Electromagnetic induction Definition and 56 Discussions
Electromagnetic or magnetic induction is the production of an electromotive force across an electrical conductor in a changing magnetic field.
Michael Faraday is generally credited with the discovery of induction in 1831, and James Clerk Maxwell mathematically described it as Faraday's law of induction. Lenz's law describes the direction of the induced field. Faraday's law was later generalized to become the Maxwell–Faraday equation, one of the four Maxwell equations in his theory of electromagnetism.
Electromagnetic induction has found many applications, including electrical components such as inductors and transformers, and devices such as electric motors and generators.
As a project, I am demonstrating electromagnetic induction by making an AC generator. The magnets I currently have access to are very strong neodymimium countersunk magnets, but I noticed that they utilise a Halbach array. I am aware that this means the magnet has alternating N-S poles spaced...
This question appeared in a university entrance exam.Basically, if magnetic flux passing through a surface of a loop changes over time ,only then e.m.f will be induced to that loop.But here only a straight line is used and there's no chance of forming any area.So by definition there's no chance...
I am having problems understanding point (b) so I would like to know if my reasoning in that part is correct and/or how to think about that part because I don't see how to justify the assumption ##v_y=0\ m/s##. Thanks.
I set up the ##xyz## coordinates system in the usual way with ##xy## in the...
Looking at how the induced EMF is proportional to the rate of change of magnetic flux, intuitively it seems that if I increase the velocity of the magnet through the solenoid, i.e. drop it from a higher height, the EMF should increase as well. However, I am unsure if this is true and can't seem...
The flux enclosed by the loop consisting of the solenoid, wires and conducting rod at an angle θ is Φ = blBsinθ, then using small angle approximations and differentiating the induced emf can be found.
I know that there must be some torque opposing the motion but am unsure how to proceed.
hi guys
one of my friends asked me about the origin of the electromagnetic induction, I know somehow that its related to the Lorenz force as the electrons in the conduction band of say the coil interact with the magnetic field ,which results in separation of electrons and positive ions which...
When you try to create time varying magnetic fields in solid metals, there is severe heating due to eddy currents, when you increase the frequency, just like in NDT(non destructive testing) the magnetic field is pushed away from the core to the periphery due to eddy currents opposing the field...
Imagine a magnet moving up and down so that its flux 'B' cuts the copper rod to produce an alternating emf, suppose if the movement is fast enough such that its frequency equals to the electron spin resonance frequency given by F = B x 2.8 Mhz per gauss, neglecting skin effect, more copper...
On examining Maxwell's third equation which is about time varying magnetic fields (Faraday's electromagnetic induction) we find that time varying magnetic fields produce loops of electric fields in space irrespective of whether a coil is present or not, if any coil is present then these loops of...
I would like to ask a question about the induced voltage of an AC generator. So, according to a graph I found on Google, the maximum induced voltage is reached when the loop is parallel to the loop. (The graph shown below.)
Then I was wondering, what if the loop is initially (when it is at 0...
Faraday first demonstrated his law of induction by showing that when he created a current in one wire coil it created a second current in a second coil.
Another experiment showed the same effect. When he moved a magnet through a wire coil, it created a current in the coil.
My question is this...
In electromagnetic radiation, the electric field and the magnetic field mutually induce each other: but my impression is that it would be better to say that they are two aspects of the same wave, so that there is no time between them. However, an alternative would be that there would be that...
A square conducting loop of side length a is in a non-uniform magnetic field. The loop occupies the first quadrant of the xy plane, i.e. the space between the origin (x, y) = (0,0) and the point (x,y) = (a, a). The magnetic field is in the +z direction. Develop an expression for the magnitude of...
This question is motivated by Problem 7.12 in Griffiths Electrodynamics book. I have not included it in the homework section, because I have already solved it correctly. However, I question whether my solution which agrees with the solution's manual is correct.
Relevant Equations:
$$\Phi =...
I first calculated Magnetic field at a distance x using Ampere's law.Then i took an element and wrote its inductance using L=Flux/Current.
Then i integrated from a to b.
But i arrived at nothing.
Help.
In order to calculate for the curl of the induced electric field for a loop moving in a uniform magnetic field, and using the cylindrical coordinate system for a curl, it's my understanding that since the B field is in the 𝑧̂ direction, then so is the partial time derivative of B, and therefore...
Above is an example figure.
2. When a ring in a changing magnetic field is not complete (i.e. open circuit with a small gap), how to analyze the emf of the ring?
According to the general form of Faraday's law, ## \oint \vec{E} \cdot d \vec{s} = -\frac{d \Phi}{dt} ##, I deduce that although it...
Homework Statement
I have been stuck on this for weeks
Homework Equations
∫E.dl = -dφ/dt
The Attempt at a Solution
Total EMF (V) = -dφ/dt (Where φ is the magnetic flux through the loop)
⇒V = -A(dB/dt) (Since Area remains constant)
⇒V = -Ax (x=dB/dt)
⇒V = -2xl^2
I do not know how to proceed.
Homework Statement
The figure below shows a small circular loop of wire in the plane of a long, straight wire that carries a steady current I upward. If the loop is moved from distance x_2 to distance x_1 from the straight wire, what will be the direction of the induced current in the loop and...
Homework Statement
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I encountered this problem during my exam. A coil of 50 turns, each with area 0.02m2 is rotated in a uniform magnetic field of magnitude 0.4T. The coil is rotated at a frequency of 60Hz. Given the average power generated is 50W, what is the resistance of the wire...
I know that the right hand rule applies for induced currents, and the left hand rule is for motors, but why? It doesn't seem to connect with any other physics laws and is very counter-intuitive that the current will flow in one direction rather than the opposite direction if both are...
