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Questions tagged [electromagnetic-induction]

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Which method of calculating mutual inductance to use?

I am planning to make a wireless charging device for a school project using coupled induction. However, I have found a few different ways of calculating mutual inductance for coupled solenoids and ...
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What happens when we use Faraday induction on a coil that already carries a current?

Consider the following experiment: (1) Attach a coil to a current meter, and run a magnet over that coil, measuring the current generated. This is ordinary Faraday induction. (2) (i) Attach the coil ...
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When a proton attracts an electron in the electromagnetic field is the proton “bending” the field? [duplicate]

As the question states when a proton attracts an electron in the electromagnetic field is the proton "bending" the electromagnetic field like the earth bends space time ("creating" gravity)?
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Eddy Current Pendulum and Variables of Breaking Force

I am trying to conduct an experiment about eddy currents, specifically using an aluminum plate pendulum, two permanent magnets, high framerate camera. I am altering the distance between the two ...
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Understanding the induced EMF by a magnet through a solenoid

I just started self-studying physics again after some 20 years and I'm confused by this. So assume I have a wire loop and I move a magnet quickly through it. Then there will be an induced current $I$ ...
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Where does this alternative form of Faraday's law come from?

In the Sears-Zemansky physics book on page 1007, there is an alternative way to express Faraday's law for a moving conductor in a magnetic field: $$d\mathcal E =\left(\vec v \times \vec B\right)\cdot ...
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Why using an imaginary surface is allowed when applying Faraday's law?

In a lot of problems, like a rod rotating in a constant magnetic field $B$, we find the EMF induced by the movement by defining an imaginary surface in which the rod is a part of it. Then we apply ...
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Calculation of Resistance in an isolated wire of 8 shape [closed]

Exercise:An isolated wire is used to construct a circuit in 8 shape composed of 2 circles. The superior circle has a radius of 5cm and a inferior circle has a radius of 9cm. The wire's resistence per ...
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Energy conservation in induced emf in open loop

We have a closed loop in the influence of magnetic fields of electromagnets somewhat like this. (Kindly ignore the currents and forces shown - the coil is stationary and initially no current flows) ...
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Rules to find induced emf [on hold]

So ive read that you can find the force acting on a charged particle (say positive) and the force on a conductor (say it has conventional current) by three rules- right hand palm rule, left hand ...
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Transformer output voltage

I was just curious, if the number of turns equals in primary and secondary for a transformer then this implies that $V_p=V_s$ since: $$\frac{N_p}{N_s}=\frac{V_p}{V_s}=1\space\space\space:\text{since}\...
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Induced Electromotive force in a time varying magnetic field

A square conducting loop is placed in a magnetic field with its plane perpendicular to the direction of the field. Now a thin conducting wire is placed in such a way that it divides the loop into two ...
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What happens to the impedance of the primary coil when a secondary coil is brought closer? WPT [on hold]

Im confused if the voltage and current in the primary coil changes when the secondary coil is brought closer to the first one.
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Why aren't electrical power generators housed in “floating” structures that would allow them to spin?

Every generator I've ever seen is housed in a fixed mount, and uses a rotating magnet in a column, powered by something like combustion, or wind, to generate a current through Faraday induction. But ...
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Is there a Halbach array equivalent for a coil?

Is there is a way that a coil can have one side of strong alternating field and the other side a weak alternating field? I was planning to use this and see if the efficiency of a coupled coil can ...
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Why does sudden change in temperature-gradient for magnetic steel by induction heating occur (curie-point)?

For my Bachelor-Thesis on the topic "material testing with induction heating", I am currently heating different material samples to determine the difference in induction heating of ferro-magnetic and ...
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Does a dynamic microphone produce a derivative of the input sound waveform?

Consider a common dynamic microphone, where the membrane moves an attached coil in the field of a permanent magnet. I believe that the voltage produced by the coil as the membrane is moving is ...
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Induced EMF in an inductor

In the above figure, the circuit is closed for a very long time and is then opened. It is stated that "the emf across the inductor just after opening will be very high so as to oppose the change of ...
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Electrostatic induction with a zinc plate

As you can see in the images, in the first one I am using a plastic rod rubbed with my hair to attract the pieces of paper using induction. In the second one, I am using a pure zinc plate(extracted ...
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Can we generate electricity by using rotation of wheel of a bicycle? [closed]

Can we generate electricity by using rotation of wheel of a bicycle ?
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Electromagnet, why does not coil and metal repel each other

In an electromagnet, if the electric coil induces a magnetic field in the metal bar with the same polarity as the one in the coil, should not the bar and coil repel one another, "like poles repel"?
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Variation of Induced EMF in a cross bar of a ferris wheel

The question is as follows. A ferris wheel which consists of two parallel large wooden wheels is joined together with metal cross bars as shown in the figure,is erected so that the planes of wheels ...
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current induced on an inductor modifying inducing magnetic field. Wouldn't that cause an infinite oscillating feedback?

Imagine a simple circuit with an inductor and resistor in series. Now pass thru a varying flux thru the inductor, a phi. The vary flux induces voltage on the ...
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Effects of opposing fields in coupled inductor

This is a duplicate question that I already made in the electrical engineering part of stack exchange. As I`m asking for the physics behind the effect I thought it might be worth to ask also here. ...
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Magnetic flux density compard to other definition of flux

With regards to flux i have always assumed it was defined as $$(1) Something/m^2s$$ For instance $Luminosity/(4\pi r^2)$ Is an example of radiation flux. Why then is faradys law often cited as the ...
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Confusion regarding torque given by M×B

The magnetic torque acting on a loop of magnetic moment M placed in a magnetic field B, is given by τ=M×B. My question is, about which axis does this give the torque about? Is it the instantaneous ...
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Can you generate 3-phase AC power from linear motion?

