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1answer
38 views

Calculating the induced emf without knowing the change in magnetic flux [on hold]

A conducting rod of length $\ell$ moves on two horizontal frictionless rails, as in Figure P20.30. A constant force of magnitude 1.00 N moves the bar at a uniform speed of 2.00 m/s through a ...
0
votes
1answer
68 views

Electromagnetic induction creates a current with a Lorentz force?

The induced electromotive force (emf) and thus current in a circuit is equal to the time rate of change of magnetic flux link with the circuit. The direction of the induced emf or the current is such ...
2
votes
0answers
33 views

Induced emf in a circular conducting wheel

Consider a conducting wheel with $N \in \mathbb{N}$ spokes which is completely in a homogenous magnetic field $\vec{B}$ perpendicular to the wheel plane. ...
0
votes
1answer
20 views

Why can intramedullary rod heat with MRI?

It is said, that steel rod inside body, like funeral nail, can heat while magnetic resonance imaging (MRI). But why? Isn't MRI scanner use constant magnetic field? If the heating effect is caused by ...
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0answers
56 views

Electrical field of the coil

Take the case of two coils, first one connected to alternating current supply, and the second one connected to load. First coil creates magnetic field, and electric field is reduced by anti-emf ...
3
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0answers
15 views

If you toss a handful of confetti onto a comb, why does some of it stick and some of it fly away?

My guess is some paper pieces happen to be charged with the opposite charge compared to the comb, so they are attracted, but once they touch the comb, their charge is neutralized. But the comb is ...
2
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4answers
144 views

Application of Kirchhoff's laws in circuits with inductors

As we know,the Kirchhoff circuit laws are applicable for conservative electric fields. Now it is applicable for circuits where inductors are present but the field there is not conservative. So how ...
0
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1answer
34 views

Direction of EMF

I was reading electromagnetic induction and came across EMF.Now in my text book as the theory has been developed ,they have many a times talked about direction of EMF. But they have not clearly ...
-1
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4answers
117 views

Why uncharged particles do not feel the Lorentz force? [closed]

Why uncharged particles do not feel the Lorentz force? Please do not answer with the formula $ \vec F = q\left( \vec E + \vec v \times \vec B \right) $. Edit after an answer which is an circular ...
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2answers
60 views

Is the electron magnetic moment responsible for the Lorentz force?

My question about the sum of the electrons' magnetic moments in a wire(What is the sum of the electrons' magnetic moments in a wire?) had an answer which disappeared later. The answer was - if I ...
1
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1answer
52 views

What is the sum of the electrons' magnetic moments in a wire?

The electron has a magnetic moment. This magnetic moment will be influenced in a electric field; the magnetic moments will be more or less aligned. During the movement of an electron in a wire under ...
-1
votes
1answer
37 views

Direction of compass needle nearby an electric wire

Let through a straight wire flow an electric current. Using a compass needle how the needles tip will be directed to the wire? What happens when we switch the current direction and approach the needle ...
0
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1answer
65 views

Asymmetry in magnetic field direction of an electric wire

The simplest magnetic field is that of an infinitely long wire with uniform current. It does enjoy radial symmetry about the wire and has the variation as 1/r. To find the direction of the resulting ...
0
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1answer
23 views

Can non-conductive materials can be grounded by a wire?

Suppose that I comb my hair. The plastic comb would become negatively charged and would attract small paper pieces. But if I touch the comb in bare hand and in bare foot standing on the ground, or if ...
-2
votes
1answer
66 views

Some general questions about static electricity ( ex : Combing the hair ) [closed]

We know , static electricity is built up when i comb my dry hair. what type of charge is gathered in comb & what type of charge in hair ? ( i.e. + or - charge ) why would charges would gather ...
2
votes
1answer
70 views

Teflon and induction cookware

I remember once getting new Teflon (non-stick) cookware; however, when I tried this new cookware on my induction cooker the cookware did not heat up. My regular steel cookware worked just fine on the ...
1
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0answers
39 views

Explain the infinitude of magnetic flux about a finite length of wire

Ok so it is clear the flux caused by an inductor is limited. If I integrate about a flat spiral inductor I will find that the flux lines going up are a fixed quantity. Since every flux line going up ...
1
vote
1answer
144 views

Why is there a voltage drop across a superconducting inductor?

