Questions tagged [electromagnetic-induction]

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if an oscilating LC circuit without antenna could produce electromagnetic waves since there is changing electromagnetic field?

Just shown as the above picture, if the right part removed, would electromagnetic waves still be produced near the inductor and what the changing electromanetic field are in this situation? I used to ...
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26 views

Current induced in straight wire by a moving point charge

I have a straight wire that is grounded through a resistor. It initially has no current flowing through it. A point charge $q$ moves past the wire with velocity vector $v$ relative to the wire. How ...
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Why we take the element $ds$ in self inductance of coaxial cable

I watched on a derivation of coaxial cable and when we want to calculate the self inductance per unit lengh we first find the flux of the magnetic field,so we take the integral $\int_{a}^{b}\vec{B}\...
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Regarding Faraday's law as written in Pozar's Microwave Engineering

We can clearly see in page $6$ of Pozar's Microwave Engineering Faraday's law written under this form $$\nabla \times \bar{\mathcal{E}}= \frac{\partial \bar{\mathcal{B}}}{\partial t}-\bar{\mathcal{...
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Induced emf expression in Faraday's law of induction

Magnitude of induced EMF in a loop is given as $|\frac{d\phi}{dt}|$. If the loop has n turns then induced EMF is given as $|n\frac{d\phi}{dt}|$. As we can consider each turn to be a battery which is ...
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Explain the reason behind electromagnetic induction of closed loop wires

Don't mistake me for asking why Faraday's law of induction works fundamentally. (I know there exists duplicates if that was my question). Firstly, I can explain why when a straight infinite wire moved ...
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Is it possible avrage power on resistor in circuit is zero?

Is it possible that if I have a current creat by magnetic field inductance, I will get that the average power that consume to heat on a resistor is zero? and if yes what does it mean?
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Black Body emission - Coupling of $E$ and $B$ field

I do not understand how a black body emits electromagnetic radiation. I assume that heating a black body creates moving charges which induce a magnetic field. But where is the $E$ field part of the ...
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Induction equation - derivation

Where this minus disappear, please? Source: https://en.wikipedia.org/wiki/Induction_equation
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Will constantly passing a track of magnets through a copper coil generate a DC?

Just a little experiment. If I had a long circular line of magnets connected to each other and spun the magnets so that there would always be magnets running through a coil of copper, is a current ...
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Can I use a wireless charger to heat a pan? [closed]

By my understanding, wireless chargers and induction stoves work the same way. If so, can I use a wireless charger to heat a pan? Or maybe some aluminium foil? If so, how much heat can it generate? ...
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Does Mutual Inductance Affecting my Headphone? [closed]

I am hearing small murmuring sound in my headphones which are connected to my laptop only when my electricity is fluctuating.My laptop charger is disconnected from mains.The headphones wire is close ...
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What was Faraday's experiment's of induction?

I'm searching about the experiments, which Faraday has done in order to discover the electromagnetic induction phenomenon. I didn't find what I need on google scholar nor google books. Can you ...
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24 views

Current in a generator

According to the Faraday law, voltage will be induced in the generator when the the loop will move in a magnetic field. This voltage will cause the current in the circuit. My question is Do ...
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Proximity effects at high frequencies

I was trying to understand Skin and Proximity Effects in conductors when I stumbled onto this. I'm using QuickField 6.4 for reference. According to theory, when I place a permeable material, such as ...
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Electromagnetic waves produced from a sinusoidal current

Say I have an oscillating sinusoidal current flowing on the z-axis (say $I_0\sin{\omega t}$), in a straight line conductor. This current produces an alternating magnetic field in the azimuthal ...
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On the direction of the induction current

Some time ago, I started looking back at my notes from high school and now I have a question regarding the direction of the induction current I've been thinking about for days. It might be too easy ...
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1answer
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Electromagnetic Induction experiment with solenoid

The experiment is as follows A solenoid is connected to a galvanometer and a magnetised iron rod is passed through it. (the apparatus is not ideal, and there is no zero error in the galvanometer) I ...
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Confusion regarding a few sign conventions in appyling faraday's law to inductive circuits

In the mit ocw lecture by Prof. Lewin on EMI, He quotes a few statements from here to couple of seconds of the lecture. I am confused why the sign of $L\frac{dI}{dt}$ changes, when we go around and ...
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Two conducting rods move on top of two conductors in a non-uniform magnetic field. Problem regarding the EMF of the circuit formed

An infinite length conductor (1) with electric current I creates a magnetic field $B=\frac{μ_0I}{2πr}$, where r is the distance from the conductor. Two parallel long wires, (2) and (3) (in the ...
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What happens to an inductor if the stored energy does not find a path to discharge?

Suppose an inductor is connected to a source and then the source is disconnected. The inductor will have energy stored in the form of magnetic field. But there is no way/path to ground to discharge ...
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1answer
18 views

How does the induced current flow through the coil

Take a circuilar coil and a rectangular coil. Change magnetic field through them. Due to circular symmetry electric field of same magnitude is induced all over the coil.But in rectangular coil there ...
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16 views

Electromagnetic induction in a system

In a two body system both carrying current thus constituting a magnetic field, so will the mutual inductance of the system be equal to the mutual inductance due to body 1 on body 2 and vice-versa. If ...
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47 views

Self-induction in Transformer

In a transformer, If the circuit of the secondary coil is opened, then the emf of the source equals the induced emf by self induction in primary coil So what makes them equal? Is there a law that ...
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1answer
24 views

Lenz's Law - Is the force exerted to oppose the motion always a magnetic force?

