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.

Filter by
Sorted by
Tagged with
0 votes
0 answers
11 views

How to reduce magnetic field between two magnetic shield sheets?

I put 2 parallel silicon steel sheets between magnetic field as below: As silicon steel has much bigger permeability than air,magnetic line will go through 2 silicon steel sheets. What I can do to ...
user avatar
  • 111
0 votes
0 answers
10 views

Decay time of rotational frequency of the ring

This is a question for one of my exams. I have uploaded my way of solving below. I have some queries: (i) The time I derived is independent of minor radius a but by commonsense, I know with the ...
user avatar
  • 11
0 votes
0 answers
28 views

Current in primary circuit when diode in secondary circuit is reverse biased

Let's say we have an ideal transformer with a diode in the secondary circuit: If the diode is reverse biased, there would be no current in the secondary circuit, which would mean that there is no ...
user avatar
  • 3
0 votes
1 answer
50 views

Magnetic potential $\vec A$ and induction $\vec B$ [closed]

The vector potential $\vec A$ of a magnetic dipole, dipole moment $\vec m$, is given by $\vec A(\vec r) = k [ \vec m \times \vec r]$,where $k = \mu_0/4\pi r^3$. The magnetic induction $\vec B = \...
user avatar
  • 119
0 votes
2 answers
18 views

What is the difference between the self-inductance of a branch and self-inductance of a loop in lumped circuit models?

When we talk about lumped circuit model, I get confused about the terminology that is generally used. For a loop, we do know that the total flux through the loop can be written as $\Phi = \Phi_{ext} + ...
user avatar
  • 970
1 vote
0 answers
32 views

Modeling the Effect of Magnetic Induction on Single Neurons

In this paper, the authors suggest a potential mechanism for magnetoreception in birds: as the Earth's magnetic field (taken to be homogeneous over sufficiently small spatial scales) passes through ...
user avatar
  • 339
0 votes
0 answers
18 views

Confusion about Lenz's law and change in magnetic flux

I'm not sure this type of question belongs on SE as it may seem more hw-e type, so please comment if it is not and I'll remove it For this problem, in particular b) where it asks "During the ...
user avatar
  • 83
0 votes
1 answer
32 views

Would a ring magnet around a copper tube be slowed?

if a ring-shaped magnet was dropped with a copper pole through the center would it be slowed the same as a cylindrical magnet in a copper tube? if so would it be slowed more or less?
user avatar
0 votes
3 answers
44 views

Direction of current from electromagnetic induction

I've only scratched the surface of electromagnetism but I figured I might as well ask a question. When moving a permanent magnet relative to an electric conductor, a current will form. Say you just ...
user avatar
0 votes
1 answer
33 views

Can the induced voltage in an inductor coil reverse the direction of curent?

This doubt arose when I was thinking of the following simple case. I have an inductor coil of resistance $1\ \Omega$ and self inductance $0.5 \text{ H}$, this is connected to a variable voltage supply ...
user avatar
0 votes
0 answers
35 views

Working principle of the five(5) needle telegraph by Cooke and WheatStone

So I’m studying the history of telecommunications and came across the five (5) needle telegraph by Cooke and WheatStone. I want to replicate it but can’t get a grasp on the working principles. In a ...
user avatar
0 votes
1 answer
26 views

Magnetic flux through a closed surface

I was reading Electromagnetic Induction, then I faced a understanding problem while reading the integral and differential form of Faraday's Law.. We know Magnetic Flux= ${\bf B} \cdot {\bf S}$ Where ${...
user avatar
0 votes
0 answers
25 views

Effect of varying length of solenoid coil on magnetic flux

Given the number of turns (N) and current is constant for any cross section of the coil, does varying the length of the coil not have any effect on the magnetic flux in the centre of the coil? i.e. a ...
user avatar
0 votes
1 answer
16 views

Heating of conductor due to induction?

When I move a charge back and forth from a conductor not touching the conductor, will flow of electron generate heat also? Back and forth, as conductor is mean position for SHM of charge.
user avatar
  • 19
0 votes
1 answer
36 views

Bar magnet dropped through wire loop

I was wondering how an emf versus time graph for this situation will change if the distance from which the bar magnet is released decreases? Many thanks
user avatar
0 votes
2 answers
40 views

Is Farady's law valid for conducting loop only? [duplicate]

Is it applicable to a nonconductive loop? What if the loop consists of both non-conducting and conducting paths?
user avatar
  • 424
0 votes
0 answers
10 views

Magnetic flux from maximum induced emf as a function of angular velocity?

