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
1 answer
20 views

Can ionized air be used as a conductive medium for eddy brakes?

Sort of a conceptual engineering question, apologies if I am missing something, my background is in mechanical engr. Essentially, I was inspired by the classic experiment of dropping a magnet in a ...
0 votes
0 answers
18 views

AC electromagnetic waves: interference and sensing technologies

When measuring the magnetic flux density around a current carrying wire it is possible to use a coil (with a ferrite for greater concentrations). These coils are "directionally sensitive" (...
0 votes
1 answer
10 views

Does a constant magnetic field induce an emf in space irrespective of what is inside the space?

I came across a question which was a pyq from an Indian examination.The question states; An insulting rod of length L is falling with a velocity v perpendicular to B as well as perpendicular to L. ...
  • 1
2 votes
4 answers
62 views

Inductor connected to an AC source

Consider an inductor connected to an AC source, $V=V_0\sin\omega t$. Let the the switch in the circuit be closed at $t=0$. Then by Kirchoff's voltage law, $$ V-L\frac{dI}{dt}=0 $$ where $I$ is the ...
  • 23
1 vote
1 answer
28 views

Intuition of Faraday's law at a boundary

I know that Faraday's law means that the tangential electric fields have to be equal at both sides of a boundary. I'm struggling to understand intuitively why this has to be the case. What would ...
  • 11
0 votes
1 answer
22 views

What effects do inductors have on circuits?

The above diagram is a simple circuit containing an inductor. According to the right hand grip rule, it can be deduced that the magnetic field is to the right. But the magnetic field produced by the ...
0 votes
2 answers
56 views

What type of electric field is created by time varying magnetic field?

Example when an current carrying loop is placed in external magnetic field varying with time some emf is produced in the coil now we know that emf is due to electric field and the loop is experiencing ...
0 votes
4 answers
59 views

Why $di/dt$ in inductor circuit reduces gradually after closing the switch?

When we close circuit having an inductor, an induced emf is generated across the inductor which opposes change in current through the circuit. This back emf depends on rate of change of current $di/dt$...
0 votes
1 answer
27 views

Induced emf without flux change

In the picture below, the rectangular coil of wire is moving out of the page, so that only its upper part lies within the magnetic field. This movement creates motional emf in the upper side of the ...
1 vote
2 answers
39 views

Doubling the length of a solenoid doubles its inductance. Two identical solenoids in series have up to four times the inductance due to M. Why?

The inductance of a long solenoid with $N_o$ turns and a length $l_o$ is $$L_o=\pi r^2 \mu_0\frac{N_o^2}{l_o}$$ If I now make a new solenoid, $L_{new}$, with double the length of the original ($l_{new}...
  • 1,401
3 votes
2 answers
264 views

Why does a changing magnetic flux induce an EMF in "opposite direction"?

Faraday's Law of Induction tells us that a changing magnetic flux induces an EMF in the conductor, causing an electric current to flow. By Lenz's Law, we get the direction of induced EMF which turns ...
0 votes
2 answers
70 views

Can you use electrical appliances inside a Faraday's Cage?

I have read that if a charge was to be placed inside the cavity of a Faraday's Cage, its electric field would be canceled by the field applied by the interior surface of the cage's conducting material,...
0 votes
1 answer
35 views

Am I misunderstanding the concept of magnetic flux?

I have encountered a problem which I should know how to solve because I have studied electromagnetism and did a wide range of problems, but there is something conceptual that is keeping me from ...
  • 7
-1 votes
1 answer
110 views

Doubt regarding the calculation of EMF due to self-inductance and mutual inductance

When finding the EMF induced in an inductor due to both self-inductance and mutual inductance, the EMFs due to both of these contributions are summed. However, I have doubts regarding their summation. ...
  • 43
1 vote
0 answers
16 views

Non-parallel magnetic dipole falling throug copper tube

What happens with magnetic dipole while falling through copper cylinder? If it's parallel to z-axis (shown on picture below with red color) we know that it stays parallel to the z-axis all the way ...
0 votes
1 answer
16 views

Force components on dipole falling through copper ring

We have a magentic dipole parallel with z-axis (shown on the diagram below) falling through copper loop, because of changing magnetic flux there is induced current in cooper ring/loop and consequently ...
1 vote
1 answer
19 views

Why is the flux linkage of one coil with respect to the other always equal if they are coaxial

M12 = M21= M (say) (6.14) We have demonstrated this equality for long co-axial solenoids. However, the relationship is far more general. Note that if the inner solenoid was much shorter than (and ...
  • 119
0 votes
0 answers
24 views

Magnet falling in copper tube, radial force component

Consider a Dipole magnet falling through infinite copper pipe. If we displace a magnet a little bit so that the dipole isn't pointing to the same way as pipe (dipole isn't parallel to the pipe) we get ...
1 vote
1 answer
90 views

Magnetic force is a no work force. Why is it doing work here?