For electromagnetic induction, Lenz's law states that "the current induced in a circuit due to a change in a magnetic field is directed to oppose the change in flux and to exert a mechanical force ...
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1answer
40 views

Does an induction cooktop attract or repel the base of a pan?

My first guess would be that the frying pan would be attracted to the induction coil just as any ferrous metal to a solenoid. But I recently found out that an induction coil can actually be designed ...
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Does this setup defy conservation of energy?

Suppose we have two wire loops of the same dimensions placed adjacent to each other. The first loop is connected to an AC source, the medium inside the first loop is air and the medium inside the ...
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41 views

What makes electric field zero in a wire?

Take a ideal inductor (superconductor). Change in magnetic field produces electric field. But in a ideal inductor electric field inside is zero. What makes the electric field zero in a ideal inductor ...
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Electromagnetic induction when both coil and magnet are move simultaneously in opposite directions

Because relative motion between the two is causing current to flow in the coil, would there be any electromagnetic induction in the coil when both coil and magnet move simultaneously in opposite ...
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21 views

How to find the direction of area when calculating an induced e.m.f?

I am trying to solve a problem where there is a straight conductor that is moving on two parallel wire. The magnetic field pointing inwards is time-dependent and so is the position of the conductor. I ...
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Creating a temporary magnet using a simple method

Was just wondering if someone could clarify this situation: When I take a Allen wrench and let it come in contact with an iron nail nothing happens. Not really surprising. None of the objects are ...
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Negative sign in Faraday's Law

With Faraday's law, is it standard convention to leave off the negative sign? Or are answers with negative EMF acceptable (generally speaking)?
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28 views

Can charging by conduction and charging by induction occur simultaneously?

If I connect a neutral body to a charged body (suppose it is negatively charged) with a conducting wire, how will the neutral body get charged - by induction or by conduction?
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Why is the closed line integral of $\oint \mathbf{E}\: d\mathbf{l}$ equal to $-d\Phi/dt$ and not $d\Phi/dt$?

For example, in the case where there is a bar magnet moving through a loop of wire with some resistance, I know that by Lenz's law, the induced emf $\mathcal E$ in the circuit is equal to $-\dfrac{d\...
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Doubt from induced electric field

When a Conducting charged circular loop is placed in a linearly varying magnetic field, will the loop start rotating or current will flow along the loop or both ? Here the plane of the loop is ...
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Mutual Inductance in External Magnetic Field

If I have a transformer in a time dependent magnetic field $B(t)$ (both coils are identical and aligned together, the secondary coil $L_2$ has a load resistance $R$) how would I find the mutual ...
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49 views

What is the problem with infinite current in ideal circuit?

For Some time forget about practical situation. Take an ideal situation. When there is a magnetic field changing in a coil there is electric field induced inside wire. If the wire is perfectly ...
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57 views

Energy conservation in jumping ring experiment

Consider Thomson's jumping ring experiment, where a conducting ring is repelled from a coil after you switched a current in the coil on. The following experiment shows a simplified schematics of the ...
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Position of the electric field induced by a magnetic field

I've been told that a cylindrical time-varying magnetic field induces a non-conservative electric field shaped like circles centred at the axis of the cylindrical magnetic field. I suppose it's an ...
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Electromagnetic Induction Problem

I am getting two different answers from two different methods for this problem, which is to find the potential difference between the points A and B, if the rod is rotated anticlockwise. OAB is a ...
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Electromagentic induction derivation problem

I was learning about proof of Neumann's law on electromagnetic induction. In that proof, they have considered a circular loop carrying current i, a small current element dl and magnetic induction $\...
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Principle of a Generator

In a famous experiment were a conducting rod moves within a uniform magnetic field with a constant velocity perpendicular to the lines of force of the field on two parallel frictionless rails ...
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Clarity in relative motion of magnetic flux

One of the laws of electromagnetic induction goes this way: Whenever relative motion exists between a magnetic field and a closed circuit such that the magnetic flux through that circuit changes, an ...
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Does a time varying magnetic field produce an EMF in an open conducting loop? (slidewire generator example)?

Consider a conducting rod placed in a magnetic field. I understand that if the rod moves normally to the field, it experiences an EMF. Furthermore, if the ends of rod are connected by a wire and the ...
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Why Can't a constant Magnetic Flux Generate Current?

Why is a constant magnetic field able to move individual charges, but must be varying if it is to generate current through a wire of constant area? Isn't current just moving charges? I was thinking ...
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Why does moving a bar magnet through a larger loop of wire generate more current than through a smaller wire at the same speed?

Why does moving a bar magnet through a larger loop of wire generate more current than through a smaller wire at the same speed? A theoretical, rather than rigorously mathematical explanation would ...
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EMF induced in a wire travelling through a loop with B field inside

I got a question like this: a wire is traveling through a loop with a shape as the picture shown, the wire has a constant velocity v, and there is a uniform magnetic field point into the loop. Yet the ...
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According to Lenz’s law, does actual number of turns in a transformer matter, or just turns ratio? If so, why?

I ‘m trying to make a transformer and I understand the basic concept of Lenz’s law, and I understand how the ratios work. I get that if you have a transformer with 100 turns on the primary and 10 on ...
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Faraday's Law Similarities to Ampere's Law

I was wondering if there was any relationship between Faraday's law and Maxwell's addition to ampere's law as both have to do with some sort of time varying flux that generates some sort of current. A ...
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Does plasma beam focus itself at sufficient velocity?

Imagine a beam of positively charged moving particles as shown in first image (the anode is only illustrative): Then take a look at the cross section of such beam in the second image: I imagine that ...

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