Questions tagged [electromagnetic-induction]

This tag is for questions regarding to electromagnetic induction, a process in which a conductor is put in a particular position and magnetic field keeps varying or magnetic field is stationary and a conductor is moving. Electromagnetic Induction was first discovered way back in the 1830’s by Michael Faraday.

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Which of these is the right way to interpret finding the current across a coil

If we have a coil which has a resistance of 100 ohms an induced emf of say 20V and this is connected to an AC power source of 100V and is in a series connection with another resistor of lets say 50 ...
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1 answer
292 views

Potential due to initially uncharged induced conductor?

From Griffiths' Introduction to electrodynamics: In this problem, Griffiths says that we will set the potential inside and on the surface of the conductor to be zero since its an equipotential ...
8 votes
3 answers
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How does a wireless charger work if there is no transfer of electrons?

I have read this: the definition of electrical current is the flow of charge. Now, it is also possible to transfer energy (and therefore power) through either free space or a conductor by ...
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1 answer
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Wrapping a Voltmeter Around a Solenoid

I just read this really interesting paper by Robert H. Romer and it has me curious: what would happen if you wrapped the positive lead of a voltmeter once around a solenoid with a linearly increasing ...
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Why is the Voltage across the coil the difference between the induced emf and the total voltage [closed]

I understand all of this question except for the very end.Its from a test I was looking at from a couple of years ago. A coil consists of 150 turns of wire and has a total resistance of 200 Ohm. It is ...
1 vote
1 answer
226 views

Energy Transformations in a Motor

I'm confused about how the energy transformations in a motor work. I'm not comprehending how the electrical potential energy within the circuit is transformed to rotational kinetic energy of the coil, ...
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0 answers
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Application of Faraday’s law of EMI [closed]

I’m a high school student. In this question the magnetic field is confined to a cylindrical region. I’m assuming that the answer will be same if the magnetic field was not confined. Is my assumption ...
3 votes
1 answer
528 views

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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0 answers
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Self-induction in a permanent magnet

when a permanent magnet is moved in a coil, an emf is induced in the coil. so is an emf also induced in the magnet itself? and if not then why not. and if I replace this permanent magnet with a ...
1 vote
0 answers
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Dirac strings are classically observable through induction?

For my Masterthesis I will have to dive a bit into Dirac monopoles, which are said to be pairwise connected by a Dirac string which is just an infinitesimal fiber carrying magnetic flux $|\vec{B}|=g$. ...
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1 answer
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How eddy currents effect the impedance of source?

When we connect a bigger resistance to a transformer, the current decreases both in the primary and secondary. To be able to maintain the same current, we'd have to increase the voltage. Now imagine ...
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1 answer
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Finding induced magnetic field strength given current.

I'm working on a project involving a Tesla Coil, and I was hoping to figure out how strong an induced magnetic field would be with an input voltage of X. Is there an equation to help solve this? I'm ...
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is my folowing understanding about why induced curent is produced due to a change in magnetic field correct? [closed]

Relativistic Origin of Magnetic Field: the magnetic field is a consequence of relativistic effects acting on the electric field. This implies that changes in the magnetic field will correspond to ...
9 votes
6 answers
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Why does a changing magnetic field produce a current?

A changing magnetic field induces a current in a conductor. For example, if we move a bar magnet near a conductor loop, a current gets induced in it. Faraday's law states that The E.M.F. $\...
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Coilgun efficiency and capacitor banks [closed]

These questions are in context with a coil gun which operates on DC 1). What is the nature of an Inductor in a Direct Current Circuit when connected to a DC capacitor (LC circuit in DC)? 2). How do I ...
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0 answers
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What logic is being used in Bleaney & Bleaney to prove the reciprocity theorem for mutual inductance?

I'm currently reading Bleaney & Bleaney 3rd Ed. On pg 136 they discuss the case of 2 coils. Their logic is as follows: If a second coil is brought near to a coil carrying a current $I_1$, there ...
1 vote
0 answers
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Induced current density and magnetic field arising from forced oscillations of particles in a constant magnetic field?