Here the rod is projected with a velocity $v_0$ . Due to change in flux in the loop, we have an induced emf in the loop, which induces a current $i$ that exerts a force $Bil$ where $B$ is the magnetic ...
1 vote
0 answers
24 views

Inductance in case of volume and surface currents [closed]

Is inductance always just defined as the constant relating flux directly to current? Is it true even for surface and volume currents?
0 votes
2 answers
68 views

Does the EMF induced in an inductor due to mutual inductance equal the total EMF?

For an inductor in a circuit without a power source, does the induced emf found by using the mutual inductance value include self inductance, or is the self induced emf considered separately? From ...
  • 43
1 vote
0 answers
26 views

Aluminium foil sticks to steel ring in Ring Launcher

In this video (timestamp included in link) a very strange phenomenon is demonstrated. The aluminium foil layer initially shows no reaction to the alternating magnetic field, but as soon as the thick ...
0 votes
0 answers
14 views

Do eddy currents flow through the depth of sheets of conductors?

For a physics experiment (IB EE) I plan to investigate the motion of a magnetic pendulum across sheets of conductors, aluminum sheets.I know that a thicker block of aluminum for example would create ...
  • 21
1 vote
1 answer
33 views

Emf induced by a solenoid

Could someone please clear my confusion regarding this concept and point out what is wrong with my argument: Say we have a simple circuit as shown in the image: Why is the potential difference ...
's user avatar
0 votes
1 answer
48 views

Motion of a conducting loop in a time-dependent external magnetic field

The problem statement: "A conducting ring of radius 'r' is held stationary in a magnetic field $\vec{B}$ which, initially has a magnitude of $B_0$ and is inclined at $45^\text{o}$ to the area ...
  • 89
0 votes
0 answers
37 views

Why is there an EMF induced across a ring falling in a magnetic field in a manner such that the area vector is parallel to it?

I had an exam today, wherein an object was falling via a magnetic field such that the area vector was parallel to the field (uniform), the question was is an EMF induced, my answer was no,as the ...
  • 119
0 votes
0 answers
26 views

Understanding the interaction of two inductors, e.g mutual inductance, transformers, without energy conservation

Is there a way to understand the interaction of two inductors, such as in transformers and in mutual induction, without using energy conservation? In the texts that I have read so far, whenever I have ...
  • 43
0 votes
0 answers
23 views

Electrons under effect of induced electric field

Suppose a magnetic field exists in a region $0<r<a$ and a circular wire loop (conductor) is placed around it such that its radius is more than $a$. If the rate of increase of flux is ...
0 votes
1 answer
28 views

How to find the electric field in a inductor? [closed]

There's a problem that I didn't understand when I was at school, and it's still unclear. Suppose a simple circuit, an AC constant current source $I=I_{0}\exp(j\omega t)$ the current is, and an ...
0 votes
1 answer
25 views

Does induced current lag induced emf in mutual induction?

In a circuit with an alternating emf source, resistor and inductor, the current lags the induced emf on the inductor because the inductor initially opposes a change in current. Now, consider a circuit ...
  • 43
2 votes
3 answers
546 views

Closed loop integral of Electric Field dotted with dL

I am struggling to wrap my head around Faraday's law: $$\oint\mathbf{E}\cdot d\mathbf{l} =-\frac{d\Phi}{dt} = -\frac{d}{dt}\int_S\mathbf{B}\cdot d\mathbf{S}$$ Integral of an Electric field dotted ...
0 votes
0 answers
146 views

Why does this derivation not work for showing $M_{12}= M_{21}$ for mutual inductance?

If we assume two inductors behave like the centers of ideal solenoids then the induced emf in inductor 2 due to inductor 1 will be found by $-N_2 \frac{d \phi_{21}}{dt}$. But the induced emf is also ...
  • 43
0 votes
1 answer
22 views

Does the direction of the change in magnetic flux matter in Lenz's law?

Does the direction of the change in magnetic flux matter ? For instance, here, the change in flux(taking downwards to be positive) is positive if the magnetic is falling with its north-pole facing ...
  • 119
0 votes
2 answers
58 views

Self-Inductance of a coil: What is the logical reason to not just write $\Phi = L * I$ but we also add the factor $N$ to the left side?