If you have reciprocating linear motion (such as a piston moving up and down in a cylinder), is it possible to generate three-phase AC power from it without converting it into rotary motion first? I ...
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What is meant by “changing magnetic field”

At first I thought it was the consequence of an object moving from an area of high to low or low to high flux density, but that doesn’t help understand what is meant by “a changing magnetic field” ...
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Current sources and conservative electric fields

Suppose a current density ${\bf J}({\bf r},t)$, for which $\nabla \cdot {\bf J} =0$, is compactly supported on a 3D region $R_1$ in vacuum. In general it can produce a nonzero electric field ${\bf E}({...
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How does an alternator produce AC?

As an alternator’s coil moves, one side of the coil induces a voltage and thus a charge flow in one direction However, simultaneously the other side of the coil induces a voltage and charge flow in ...
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Does the state of curl of the $E$-Field at a point adjust itself instantaneously as soon as $B$ begins changing at a fixed rate, or is there delay? [duplicate]

Faraday’s Law () states that a time-changing magnetic field vector induces a curl of the Electric field around that point. However it does not specify how quickly the necessary spatial gradient is ...
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How can EM waves propagate indefinitely when they really are oscillations of electric and magnetic fields?

I can't claim that I've fully grasped the science behind EM waves, but as far as I understand, EM wave is basically oscillations of electric and magnetic fields kinda switching back'n'forth and ...
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Relationship between self induced EMF, inductance and current's rate of change

I'm kind of confused about the principles of self induction; Does change in current represent the change in the net current (battery's current + induced current) or just battery's current? among the ...
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Can $F=qvB$ be applied to a solenoid and a parallel moving magnet?

If you take a scenario like this, Charge gathers at either end, and if you could somehow form a complete circuit without there being a canceling effect, there would be a current flowing. This makes ...
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Induced Electric Fields and Faraday's Law

I'm an undergraduate student and we just covered Faraday's law. However, I am still confused conceptually about a few things: Faraday's law states that $\oint_{\partial\Sigma} \vec{E} \cdot \vec{dl} =...
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Does back E.M.F. create a second back E.M.F. which creates a third back E.M.F. and so on? [duplicate]

Does back E.M.F. also generate a back E.M.F. of it's own? If so, why do I not hear this discussed? Is this because it has a very small effect, i.e. it lasts a small amount of time or it has a small ...
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In a D.C. motor, is the Lorentz force on the conductor directly proportional to the back E.M.F.?

In a D.C. motor, when there is a current in the conductor a magnetic force arises on the conductor. If there is no load on the D.C. motor the magnetic force will move the conductor. With the motion of ...
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A changing magnetic field passes through a wire loop but the loop itself is not in the field. Is an EMF induced in the loop? [duplicate]

$$\nabla \times \vec{E} =-\frac{\partial{\vec{B}}}{\partial{t}}$$ Applying Stokes' theorem: $$\oint_{loop} \vec{E} \cdot d\vec{l}=\int_S -\frac{\partial{\vec{B}}}{\partial{t}} \cdot d\vec{S}$$ ...
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Description of the spiral path of an electron under the influence of a magnetic field

Moving charged particles in an external magnetic field (of course non-parallel to each other) get deflected into a spiral path. For a calculation of this phenomenon it is not sufficient to use the [...
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When does back EMF equal work done by the magnetic force, for a conductor in a magnetic field?

I've come across this statement: "A current carrying conductor moving through a magnetic field induces an EMF. If a current carrying conductor of length L is put in a magnetic field with flux ...
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Counter Torque in Electric Generator

I am going to use some sort of “dynamo” or electric generator component to generate electricity from the flowing drilling fluid. However, the effect of the magnet rotating within an electrical coil ...
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1answer
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magnetic flux and EMF - in an open circuit

Lets say I've got a rectangular conducting frame resting inside a changing uniform magnetic field. the magnetic flux (Φ) is: the vector of the magnetic field cross product the vector of the area of ...
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1answer
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A question regarding Faraday's integral law

This might be a quickly phrased question so I apologize if I've missed something trivial in my understanding. Faraday introduced the concept of fields to explain the phenomenon of action at a ...
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Where does this form of the induction law come from?

I am currently studying a eddy current disk break and came across this promising paper (PDF, princeton.edu) from 1942. However, in the first formula a suspicious $4\pi$ appears before the current $U(...
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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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1answer
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Induced current due to induced current

Say we have a square coil and a change in magnetic flux is created through the coil. Thus inducing a current in the coil whose magnetic field opposes this change inside the coil. If we assume(for ...
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Order of Magnitude for Photon Induction

What does magnetic induction look like when we imagine just one photon passing by? I'm imagining some sort of coil wrapped around the edge of a waveguide or something so that it picks up some of the ...
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How to induce large current in a flexible wire

I have not tested this method in the lab or anything, but based on what I know about electrodynamics I would say the following set up could work: I would take two straight flexible free-of-current ...
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Would the voltmeters give different readings in a circuit with induced current?

$\def\vE{{\vec{E}}}$ $\def\vD{{\vec{D}}}$ $\def\vB{{\vec{B}}}$ $\def\vJ{{\vec{J}}}$ $\def\vr{{\vec{r}}}$ $\def\vA{{\vec{A}}}$ $\def\vH{{\vec{H}}}$ $\def\ddt{\frac{d}{dt}}$ $\def\rot{\operatorname{rot}}...
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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 ...