I am being confused by what should be a simple physical scenario. Let's say I have a small, cylindrical region of radius and height are both $a$ filled with a medium of both positive and negative ...
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2 answers
51 views

Can a finite displacement current density have an associated displacement current of zero?

For an Electric field defined in such a way that $(i)$ it is tangential at every point along a circular path of area $A$, and $(ii)$ has a finite $\frac{\partial E}{\partial t}$ value. Basically it'...
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1 answer
319 views

Electromagnetic induction and magnetic field (conducting rail problem)

Since we know the work done by a magnetic field is zero.now how does the magnetic field changes the kinetic energy of rod when it applies force BIL (where I is current at any instant) moreover if we ...
2 votes
1 answer
1k views

Measurement of electrostatic induction

How is it with the electrostatic induction measurement? Everywhere you can read about the effect of electrostatic induction but I still can't found any detailed explanations or quantitative ...
-1 votes
1 answer
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No displacement current should be produced in this case, but it does!

Considering this question, i think the concept used is wrong coz direction of E produced due to changing magnetic field is along the circular loop(tangential at each point on loop) of radius r. While ...
2 votes
2 answers
179 views

Is the current induced in coil in Faraday's experiment displacement current?

In Faraday's experiment- Only if we have a imaginary coil rather than a real coil, then change of magnetic flux through that imaginary coil and electric field induced in the imaginary coil/region ...
0 votes
3 answers
996 views

Faraday's law and motional EMF

My understanding of motional EMF is that one of the ways it is created is by moving a conductor (moving such that its orientation doesn't change) in a uniform magnetic field (non changing). EMF is ...
6 votes
4 answers
701 views

How do Electric and magnetic fields generate each other (mathematically)?

Regarding electromagnetism, a changing magnetic flux$(\phi_B)$ produces emf by-$$EMF= -\frac{d \phi_B}{dt}\tag1$$ This emf creates a current which again creates a magnetic field given by-(bio-savart ...
2 votes
2 answers
697 views

What factors does magnetic field due to a circular loop depend on?

I know of three. Strength of current number of loops ( a cheeky way to 'increase' current?) radius I'm having doubts about radius of circular loop affecting the magnitude of magnetic field ta ...
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1 answer
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Induced Electric field due to magnetic field in Faraday experiment

Regarding this experiment where a magnet is moved in and out of a coil -(see the picture) what i considered to be true is that when there is a changing magnetic flux through the coil(due to changing ...
0 votes
1 answer
340 views

Cause of induced EMF in a loop

Len'z law states that the change of magnetic field in a loop of wire produced current in a wire as the magnetic field in and out the loop.Although it just true experimentally, but i) What happened ...
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3 answers
339 views

Amount of energy that can be stored from Faraday flashlight / linear alternator?

You'll have to forgive me if this question is either extremely elementary or does not make sense — I am a civil engineer with little E/M physics background beyond high school education. I am working ...
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1 answer
708 views

Which surface to use in Faraday's law?

To find the emf (voltage) generated for a changing magnetic field around a conducting loop, we use faraday's law with flux defined across the surface of the disk which the loop encloses. This tells ...
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1 answer
714 views

Finding direction of induced EMF

How should I find out the direction of the EMF induced in a rod of any length $l$ rotating with an angular speed $w$ in a region of magnetic field (perpendicular to the plane of the rotating rod) ...
0 votes
3 answers
65 views

Are there losses in an ideal transformer?

In a circuit with an AV power source $V$ and a zero-resistance ideal coil, the power from the source. $P_{in} = IV$ is equal to the rate of change in the magnetic energy $U_B$ stored in the coil. The ...
1 vote
2 answers
325 views

How is the direction of current induced by the induced magnetic field determined in a metal detector?

In the figure below, from a textbook explaining Eddy Currents, a pulse of current is sent and generates a magnetic field $ B_0 $. The magnetic field produces a change in flux in the metal box that ...
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0 answers
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I can’t figure out the magnetic field around a non-straight wire

Say I have a circuit where the wire has a shape defined by some closed Parametric defined as $(X(t), Y(t), Z(t))$ (it is a loop), how do I calculate the entire magnetic field around the circuit?
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1 answer
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What is the difference between the induction of a magnetic field $B$ and the magnetic field strength $H$?