I've done an experiment where I have a small rotating coil in a uniform magnetic field and I've measured the induced emf in the rotating coil as a function of time for several different angular ...
user avatar
0 votes
0 answers
19 views

Eddy Currents Confusion

Here is an image of the classic aluminium vane damping setup in which the induced eddy currents oppose the rate of change of flux. That's all intuitive. The confusion I have is why the force caused by ...
user avatar
  • 381
0 votes
3 answers
42 views

Inductance in AC circuit

Why does an inductor oppose a change in current and not voltage? Is it a rule or is it because of lenz's law? Because intuitively the back e.m.f which opposes a change in current should also oppose a ...
user avatar
  • 97
0 votes
1 answer
25 views

Why does decreasing the magnetic flux through a loop of wire result in an increase in EMF in the loop?

The general formula to calculate the EMF in a loop of wire due to a change in magnetic flux is: ε = - (ΔΦB /Δt) This means that as the magnetic flux through a loop of wire (which is often the result ...
user avatar
0 votes
0 answers
26 views

Does the magnitude of the induced current change?

The coil is circular and is closed, meaning that current can flow through it. So this enters a region of magnetic field where with time, more and more magnetic field lines cross it. My question is, ...
user avatar
0 votes
0 answers
37 views

What exactly are relativistic fields?

Is magnetic field relativistic? Is electric field relativistic? How do you imagine something causing an actual physical difference to be purely dependent on the choice of a reference frame?
user avatar
0 votes
1 answer
33 views

Why is the equation of the induced current in the secondary coil in a transformer true? [closed]

According to introductory physics books, the induced voltage in the primary coil due to self-inductance = the emf of the voltage source= N1*(change in magnetic flux/time). I find this statement wrong ...
user avatar
  • 9
-1 votes
2 answers
82 views

How long of a wire do i need to construct a solenoid of $N$ turns? [closed]

Consider an MRI scanner with a hole diameter of $60 ~ cm$ and producing a field of $B_{0} = 1.5 ~ T$ and has a length of $50 ~ cm$. Furthermore, let us assume that the remanence of a permanent magnet ...
user avatar
  • 3
-2 votes
1 answer
28 views

EMF Induced in a portion of a Loop by time varying Magnetic Field [closed]

Here I understand that they are asking about the EMF Induced in the Portion AOB. I do know how to calculate the Induced EMF for the whole Circular Loop, but for shape like this, I am struggling a ...
user avatar
  • 21
0 votes
1 answer
30 views

Faraday's law - direction of non-conservative electric field

I would like to conduct the following experiment. I place charged particle above the wire and increase current in the wire. I expect particle to move, but not sure of the direction of the movement. ...
user avatar
4 votes
1 answer
214 views

Why can voltages be summed around a circuit if there is magnetic induction?

So there is this class I'm attending on Electronic Instrumentation which involves mostly circuit analysis. For example, RCL circuits, and circuits that also contain opamps, transistors, diodes, etc. ...
user avatar
  • 105
0 votes
1 answer
17 views

EMF Induced in a Conductor Rotating in A Field

Can you help me visualize and understand this question as to why the answer is A? I know that the field lines should cut through and sin of the angle between the magnetic field and the motion of the ...
user avatar
  • 47
0 votes
0 answers
27 views

Window $H$-field in transformer

In the paper Power flow in transformers via the Poynting vector by J. Edwards and Tapan Kumar Saha, there appears an illustration of the electromagnetic fields in a transformer. When the primary of a ...
user avatar
1 vote
2 answers
44 views

Is induced emf primarily produced (only) at the cost of mechanical energy?

A few days ago we had a physics test which included the following multiple choice question:- Induced emf is primarily produced at the expense of________. a)Electrical Energy; (b)Mechanical energy ...
user avatar
0 votes
1 answer
39 views

Electron in varying magnetic field

Lets consider an electron that is placed in an existing, constant in space near the electron, magnetic field. Electron is stationary. Magnetic field over time gradually reduces to zero. I assume ...
user avatar
0 votes
2 answers
43 views

Faraday's law with a battery

So I've recently learned about Faraday's law of induction and I'm still confused about a particular situation. Suppose there is an electric circuit: a circular loop of radius $r$ composing of a ...
user avatar
0 votes
1 answer
38 views

Induced voltage from magnetic field

Suppose we have a surface S(x,y) = x^2-2y for 0<x<2,0<y<5 , and a magnetic field (2t,3t+1,t). To find the total magnetic flux through the surface S we find a normal vector to S n = (-Sx,-...
user avatar
1 vote
1 answer
25 views

Find the work to move a coil in an uniform magnetic field [closed]

we have a rectangular coil ($d$ and $3d$ wide) in a magnetic field as in the picture. To the left we have $B_0 T$ and to the right $\frac{B_0}{2} T$. There is a counterclockwise current in the coil ...
user avatar
3 votes
2 answers
385 views

What does the surface integral tell us, and how is it different from surface area?

