# Questions tagged [electromagnetic-induction]

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### How can classical physics explain what happens when a charge fixed by two other charges experiences a magnetic force?

I have invented this little problem to help me understand the magnetic force better. Imagine 3 positive charged all on a line. The first charge is separated by distance D from the second charge, and ...
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### Moving charge thought experiment paradox

Let’s say you have a moving charge, relative to a stationary observer. They measure that it has an electric field $E$ and a magnetic field $B$. Because the observer is stationary, they experience no ...
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### Electrostatic induction - how to quantify it with a theoretic integral expression or like?

Assume that a certain distribution of charges $\rho$ generates an electrical field $E_{ext}$ in the surrounding space. We also note the corresponding generated potential $V_{ext}$. Assume furthermore ...
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### What does the work to induce an electric field?

When a conducting rod moves orthogonally through a magnetic field, charges in that conductor experience a force that is perpendicular to both the magnetic field and their velocity. Let's say that ...
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### Complete expression for current induced in a conductive loop

What is the complete general expression for the electric current i induced in a conductive loop of inductance L and resistance <...
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### What will happen if current can travel through the soft iron core of a transformer?

(Here's my understanding just in case if I misunderstood something) I understand that for order to induce a voltage on the other side of the transformer or in the secondary coil even though there's no ...
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### How does the diameter of a coil affect the time it takes for a magnet to pass through?

I'm thinking of doing an experiment based on the question. But I have no idea if it will work. I've tried finding things on the internet, but they all talk about the diameter of the wire, not the coil....
25 views

### Source of the electric field in a loop falling through a constant magnetic field

Figure shows a loop falling down through a constant magnetic field which points into the screen. Due to the Lorentz Force a magnetic force is present on the top part of the wire which pushes the ...
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### How can one write $\varepsilon=I R$ for a loop moving in a constant magnetic field?

A loop is moving down with some part of it in a constant magnetic field pointing into the screen as shown. We know the emf due to magnetic force is $\mathcal{E}=-\frac{d \Phi}{d t}$. If the loop has a ...
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### Is it possible to find potential difference between two point in case of induced EMF created by a time-varying magnetic field?

Q: There is a uniform time varying magnetic field in a circular region as shown in the figure. find out the potential difference across 2 point along an elliptical path as shown in figure. As far as ...
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### How to find potential difference between two points in a loop in case of motional emf? [closed]

Given below is a question in my physics textbook. A rectangular frame of wire abcd has dimensions 32 cm×8.0 cm and a total resistance of 2.0 Ω. It is pulled out of a magnetic field B=0.02 T by ...
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### Delay between the change of external flux and induced current

How long does it take for the current induced in a shorted superconducting solenoidal coil to reach its maximum value when a permanent bar magnet rotates inside that coil by $180^\circ$ in time $t$? ...
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### Current induced in a superconducting coil

Does the magnitude of current induced in a shorted superconducting coil depend on the external flux's rate of change dΦ/dt ? Assume that an external flux source (Φ) attempts to change flux inside that ...
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### Behaviour of inductor (understanding equation)

If an inductor is connected to a.c.source (thinking no resistance is there), and if we travel across circuit there is voltage drop, and it is said $$V=L\frac{di}{dt}$$ If voltage applied equals back ...
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### Induced EMF due to stationary coil

why current gets induced in the stationary coil whenever magnetic field associated with it changes. we usually give answers to these questions in terms of like, according to faraday's law that ...
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### Why is magnetic flux conserved in a magnetic field [closed]

Why is magnetic flux conserved in a magnetic field? What rule tells this?
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### Why does nature “abhor” a change in flux?

I am talking about this particular statement by Lenz who made the Lenz law for finding directions of induced EMI - "Nature abhors a change in flux".
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### Can application of external force cancel off the emf induced due to external magnetic field in a charged conductor?

If we take a charged conductor in a time-varying magnetic field and apply a varying force on it so that the Lorentz force on it is cancelled by the varying force, will an emf still be induced on the ...
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### How to determine the direction of inductional current in the ring? [closed]

The permanent magnet is being moved away from the ring. How to determine the direction of the inductional current in the ring? Here's what I've tried. Magnetic field lines go from the North pole of ...
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### When a particle changes its spin orientation is it instantaneous?

A change of magnetic field caouses an electric field and an associated potential which is as high as the time derivative of the magnetic field.So is it possible that the change of the spin should be a ...
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### Does an non-moving electrically conductive metal become magnetic in a full-DC offset AC field?

Let's assume an electrically conductive object made of metal is static and does not move. Then let's apply an outer electric field. Clearly, a constant DC field would not induce any currents and ...
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### Gas ionizing reactor

What would happen if you ionized a gas inside a coil of wire with high voltages? Please correct me if I misunderstood something, but my interpretation is the following: If you reach the diaelectric ...
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For the case of an ideal transformer, I understand that the voltages are proportional to the turns ratio. $\frac{V_1}{V_2}=\frac{N_1}{N_2}$ since I assumed the transformer to be ideal: $V_1I_1=V_2I_2$ ...
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### Is this analogy of Induced emf correct?

I have searched PSE (and many other sites on internet) for the theoretical reason of induced emf. All I got was that the phenomenon of Induced EMF is experimental fact and can only be mathematically ...
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### Faraday's Law or Kirchoff's Loop rule?

$$\mathbf{B}=\begin{cases} B_{0}t ;t \in [0,T]\\ B_{0}T ;t>T \end{cases}$$ Assume negligible resistance for the connecting wire and other necessary constants. Should I use Faraday's Law or Kirchoff'...
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### What is the area $A$ in the magnetic flux for AC generator and a coil?