I just started learning about magnetic fields by myself. In my textbook it says that the magnitude or intensity of induction of a magnetic field is equal to the amount of field lines that pass through ...
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2 answers
225 views

In a transformer, why does $V_p$ depend on the flux?

To obtain the emf in the secondary of a transformer as a function of $V_p$ (input voltage in the primary), we asume that $V_s=N_s\frac{d\phi}{dt}$ and that $V_p=N_p\frac{d\phi}{dt}$. What I don't ...
0 votes
2 answers
39 views

Magnetization current when two magnets are brought together and the Lorentz force law

Suppose we have two ferromagnetic objects constituting two permanent magnets. A classical way to think of the two magnets repelling/attracting each other would be by ascribing bulk and surface ...
1 vote
2 answers
81 views

Did my pot really reach >400°C internally while heating water (soup broth)

I have a 1800W induction cooktop. In my experiment, did the following steps: I placed a stainless pot on the cooktop, half filled with fridge cold chicken broth. I heated the pot at 1000W until I ...
1 vote
1 answer
215 views

Does the electric field ($E$ caused by induction) of a moving conductor in a magnetic field drop when connected to a curcuit?

We know that when a conductor moves in a homogenous magnetic field that is perpendicular to itself due to the amount of electric charge gathered on one end of the conductor( as a result of the lorentz ...
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2 answers
393 views

Why is the flux not zero here (Faraday's law)?

I've recently been reading the Griffiths Electrodynamics book, and came across this problem (7.17, 4th edition) and its solution: I don't have any objections for the solution to part a). I have, ...
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Will a charged body generate current in this situation?

Suppose we charge a body with negative charge. We then place it inside a Faraday shield that has openings in the form of vertical slits. A coil surrounds the shield. If we start rotating the Faraday ...
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2 answers
300 views

Should a wire loop moving through a constant rectangular magnetic field directed perpendicular to it's motion have zero induced current in the middle?

Suppose we have a loop of copper wire moving perpendicularly through a constant finite rectangular magnetic field directed into the screen . When the loop enters the field, the induced current would ...
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0 answers
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Is AC voltage across transformer pi shifted?

Suppose the voltage in the primary coil in a capacitor be Vprimary = Vosin(wt) According to my understanding, as the (AC) current in the circuit increases, the Magnetic flux across the secondary ...
0 votes
1 answer
362 views

Back emf in an Inductor with an A.C supply

If a pure inductor is supplied with an AC voltage we will always have AC current and time changing electric field in the circuit. That always changing electricfield will cause changing magnetic field ...
1 vote
1 answer
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Application of Faraday's law to a wire inside a coaxial cylinder with alternating current

I'm having some trouble solving an electrodynamics problem. There is a wire inside a coaxial cylindrical conductor of radius $a$. An alternating current $I=I_0 cos(\omega t)$ flows in the wire and ...
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2 answers
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Inducing electric field vs Inducing magnetic field

Is it easier to induce an electric field using a changing magnetic field or the other way around? The question is from my high school booklet, and I am pretty sure it was to be answered on an ...
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0 answers
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Eletrostatic induction

I know that when we are dealing with a charge inside a, initially neutral, spherical conductor, the outside induced charge will rearrange uniformly. But, let's say now we have two conductive planes, ...
0 votes
1 answer
556 views

Location of high and low potential points in motional emf

Okay so in the above image the semi circular loop is rotated and a sector of it is introduced into the magnetic field. Questions: I know the magnetic field is constant so no non conservative ...
0 votes
1 answer
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The effect of the inner diameter of a tube on the speed of a magnet falling through it

I have done the experiment of dropping permanent magnets through copper tubes and observing how they fall slower. With a tube that has an inner diameter close to the permanent magnet (a tight fit) the ...
0 votes
1 answer
518 views

Lenz law - Direction of induced current

I understand the Lenz Law is such that it tells us that the induced current must be in a direction that makes the end of the solenoid facing the magnet behave as a North Pole to repel the magnet’s ...

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