In the context of Faraday's Law of Induction, Will a paraboloid with the same cross sectional area as a major portion of the sphere (Spherical Cap), have the same magnetic flux, when put in an uniform ...
user avatar
0 votes
1 answer
22 views

Magnetic flux and the charge passing through a wire

Faraday's Law we have $$\mathcal{E}= -N\frac{\partial \Phi}{\partial t}.$$ Assuming the flux only depends on time and can be expressed as $\Phi = \Phi (t)$, the aforesaid formula can be re-written as: ...
user avatar
4 votes
2 answers
87 views

Fundamental, intuitive interpretation of the magnetic field $\vec{H}$

In many electrodynamics/magnetism textbooks it is stated that the magnetic induction $\vec{B}$ is related to the magnetic field $\vec{H}$ via $\vec{B}=\mu_0(\vec{H}+\vec{M})$. It is then argued that $\...
user avatar
  • 842
0 votes
2 answers
44 views

Why is mechanical work equal to Joule heating?

This question came about when I was doing a problem related to a conducting loop with resistance $R$ moving with velocity $v$ in a magnetic field. It asks you to verify an expression for the force ...
user avatar
  • 215
0 votes
1 answer
37 views

Why wire grid polarizers do not re emit absorbed radiation both ways?

The wikipedia page on polarizers states about wire grid polarizers that : "Electromagnetic waves that have a component of their electric fields aligned parallel to the wires will induce the ...
user avatar
0 votes
1 answer
51 views

Induced e.m.f and the speed of the magnet. (A-Levels Physics)

When a magnet is moved into a coil of $50$ turns at $0.12$ m/s, an E.M.F. of $3.60$ V is generated into the coil. What will be the E.M.F. generated when the magnet is removed from the coil at $0.48$ m/...
user avatar
0 votes
2 answers
56 views

Does the induced EMF depend on the rate if change in the total flux affecting the coil or the external flux only?

If we get a coil which is put in a changing magnetic field that increases at a constant rate, then it is known that this increase in magnetic field induces an EMF, now if the circuit is closed then ...
user avatar
2 votes
1 answer
29 views

Find the inductance of the coil by potential difference of the circuit [closed]

A coil is connected in series with a 10.0 k$\Omega$ resistor. An ideal 50.0 V battery is applied across the two devices, and the current reaches a value of 2.00 mA after 5.00 ms. Find the inductance ...
user avatar
0 votes
1 answer
39 views

For Eddy Currents, must the conductor be large in area size?

Consider the following classical configuration: Let's change a few things, lets assume that: There is no applied current on the wire & it's stationary. The external magnetic field was from a ...
user avatar
  • 627
0 votes
0 answers
31 views

Induced current by a rotating magnetic dipole in a loop

I am trying to compute the current $I(t)$ induced by a rotating magnetic dipole having magnetic moment $\vec{m}$ in a conducting loop of resistance $R$ and radius $r$. The magnetic dipole is placed at ...
user avatar
  • 432
0 votes
1 answer
50 views

Confusion regarding conservation and conversion of energy in Lenz's law

My book states that: In Lenz's Law, mechanical energy of the magnet gets converted to electrical energy, hence Law of Conservation of Energy is maintained. But Faraday's Law tells that if relative ...
user avatar
1 vote
1 answer
63 views

Heuristic expressions for the inductance of a finite-length solenoid

The expression for the inductance of a very long solenoid is $$L = \frac{\mu_0 N^2(\pi r^2)}{l}$$ where $l$, $r$ and $N$ are the length, radius and number of turns respectively. Things get much ...
user avatar
  • 1,110
0 votes
1 answer
37 views

How to find the force needed? [closed]

To keep the system in equilibrium, the Fg should equal FBuoyant + FMagnetic. However, I'm having trouble seeing how the FMagnetic would push the tube upwards. We're using conventional current, and the ...
user avatar
1 vote
3 answers
56 views

Nature of force between two permanent magnets

When we put two permanent magnets close to each other they repel or attract each other and this process increase their kinetic energy. I know that magnetic force can't increase kinetic energy so plz ...
user avatar
2 votes
2 answers
67 views

Why does the north pole of a magnet always induce a south pole in the near end of a magnetic material?

If a magnetic material such as an iron bar is placed near a magnet, the former becomes an induced magnet with the end closest to the north pole of the magnet becoming a south pole and vice-versa for ...
user avatar
  • 381
0 votes
1 answer
27 views

Faraday‘s law of induction integral form

If we want to derive the integral form of Faraday‘s law of induction from $$\nabla \times \vec{E}=-\frac{\partial \vec{B}}{\partial t} $$ we get with Stokes: $$\int_{\partial A}(\vec{E}+\vec{v}\times\...
user avatar
  • 349

1
2 3 4 5
30