What is the reason to not just write $\Phi = L\cdot I$ but we also add the factor $N$ to the left side? ($N\cdot\Phi = L\cdot I$) $\Phi$ is in Webers here, and is the induced magnetic flux. $L$ is the ...
0 votes
0 answers
21 views

Is it better to spread the coil to maximize magnetic strength in air gap of a C shape iron core

See the 2 example below of a C shape Iron Core 99.8% iron. in both cases, assume that: the wire length is the same, say 1000 feet of copper wire. The amp being used is the same The N turns are the ...
0 votes
0 answers
22 views

How to calculate Tesla value at the end of a solenoid when iron surface expands?

assumptions: The core and top cylinder are made of pure iron 99.8% with a permeability ( µ ). To calculate the Tesla value at point B (at then end of the solenoid), we use: $$B =\frac{\mu\cdot N\cdot ...
1 vote
0 answers
20 views

Finding the geometry of induced electric fields using Faraday's law

Thinking of a long straight wire carrying increasing or decreasing current, we know by using Faraday's law of induction that the magnetic field produced by this wire will induce an electric field. Now,...
  • 43
1 vote
2 answers
29 views

Why dont magnetic fields made by a wire impede the current within said wire after the magnetic fields are made?

In an inductor why dont the magnetic fields impede current after the magnetic fields are fully created? Because it seems counter intuitive that they wouldnt make it really hard for current to flow. ...
0 votes
1 answer
37 views

Understanding the symmetry argument in determining induced electric fields

I am trying to understand how to determine the shape and direction of the electric fields induced by a changing magnetic field. But all of the resources I have read make use of the following symmetry ...
  • 43
0 votes
0 answers
42 views

Satisfying and puzzling phenomenon about magnetic dipole

I just found a cool video of magnet falling through cooper pipe. So I naturally have a couple of questions about this physics phenomenon. I even tried to derive the equations of motion... During my ...
6 votes
3 answers
1k views

Suspicious EMF equation

Some context: I am trying to get the equation of motion for a dipole magnet falling through copper pipe. To proceed I need to calculate the EMF. We can do this by using Faraday's law, $$\oint_{\...
2 votes
1 answer
146 views

How are people with orthopedic implants made from titanium and platinum not detected by metal detectors?

According to my understanding, the magnetic field created by the metal detector is inducing eddy currents through a nearby metal, then that eddy current creates its own magnetic field which can be ...
  • 459
0 votes
1 answer
41 views

Motional emf of two sliders

There are two sliders and they can slide on two frictionless parallel wires in uniform magnetic field B, which is present everywhere. The mass of each slider is m, resistance R and initially, these ...
0 votes
0 answers
21 views

Electromagnet attracting permanent magnet?

Permanent magnet gets attracted to electromagnets iron core ,but if we energize electromagnet for attraction force will it attract strongly?
1 vote
1 answer
39 views

If we apply a magnetic field to a core saturated by a permanent magnet, what will happen? [closed]

If we apply a magnetic field to a core saturated by permanent magnet, will the magnetic field of the permanent magnet and electromagnet get combined? I mean to say superposition will be applied?
0 votes
2 answers
33 views

Difference between electromotive force and back electromotive force

I'm wondering what is the difference between electromotive force EMG and back electromotive force BEMG. I tried to answer in the following way by using two examples. but I'm not sure about the ...
0 votes
0 answers
18 views

Faraday's Law of Induction and charge rearrangement

Suppose you have a coil placed in a time-varying non-uniform magnetic field. I would like to emphasize the non-uniformity of the magnetic field being significant i.e. it varies notably over the ...
1 vote
0 answers
43 views

Square coil circuit and variable magnetic field problem

I am attempting to solve the following problem. A square coil of side $l = 40.6 \ cm$ and resistor $R = 95.5 \ \Omega$ is contained within the $xy$ plane. Within the same region a magnetic field, ...
0 votes
1 answer
50 views

Have there been any experiments in which the Earth's electromagnetic field was used to do work?

Simply speaking using faraday's law to generate electricity with the use of earth's magnetic field. I'm not talking about some revolutionary new way of generating electricity that would end our energy ...
  • 111
0 votes
1 answer
122 views

What is the fundamental explanation for electromagnetic induction from the relativistic point of view?

Background Faraday's law of induction gives a quantitive formula for the induced emf in a loop with changing magnetic influx through it: $$\epsilon =-\frac{d\Phi_B}{dt}$$ Although this law is entirely ...
  • 389

1
2 3 4 5
25