Homework Statement
suppose a coil is placed in a changing magnetic field and the circuit is not closed will the current induce in the coil
Homework Equations
The Attempt at a Solution
What I thought was that the current flows only in a closed circuit because it needs a potential difference...
Homework Statement
Homework Equations
The Attempt at a Solution
The emf gets induced due to the changing flux.
The flux through the rod remains 0. So, there is no induced emf.
I don’t know how to calculate induced electric field.
But as there is no induced emf, so there is no induced...
Suppose there is a coil around a C-shaped iron core with a dipole magnet in the gap as shown in the dynamo below. As the magnet is spinning, in order to oppose the force, a changing pole is produced in the iron. (Eg. As N-pole approaches the iron core, a north pole is induced to oppose the...
Homework Statement
A homopolar generator consists of a metal disc of radius ##a## and a central axle which has radius ##a/4##. The disc has resistivity ##\rho## and thickness ##t##. It is rotated in a uniform magnetic field ##B## about an axis through the centre, which is parallel to ##B## and...
Homework Statement
We have a coil with cross-sectional area of 2.4m^2.
Magnetic flux density is of 0.29T
Number of turns are 1.
Initially the coil is parallel to magnetic field lines. (Coil's normal vector is perpendicular to field vector)
Calculate the change in magnetic flux when coil is...
In Purcell- Electricty and Magnetism book, in the chapter on electromagnetic induction, I found the following explanation regarding the magnetic flux through a circuit of area ##S##.
Consider the circuit in figure, moving in a time ##dt## in a magnetic field ##B##, constant in time (but not...
I just read in my textbook that it is impossible to harness electricity from the induced emf if the velocity of a conductor is parallel to its straight length. Let me elucidate further: a magnetic field goes into the page and a straight conductor is moved straight down or up (perpendicular to...
since graphite conducts. if spiral shape is drawn with pencil on the wall (thick , dark lines)
will a voltage difference appear between inner and outer end of the spiral when a varying magnetic field is switched on, normal to wall
Homework Statement
A circular loop of wire is placed next to a long straight wire. The current I in the long straight wire is increasing. What direction is the current that's induced in the circular loop?
Homework Equations
The Attempt at a Solution
I'm aware that the answer is clockwise...
When I induce magnetic flux through a closed loop, I should expect the lines of flux produced by current in that loop to oppose the change of flux through that loop. But what happens when that loop, say a rectangular loop, is curved into the shape of the letter J (like a candy cane) and my flux...
Dynamos and transformers have inductor coils reacting with changing magnetic fields and importing energy into the circuit in form of induced current
1. What about the counterpart of above principle in case of capacitors?
2. Will capacitors interact with...
What is emf in the coil? As far as I know about emf is that it is potential difference between two terminals of a source but what if it is induced in coil by changing flux linkage. What exactly happen when emf is induced?
Homework Statement
Two coencenteric metalic shell has inner radius $r_1$ outer radius $r_2$. We place along axis infinity wire has $\lambda$ charge in per unit length. The inner region of metalic shells inserted with relative permabilitty coefficent $\epsilon$. This system rotates with $\omega$...
Say you have a coil connected in a closed circuit. You then move a magnet inside of the coil and it remains stationary inside of the coil. Is the magnet, even though it is stationary, still inducing an emf in the coil or is it not? I'm guessing it doesn't induce an emf in the coil because...
1. The two rotors (purple, green) are electricaly isolated but mechanically fit to rotate along same axis
2. The motor action on the left side rotor will move the armature set, this will produce currents in right side rotor that will pass via a variable load.
3. do you see the magnetic fields...
1. Imagine a big river with water flowing constant velocity , assume there is a whirlpool at center as shown in the figure.
2. Because of the magnus force the whirlpool should move towards left or right towards river bank depending on the spin, but it does't happens it just stays fine in its...
Hi Experts,
I'm doing an experiment of Electromagnetic Induction (producing current by changing magnetic field i.e. by circulating magnetic wheel of N52 Neodymium Magnets around copper coil),
but what i found
when the speed of wheel is HIGH, the Output Current is LOW (in range of .02...
Homework Statement
Hi, so during an experiment, I spun a magnet inside a coil of wire in order to induce an emf, and measure the input power and output power. One of the things I found was that the slower the magnet spun (ie the smaller the input voltage to the motor) the larger the induced...
Homework Statement
Please see the attached file.
Homework Equations
$$\frac{dΦ}{dt} = ε$$
The Attempt at a Solution
The only way I see is to apply some conservation of energy. But I don't know how. The potential energy is being converted to rotational energy. But how do I find the potential...
I am fixed to find out the reason what makes the charges get separated in conductor causing an emf leading to induced current. A very good reason exists for motional emf. It can be explained with the help of F=qvBsinΘ.
Hi everyone. I have a question that I would be grateful to receive your insights on.
In our bedroom, we have a LED strip running from a typical 12V transformer. We turn it off at night using the controller box, which is in between the LEDs and the transformer. The thing is, a couple of times...
Hi all,
I am designing an NFC device but am still a little unsure about the principles behind NFC/RFID. From what I understand:
A primary coil constantly emits a 'carrier frequency' magnetic field.
This field induces an e.m.f. on a passive secondary coil which is in a secondary circuit.
The...
If we have a conducting loop, and a magnet (say North pole first) is pushed into it; that induces and emf and hence a current in the coil due to the changing magnetic flux, right? According to Lenz' law, the direction of the current is such that it opposes the change. So from the side the magnet...
when A current-carrying conductor is placed in A magnetic field due to the interference of both magnetic fields,the field is made variable so a force will be induced on the Conductor.
so my question is, If an Ac current is passed through conductor it will have variable magnetic field will it...