I am getting confused with what area do you use in AC generators and coils. Let me explain: in an AC generator, there are two coils that rotate. When using the equation - magnetic flux $= BA\cos(x)$, ...
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### Is emf equal to or proportional to the rate of change of magnetic flux?

I'm slightly confused about Faraday's law. Is it directly proportional or is it equal to the rate of change flux? If it is proportional, what's the proportionality constant? It might seem like a ...
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Consider two parallel conducting frictionless rails in a gravity free rails parallel to x axis. A movable conductor PQ( y direction) of length $l$ slides on those rails. The rails are also connected ...
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### Current Induced in a Superconductor

I am trying to solve problem 7.43 in Griffiths, where a Superconducting Sphere is cooled below its critical temperature, and I am asked to find the induced current. In the first few parts of the ...
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### Electric Field in a time varying uniform Magnetic Field

Consider the above the cylindrical region containing a time-varying uniform magnetic field. I have noticed that while calculating the magnetic field at any distance 'r' from the center, we take up a ...
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### A misunderstanding concerning self induction of an inductor

If there is an inductor in a certain electrical circuit, from Faraday's Law we know that $$\oint \vec{E} \cdot \vec{dl} = -\frac{d\phi_{magnetic}}{dt}$$ I see everywhere that when doing this line ...
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### Will current be induced in the conducting loop in this scenario?

The question is simple. We know induced emf in a conducting loop due to a changing flux is given by $$E = -\frac{d\Phi}{dt}$$ My question is if the flux is changing only in a small part of the loop ,...
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### Why Doesn't moving a wire near earth generate electric current?

Why Doesn't moving a wire near earth generate electric current as the earth is a big magnet and we are changing the magnetic field by moving the wire?
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### Can Faraday Law be applied to a loop with some twists and turns in it?

Consider the above question. I have been able to solve the question understanding area vector of A and B are opposite in direction. However I have some conceptual doubts. In Faraday Law, when we say ...
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### Heat dissipation inside an extremely high inductive coil

Is it possible that for an extremely high inductive coil the oscillation paths for the electrons are so small that they can 'live' between atoms of the copper lattice without touch them and so not ...
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### Can non-harmful eddy currents be used to heat water? [closed]

I think after 'googling' some web sources that eddy currents are strictly localized in a volume of iron surraunded by a loaded inductive coil so can not cause an electric shock to a person while the ...
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### Potential difference in a conducting ring placed in a changing magnetic field

Say we have a conducting ring of constant radius r, placed in a perpendicular magnetic field, which changes at a constant rate dB/dt. Now, there will be an emf induced in the ring given by ℰ=-d(BA)/dt=...
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### Faraday induction law - surface clarification

Faraday's law states, $$emf = \oint \mathbf{E} \cdot \mathrm{d}\boldsymbol{l} = - \frac{\mathrm{d}}{\mathrm{d}t} \int \mathbf{B} \cdot \mathrm{d}\mathbf{s}$$ The typical surface we see used to ...
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### Two bar magnets taped together in opposite direction (north-south) dropped through a coil

I conducted an experiment where I have to align two bar magnets so that both ends are “north - south” and tape them together. Then, I have to drop them through the center of a coil of 400 turns ...
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### EMF on moving bar when it is shielded from magnetic induction

Fig.: Conductive bar moving along a conductive rail. The bar is shielded from magnetic induction by a highly permeable, insulated cylinder. I know if a conductive bar moves on a conductive rail with ...
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### Analytically understanding wireless power transfer

https://youtu.be/M8aZoM9p43k This YouTube link shows a experiment I quickly made. Two resonant lc circuits that use magnetic fields to wirelessly light up a led. I manually found the best frequency ...
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### Current in a purely inductive circuit

To maintain the current in the purely inductive circuit why is the applied alternating voltage is equal and opposite to the induced e.m.f in an inductor . I'm unable to understand this point Why isn't ...
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### Does an AC circuit transmitting 20hz and 2khz audio frequency carry twice as much energy as a 40hz and 4khz frequency?

If a guitar pickup uses electromagnetic induction to induce AC current into a wire, does the low fundamental frequencies in that current carry more energy than the higher frequencies? This is not a ...
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### Why Lenz's law works?

When we move a magnet towards a coil, current is induced in it. Magnetic field too develops around it. Since there is interaction of both magnetic fields(that of magnet and coil), there is magnetic ...
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### Diamagnetic effects in matter

According to my physics book, all materials could manifest diamagnetic effects (it is a consequence of Faraday's law of electromagnetic induction). However due to the presence of intrinsic magnetic ...
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### Does an electric field induced by a time varying magnetic field has an energy associated with it?

Consider a time varying magnetic field. This induces an electric field upto infinity as per Faraday law and other related laws. Is energy stored in this induced electric field? If so, what kind of ...
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### Parameterization of 2D rotating surface for finding magnetic flux (+ induction)

Before you link: I have asked this question on Mathematics stack exchange and it's fallen flatter than the flat-earthers so I'm duplicating it here hoping somebody will help. So the problem is that we ...
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### Energy Conservation: How is Heat generated in a loop with Time Varying Magnetic Field through it?

Consider a circular loop kept in a time-changing magnetic field. We know, via Faraday Law, that EMF is induced across the loop and hence a current appears in the loop. Let there be some Resistance ...