If there is no electric field inside a perfect conductor, then why is there a potential difference across an (superconducting) inductor?
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0answers
23 views

Does the skin effect and the proximity effect cancel each other out?

I'm interested in how the Skin Effect and the Proximity Effect interact with each other. From what I can understand: The Skin Effect is when AC current 'collects' on the skin of conductors due to ...
1
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0answers
46 views

Remotely changing superconductor levitation height?

I want to be able to modify the height of a quantum locked superconductor. My original plan was to levitate the superconductor over an electromagnet and modify the current to said magnet (increase the ...
5
votes
1answer
139 views

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 ...
2
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1answer
28 views

Cooling induction current generation

We know that conducting materials can be heated by electromagnetic induction. Is it possible to generate current using a cooling process?
0
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1answer
51 views

Magnetic force and terminal velocity of falling loop and falling disc?

According to my textbook, if a square loop with mass $M$ is allowed to free fall (with a magnetic field at the bottom side and as soon as the square loop is dropped then the area inside the loop ...
1
vote
1answer
71 views

Which is more efficient Water heating method : Electric heating coil OR Induction stove? [closed]

Which is more efficient Water heating method : Electric heating coil Vs Induction stove
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2answers
64 views

Induction on a circuit with switch

I have the following circuit: It is subject to a steady, time-invariant magnetic field which points out of the paper. At $t = 0$, the switch closes. I thought that the magnetic flux would decrease ...
0
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1answer
71 views

Voltage across an inductor contradicts Lenz's law?

Imagine a simple circuit consisting of an alternating current source connected to an inductor. Assume they are connected in the following fashion: AC source - terminal A - Inductor - terminal B - AC ...
0
votes
1answer
110 views

How do I create a direct current with a magnet? The magnet is not to be moved in the direction of the wire [closed]

How do I create a direct current with a magnet? The magnet is not to be moved in the direction of the wire. In fact I'm looking for the contrary to the drawing from ...
3
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0answers
67 views

Attraction and repulsion of electron spin ups and electron spin downs

Alright, we know that copper is a diamagnetic material, which has paired electrons. These paired electrons have different spin. I'm specifically interested in what is going on with the electrons in a ...
0
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1answer
40 views

Signal Induction in a Wire due to Alternating Current

I wanted to make sure I understand induction well enough. Assume we have two wires running parallel to each other. Wire A has a signal of $f(t)$, wire B has a signal of $\hat{f}(t)$. Let's connect a ...
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1answer
44 views

Current and emf in a transformer

In the book Fundamentals of Physics by Halliday, Resnick and Walker(Extended)(6th edition), in a an ideal transformer it is written that the current induced in the secondary coil induces an opposing ...
1
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1answer
35 views

Reasoning transformer identity for currents [closed]

When looking for reasons for the Transformer Identity for Currents with a short secondary circuit $$\frac{I_2}{I_1}=\frac{N_1}{N_2}$$ I find two common answers: Both coils create the common ...
0
votes
1answer
67 views

Why Change Of Magnetic Flux Induces Current In circuit?

Why change of magnetic flux with the time through a coil induces current in it? Please tell me that what happen to charge in the coil if the magnet or electromagnet wave around this? Also, why a ...
0
votes
1answer
35 views

Predicting Faraday's law, Changing Fields

Are there other equations that we can predict Faraday's law from? I know that each of Maxwell's equations are 'fundamental', but I feel like Gauss's law and Ampere's Law are very "nice", and for some ...
2
votes
3answers
78 views

Faraday's Law - recursive?

