Questions tagged [electromagnetic-induction]
This tag is for questions regarding to electromagnetic induction, a process in which a conductor is put in a particular position and magnetic field keeps varying or magnetic field is stationary and a conductor is moving. Electromagnetic Induction was first discovered way back in the 1830’s by Michael Faraday.
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Solar powered homopolar motor does not rotate
After experimenting with a battery powered homopolar motor, I thought it would be interesting to make a solar powered version. I 3d printed a frame, painted conductive ink on one side and glued ...
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What is the flux linkage or inductance or induced voltage per unit length of the hollow tube conductor surrounding the inner conductor?
What is the flux linkage or inductance or induced voltage per unit length of the hollow tube conductor surrounding the inner conductor in some section due to the current in the inner thin conductor?
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If I spin a magnet in a coil which has a length parallel to the magnet’s spin axis, is a magnetic field generated along the length of the coil?
This I feel is a bit of a complicated question, so I’ll quickly try to paint as clear a picture as I possibly can:
The magnet is spinning on an axis perpendicular to its poloidal axis (the line which ...
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Doubt in the mode of action of inductor in the RL circuit
I feel that my initial question was slightly incoherent and not precise. So instead of making addendum to the question which is making it lengthier, I am editing it completely. So, sorry about that.
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How does an inductor not having any current through it resist change in current? [closed]
when a steady current is set up in an inductor, it has some energy associated with it due to the magnetic field set up. it uses this energy to resist changes in current .then how does an inductor ...
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Why is the polarity of an inductor same as that of the source voltage when a pure inductor is connected to an AC generator?
An inductor is connected to an AC generator. Suppose no resistance or capacitor is connected to that circuit.
Then as per the lesson in khan academy, it's said that the inductor and the source voltage ...
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Is this approach of calculating mutual induction from magnetic flux Ok? [closed]
Coursework from Khan Academy, Electromagnetic Induction, - Mutual Induction worked example. For context video link - Mutual Induction Worked Example Link
Doubt link: - Image of the solved question ...
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Induced voltage in a secondary coil?
The induced voltage of the secondary coil of a transformer, is caused by the changing magnetic flux of the primary coil...
...and by decreasing the number of turns of the primary coil, the flux ...
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With induced voltage, what is the electric potential difference?
Lets say we have a closed circular loop of wire in a constant magnetic field in the (-z) direction. If I suddenly make the circular loop smaller (meaning a smaller surface area), I will induce a ...
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How to calculate the Force between a magnet & an induced dipole? [closed]
https://www.youtube.com/watch?v=xTwDZJG_W9w
In this video at 9:12 it details the potential energy of an induced dipole
Specifically
$$U=-mBcos\theta=(\frac{\chi V}{\mu_0}B)Bcos\theta$$
&
$$F_z=\...
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How to measure voltage induced in coil due to an oscillating bar magnet using null method? [closed]
Here we're trying to measure the maximum emf induced in the coil using null method.
I can understand what the book means by 'a kick'. I can't understand how this circuit works. For example, how is the ...
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Does the electric field ($E$ caused by induction) of a moving conductor in a magnetic field drop when connected to a curcuit?
We know that when a conductor moves in a homogenous magnetic field that is perpendicular to itself due to the amount of electric charge gathered on one end of the conductor( as a result of the lorentz ...
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Confusion about emf definition
The emf is supposed to be the energy gained by charges passing through a closed loop, just as in the case where we have a circuit where the potential drop equals the potential gain thanks to a battery....
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Current when inductors charging in parallel are discharged in series
We started discussing DC RL-circuits in class and were analyzing the following circuit
The scenario is the switch has been closed for a long time so the current through both 2-ohm resistors is the ...
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Why we need wires?
Imagine a cell(battery) bent in such a way that the two terminals face each other with some vaccuum in between...i hv confusion in basics..so pardon me...my question is why cant charge flow from one ...
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What is the difference between paramagnetic and ferromagnetic?
What is the difference between paramagnetism and ferromagnetism?
