing $\vec B$ of a solenoid in the region of $0$ magnetic field
I would like to get some elementary intuition into the problem a solenoid fed with a time-dependent current, and the resulting current that such the solenoid field would induce in a loop completely ...
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answers
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I don't understand Ampere's circuital law
Since, magnetic field is a vector quantity, two (or more) magnetic fields (when in close proximity) should influence their fields, according to the laws of vector.
And by that logic, Ampere's ...
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How are the Lorentz force, Maxwell's third law and Faraday's law of induction clasically related?
Faraday's law of induction can be used in any situation where the magnetic flux is changing through a closed conducting loop. While giving the correct answer, it seems to me that for the following ...
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9
votes
6
answers
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Why does a changing magnetic field produce a current?
A changing magnetic field induces a current in a conductor. For example, if we move a bar magnet near a conductor loop, a current gets induced in it.
Faraday's law states that
The E.M.F. $\...
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3
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Can current be induced in a superconductor?
Moving a magnet close to a conductor induces a current. If it consists of a superconducting material with resistance $R=0$, then my textbook says:
Then the induced current will continue to flow ...
- 51.5k
8
votes
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Non-conservative electric fields due to changing magnetic flux?
What I read in several places, tells me that, the fact Coulomb's Law follows inverse-square law and gives a force which is radial, implies that a static electric field must be conservative.(In short, ...
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1
answer
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Why doe we not get a shock on induction cooker?
In induction cooking, eddy currents in cook-pot cause heat to be produced. But why do we not get a shock?
Also, why is it that current is converted to heat while it has a good conductor(say, steel) ...
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8
votes
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answers
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How does an inductor store magnetic energy?
I am trying to figure out what the potential energy of an inductor with a current really means. In a capacitor, the energy stored works like this: if you let the plates attract each other, before ...
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How to generate electric current without a permanent magnet?
The question is pretty simple:
Can we build a device that coverts mechanical work in electric current1 without employing a permanent magnet and without access to any external source of current?
The ...
- 4,577
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2
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Transformer and magnetic field/flux through the iron core?
I am familiar with how a transformer works.
This is the diagram that I found on the wikipedia page:
The current through the red solenoid varies with time, which creates a time-dependent magnetic ...
- 24.9k
7
votes
2
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What is the meaning of Potential Difference in presence of Non-Conservative Induced Electric Field?
Case 1
This is a very commonly discussed case in Electromagnetic Induction. In the case above, we need to find out the potential difference across the rod CD, in the presence of time-varying ...
- 2,517
7
votes
1
answer
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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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4
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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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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_{\...
6
votes
1
answer
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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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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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Direction of Hall current
A Hall current arises when electric currents transverse to a magnetic field exist. In this figure (found online), the Faraday current appears to be going upwards due to a magnetic field pointing into ...
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3
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How to find the direction of an eddy current?
Suppose there is a magnetic field going from left to right. Suppose a thin sheet of metal conductor (e.g. a 1m*1m square) is dropped through the magnetic field such that the plane of the conductor is ...
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5
votes
2
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How does electromagnetic induction work on an atomic level?
So far I have come to know that changing magnetic field (or flux) creates current. This is also known as Faraday's law of electromagnetic induction. The direction of the current is opposite to the ...
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Fundamental, intuitive interpretation of the magnetic field $\vec{H}$
In many electrodynamics/magnetism textbooks it is stated that the magnetic induction $\vec{B}$ is related to the magnetic field $\vec{H}$ via $\vec{B}=\mu_0(\vec{H}+\vec{M})$. It is then argued that $\...
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Does changing the electric / magnetic field cause self-reinforcing induction of the other?
I understand that changing electric field produces magnetic field and changing magnetic field produces electric field.
Are these produced magnetic and electric field produced due to one defined to be ...
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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 ...
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3
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225
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Which is more correct - a changing $B$ field induces a current or an electric field?
I am in an introduction to Electricity and Magnetism class and we are using Griffiths. In example 7.8 on page 318, his solution says that the "changing magnetic field induces an electric field". But I ...
