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3answers
38 views

Currents induced by rotation of a coil about magnetic field lines

If the coil on the left is rotated about the magnetic field lines, will there be an induced current? I know that the flux concerns only the component of the magnetic field perpendicular to the ...
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3answers
51 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. ...
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2answers
559 views

Measuring voltage drop from induced current

I'm having trouble connecting voltage drops and induced current. Imagine you have a triangular loop make up off three resistors. You place this loop in a constantly changing magnetic field. This ...
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2answers
131 views

What is the area in Faraday's law if we have only a piece of metal moving in a magnetic field?

If a piece of metal of length $l$ is moving with a speed $v$ in a region where there is a uniform magnetic field $B$ perpendicular to it, there will be a potential difference across its terminals ...
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2answers
75 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 ...
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2answers
123 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 ...
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1answer
230 views

Would there be EMF induced in our body due to electromagnetic radiations?

The experiments of innovative Faraday and Joseph Henry in USA, conducted around 1830, demonstrated conclusively that electric currents were induced in closed coils when subjected to changing magnetic ...
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1answer
21 views

How to induce charge in glass bubble particles ?

I am trying to induce charge ( + or - ) in the glass bubble particles ( manufacturer 3M 25-32 micrometer) . Can anyone tell me how to effectively charge them. I have tried placing these particles in a ...
1
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1answer
61 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 ...
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1answer
199 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?
1
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1answer
238 views

Is it possible to use induction ampermeter to measure power consumption of electric water heater and dryer?

I hope this practical question is not OT and not too trivial for this forum. I am renting an apartment in a duplex with a shared water heater and dryer. Turns out, both water heater and the dryer are ...
1
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1answer
688 views

Back motor effect of loaded generators?

The back motor effect (see Counter-electromotive force) is the counter torque which opposes the rotational motion of the coils in a generator when the generator is under load. The back motor effect ...
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1answer
21 views

If we rub glass particles with paper , will there be any charge induction in glass particles?

If we rub glass particles with paper , will there be any charge induction in glass particles ? I know if you rub with silk they do get charged, but i want to know specifically for glass and paper.
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1answer
27 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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votes
1answer
74 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
votes
1answer
183 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 ...
0
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1answer
89 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 ...
-2
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1answer
56 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 ...
3
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0answers
23 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 ...
3
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0answers
84 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 ...
3
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0answers
120 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 ...
3
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0answers
252 views

Finding the terminal velocity of a magnet dropped in a solenoid

We have to find proportionality of the terminal velocity with the factors of the system: Plot: a small dipole(mass $m$) with dipole moment $\mu$ is dropped in a long solenoid (radius $r$, ...
2
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0answers
39 views

Induced current created by a magnet falling in a copper tube?

One of the educational demos often shown in schools is to drop a high strength neodymium magnet down a length of copper tube. It takes a considerable time to exit the tube because as it falls it ...
2
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0answers
43 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. ...
2
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0answers
159 views

Absolute permittivity and permeability of free space

I'm reading about the propagation of EM waves in vacuum. We define the wave equation using two constants: $\epsilon_0$ and $\mu_0$. Of course they are absolute permittivity and absolute permeability ...
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0answers
75 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 ...
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0answers
47 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 ...
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0answers
26 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
57 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 ...
1
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0answers
20 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) ...
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0answers
89 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, ...
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0answers
81 views

Hertzian dipole in time varying electric field

Suppose we place a Hertzian dipole (short, ends loaded with capacitance) in a time varying electric field $\vec{E}\left(t\right)$, with magniture $E\left(t\right)$ and direction as shown in this ...
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0answers
12 views

Induced electric field due to a moving wire

An infinite wire carrying a constant current $I$ in the $\hat{z}$ direction is moving in the $y$ direction at a constant speed $v$. Find the electric field, in the quasistatic approximation, at the ...
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0answers
37 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 ...
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0answers
46 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 ...
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0answers
41 views

Would a $50\: \mathrm{Hz}$ spinning magnetic plate in front of a human generate harmful current?

We know that spinning magnetic plate will generate current inside any wire. so if we stand before 50Hz spinning magnetic plate, then, does that 50Hz spinning magnetic plate in front of us (human body ...
0
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0answers
45 views

Eddy Currents in Metal Implants

Related: Why is stainless steel a poor conductor of electricity? I recently had a metal implant, and I'm psyching myself out- should I be considered at all with eddy currents in the implant? I feel ...
0
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0answers
61 views

Blocking electro-magnetic waves between two near field antennas

Its been a while since I studied physics, so pardon my ignorance. I have two near field antennas. The range of the antennas is about 2-3 cm. I am looking for a way where I can block and unblock the ...
0
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0answers
337 views

What is the current induced in a straight wire when a magnetic field is turned from on to off?

Consider a straight wire which runs along the y-axis. A B-field exists which is uniform and only in the x-direction: $$\vec{B}=(B(t),0,0)$$ The B-field at time $t_0$ is 'switched off' in ...