Before answering, I want to note my difference between the rest of the similar questions on this website: from what I think I know, ...
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Where does back emf start?
To my understanding, Back EMF will occur when a motor rotates.
This rotation inside a magnetic field will cause a change in flux, generating an EMF by Faraday's law. This EMF, the back EMF, will ...
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The effect of the inner diameter of a tube on the speed of a magnet falling through it
I have done the experiment of dropping permanent magnets through copper tubes and observing how they fall slower. With a tube that has an inner diameter close to the permanent magnet (a tight fit) the ...
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How to explain different voltage and symmetry?
Imagine a magnet is falling along the axis of a uniform metal ring, there is an Eddy current in the ring due to changing magnetic flux and the direction of the current is determined by Lenz's law. ...
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Why don't we use generators with armatures with large diameters?
From images of real-life generators they seem to have armatures that are not too large. However, from Faraday's law, shouldn't an armature with a larger diameter create a larger voltage?
Since Faraday'...
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Magnetic field produced by a changing current
When a current changes with time, it generates a changing magnetic field, according to Ampere's law.
This changing magnetic field induces an electric field, according to Faraday's law of ...
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Levitation of a permanent magnet over a conducting surface
I have seen a method of magnetic levitation where a magnet moves over a conducting surface with its north pole facing downwards (or the conducting surface moves below the stationary magnet). At a fast ...
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Magnetic field $B$ becomes infinity at the center of an electromagnetic coil?
Suppose that there is a long wire carrying a current. According to Ampere's law, there one can determine the magnetic field (B) on a circular path around the wire given its radius (R).
Consider the ...
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Problem with Faraday's Law for a Circuit with Battery
From Maxwell's equations, we know,
$$\nabla \times \vec E=-\frac{\partial \vec B}{\partial t}\Rightarrow\oint \vec E\cdotp d\vec l=-\int\frac{\partial \vec B}{\partial t}\cdotp d\vec a \tag{1}\label{1}...
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Understanding Electromagnetic Induction and Lenz's Law [closed]
I am having trouble understanding the concept of electromagnetic induction and its application, particularly in regards to Lenz's law. I am having trouble visualizing the relationship between the ...
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Induced EMF Graph
edit: EMF changes due to one of the factors, not stated, so it is not relevant to the question
{this is a past paper question regarding how the induced EMF varies in a moving conductor within a ...
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Current through a solenoid: magnetic field gives a staircase graph
We were running current through a solenoid coil with an iron core, and measuring the resultant magnetic field strength. We expected a purely linear relation for the "current-field strength" ...
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Can Faraday's law be deduced from Lorentz force?
Consider a rectangular circuit with one side being a rod of length $L$, which is free to move, and a constant magnetic field perpendicular to it. The rod moves at a constant velocity $v$, expanding ...
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Back emf for simple DC motor in radial magnetic field
With a basic DC motor setup of a single coil spinning in a linear magnetic field, the back emf produced is a sin wave, as the change in the angle between the plane of the coil and the magnetic field ...
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Uniformly polarized sphere analyzing - How to justify this method? (Griffiths 4.3)
In Griffiths 4.3 the author gives another way of calculating the surface charge of a uniformly polarized sphere.
Imagine a sphere full of positive charges and another sphere full of negative charges, ...
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Is the induced current produced on a Loop of wire by a changing exterior magnetic flux only due to this exterior magnetic flux?
Imagine a Loop of perfectly conducting wire with a Resistor with resistance R. The north pole of a magnet goes straight towards the loop and thus the magnetic flux through the Loop changes with time ...
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Force between two skew (non-parallel) straight current carrying wires [closed]
The force between two parallel straight wires carrying the same current is calculated in every textbook. The force per length changes with 1/r, r being the wire distance.
I understand that the force, ...
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Original paper of synchronous generator swing equation
I found that the swing equation of a synchronous generator was developed by Andrey Andreyevich Andronov in 1926 in a paper titled "Theory of Electric Oscillations of Synchronous Machines". I'...