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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 $\...
user36790
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How to calculate the energy transfer between working coil and working piece and dissipated energy of working piece in induction heating?
For who don't know how does induction heating work, a short description can be found here.
However, my question is about physics. Assume I have a coil inductor calculated carefully 50 uH as below:
...
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4
answers
611
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Induction cooker + superconductive pot [closed]
What will happen if I put a super-conductive object on an induction cooker, and turn the cooker on?
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2
answers
418
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Why would a moving infinite region of magnetic field exert an electric force?
I'm confused about the Lorentz force in relation to the frame of reference. There are many questions about that here, but I still don't get it. I've tried to break it down to the most basic example.
...
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360
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How does the Poynting vector know who is the primary and who is the secondary of a transformer?
I've read in several places that the Poynting vector is directed from the primary to the secondary of a transformer (we assume here that the primary is the winding that provide the AC energy, while ...
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6
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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 ...
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answer
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Is there is any way to prove the Faraday's law of induction?
I want to know if there is any way to prove the Faraday's law or is it just an experimental observed phenomena?
More specifically, is there any reason why the proportionality constant is 1? How did ...
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2
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Why does induced current depend on the area of a loop of wire?
My year 12 physics textbook teaches the concept of electromagnetic induction in a rather unintuitive way. Perhaps it is not being thorough. Perhaps I am not being thorough in reading it. Here is my ...
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Cause of electromagnetic induction?
The rate of change of magnetic flux through a surface (open) is related with the line integral over the closed loop binding the selected surface by one of the Maxwell's equation. But that means even ...
- 3,148
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votes
3
answers
298
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Voltage across rod in time varying magnetic field
If a slim conductor of some length $l$ and diameter $d\ll l$ is placed in a magnetic field $B$, and the field is changed by $\frac {dB}{dt}$, what (if any) is the voltage $V$ induced across the ends ...
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Use of tungsten as an insulator in an induction heater
One problem in induction heating is that energy is lost because the object being heated radiates energy, that energy then heats the coils (which are water cooled) and the coils suck away the energy.
...
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Why is there no induced electric field in the experiment (Faraday's Law)
Below are three circuit diagrams for each of Faraday's experiments that allowed Faraday to come up with Faraday's Law. In Griffiths' Introduction to Electrodynamics Griffiths states (on page 302 of ...
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Induced magnetic field produces electric field and vice versa forever!
So here are the two of Maxwell's laws that I am interested in:
So we have the simple circuit (from google):
So, before the system goes into steady-state we know that charge slowly accumulates on the ...
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EMF induced in a loop around a solenoid - Faraday's law
Since the magnetic field outside the solenoid is negligible, it is impossible to detect current in the solenoid from outside.
Suppose I put a conducting loop of large radius, say, $10^9 $ km around ...
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Lighting an Electric Bulb with Earth's Magnetic Field
Yesterday, I was solving some problems of Electromagnetic Induction. Suddenly a thought struck my mind.
Earth has its own magnetic Field.If an aircraft of metallic body is flying in the air then ...
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How does Newton's third law apply to magnetism?
As a magnet passes through a solenoid, currents are induced in the wire with an angular momentum. Since the induced magnetic solenoid repels the magnet linearly, it cannot allow for the conservation ...
user86425
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2
answers
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Why in electrostatics is $dV=-E.dr$ but in electromagnetic induction, $EMF=+E.dS$?
In electrostatics we learned that $$dV=-E.dr$$.
I understood the derivation which was used to derive this.
Now when I have come to Electromagnetic Induction,I see that when there is a time varying ...
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Where is the energy stored in an inductor?
In an inductor,
Most text books say that the $(1/2)Li^2$ is stored in the magnetic field.
But is there another way to explain this?
In a capacitor I understand that all the energy that the battery ...
- 43
4
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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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3
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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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3
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311
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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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EMF induced due to moving rod in magnetic field
When a conducting rod moves in a uniform magnetic field as shown.
By Lorentz force it is easy to explain that EMF induced is BvL and upper end is positive and lower end is negative.
But in books, ...
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