So we know that the EMF is induced by change of flux. The thing that was always confusing me is the following: we start changing the magnetic field which in turn induces electric field which makes ...
1
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0answers
16 views

How might inducted current/ voltage in multiple coil layers connected in parallel behave?

This is a branch from this question. In the event that two or more layers are connected in parallel - would the energy created across each layer likely be significantly less? In the event of (say) ...
1
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1answer
48 views

How might eddy currents and terminal velocity be broken down?

This is a branch from this question. With regards eddy currents and terminal velocity I have located a homework question but would appreciate more detail (and translation of the symbols described ...
0
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1answer
54 views

Magnetic Induction - How would different coil configurations affect the outcome?

This is a branch question (from this question) related to magnetic induction: These deal with how different configurations of coiled layers might affect the outcome: If one were to bundle multiple ...
-1
votes
3answers
48 views

Can the potential difference produced in Van De Graff generator used to generate electric current?

If this machine can build up high voltages of order of millions of volts, can we use this volt the generate current of electrons? The building up of potential difference can result in electric field. ...
3
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0answers
89 views

Faradays Law: How Does Curl E Change Over Time In a Coil?

I think I am currently making a mistake regarding my interpretation of Faraday's Law. $\vec{\nabla}\times\vec{E}=-\frac{\partial\vec{B}}{\partial t}$ Assuming we have an electric field $\vec{E}$ in ...
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0answers
33 views

Transformers rate equation

Going back to transformers after some years I realize they hide a possible missconception I'm not sure I really understand. It is not easy to find a full derivation of the well known relation ...
1
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2answers
288 views

Why does the induced EMF oppose the change in magnetic flux? Lenz's Law question

Can anyone explain to me why the induced magnetic field will oppose the change in magnetic flux? Is it an energy thing? I know that the induced emf is $$ emf= - \frac{d\phi}{dt} $$ but my book ...
0
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0answers
31 views

Self-inductance of a toroidal inductor

I am trying to determine the self-inductance of a toroidal coil of mean radius $R$ with $N$ loops of radius $a$ with a current $I$ flowing within them. I have calculated the magnetic field by noting ...
0
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2answers
107 views

Magnetic field by a solenoid?

I am really not able to understand why is it that the current,while finding the magnetic field in the solenoid (ideal one), is not $I$ the current flowing throught the solenoid but $nI$, where $n$ is ...
1
vote
2answers
574 views

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 ...
1
vote
1answer
225 views

Current induced in coil when magnet falls through it?

So I know that magnetism can be obtained from the combination of electric fields and special relativity. I am familiar with the way one can derive the magnetic field of a current carrying wire felt by ...
1
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2answers
77 views

Lenz's law and bar magnet falling from some height above

I am reviewing my electromagnetism studies and I became confused with where energy of induced emf due to Faraday/Lenz' law come from. Suppose that there is a curved track that starts with some height ...
0
votes
1answer
107 views

Induced current and Ohm's law

I am trying to explain this problem: A circular conducting loop composed of N turns of wire has a radius of r and a total resistance of R. Perpendicular to the plane of the loop is a magnetic ...
1
vote
1answer
65 views

Energy in a Solenoid?

Consider a circuit consisting of a battery, a resistor and a solenoid inductor. Then, the emf $\mathcal{E}$, is defined as: $$\mathcal{E} = L\frac{di}{dt} + iR$$ Multiplying both sides by ...
0
votes
2answers
138 views

Why is no EMF being induced in this ring passing through a magnetic field?

The book's logic is that there is no induced EMF because flux is constant as it passes through the magnetic field. Which makes sense, but this seems counter-intuitive to what I previously learned. ...
1
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0answers
77 views

Finding the induced EMF on a bar - Faraday's law

I have a couple of questions about the following problem: A conducting bar of length L moves with velocity v, in a rectangular region with a uniform and stationary magnetic field B_1. Near the bar, ...