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Faraday's law of induction and circuits which move and deform
In this wikipedia article there is a description of the difference between the Maxwell-Faraday equation
$$
\vec\nabla\times\vec E = -\frac{\partial\vec B}{\partial t} \tag{1}\label{uno}
$$
and the ...
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Magnetic field outside an infinite solenoid carrying time varying current
I know that this short of question has already been asked a fair amount of time, but I could not find one matching the details I am looking for.
Consider we have an infinitely long solenoid. It is ...
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Where does energy go in an induced electric field? [closed]
The induced electric field is produced due to changing magnetic field field is non-conservative in nature. However this is in contradiction to my prior understanding that all fundamental forces are ...
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In a DC motor, why would the rotor oscillate around its stable equilibrium point, had there been a constant current?
If I choose to replace the commutator in the motor with two slip rigs like those in the AC dynamo, then when the plane of the motor is normal to the magnetic field, aligning, therefore, the magnetic ...
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Torque on a elementary magnetic dipole
Let's say I have a magnetic moment due dm due to electron spinning on its axis or orbiting around nucleus. B is the external magnetic field . Then torque on the moment will be dm x B . Now if I invoke ...
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Energy Conservation when two permanent magnets attract each other
I have a very basic doubt related to energy conservation in a system of magnets. Suppose I have two magnets (bar magnets) of magnetic moment $M$ kept along the line with an initial distance $X_0$ such ...
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Would hot water induce current in a copper wire via the movement of the molecules from the heat alone?
I am a novice, so please excuse the naivety of my question.
Would hot water induce current in a copper wire via the movement of the molecules from the heat alone?
An additional follow up if that isn'...
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Can an induced current ever increase in the direction in which it is flowing?
Suppose B0 is a varying magnetic flux through a surface Σ enclosed by a line. An emf is induced and current flows in the direction of the electric field. The self-inductance is added to the magnetic ...
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Will magnetic induction by permanent magnet be different from induction by electromagnet?
I was going through the magnetic induction topic and how we can induce a conductor by various methods. While going through the electromagnet method, I thought that the conductor placed near the ...
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Can someone please clear this doubt regarding Lenz's Law?
In Lenz's Law or Faraday's Law of Electromagnetic Induction, whenever there is a change in magnetic flux in a solenoid due to an external magnetic field like an approaching magnet there is an EMF ...
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Why does Faraday's law work? [closed]
A thin bar is moving parallel to a current and we want to evaluate the tension between the two extremes of the bar.
What I did was applying Faraday's law to the bar, considering the flux of the ...
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Best way to determine direction of induced voltage [closed]
I'm trying to get a handle on how to determine the polarity of induced voltage (and by extension the direction of current) in a conductor that interacts with a magnetic field.
I've followed various ...
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Why the magnet travels through solenoid faster if we connect a bulb to a solenoid
When a magnet travels linearly through a solenoid at a fast enough velocity if the ends of solenoid are connected to each other, the induced EMF generated and Lenz Law the solenoid opposes the motion ...
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If a magnet is completely inside a solenoid, but is moving, Does this induce an emf?
I am not addressing here the case when the magnet is approaching the solenoid or when it is moving away from it. I am asking about that part of the journey when the magnet is inside the solenoid ...
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Analysis using EM momentum: metal frame moving out of uniform $B$-field
I'm trying to analyze Griffiths problem 7.11 using electromagnetic momentum. The problem goes as follows:
A square loop of side length $l$ is formed using a cylindrical metal rod of radius $r$. It ...
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In a LR circuit, Why do the current rate of increase decreases with time? [closed]
In a LR circuit, the current rate of increase decreases with time until it reaches zero eventually and that is when the current become steady. My question is why the current rate of increase decreases ...
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What leads to the conclusion that the field associated with a changing magnetic is an electric field that obeys Gauss's law?
Faraday's experiments demonstrated that when there is a changing magnetic field, stationary charges experience forces, hence there is a field (force per unit charge) associated with a changing ...
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