What is Electromagnetism: Definition and 838 Discussions
Electromagnetism is a branch of physics involving the study of the electromagnetic force, a type of physical interaction that occurs between electrically charged particles. The electromagnetic force is carried by electromagnetic fields composed of electric fields and magnetic fields, and it is responsible for electromagnetic radiation such as light. It is one of the four fundamental interactions (commonly called forces) in nature, together with the strong interaction, the weak interaction, and gravitation. At high energy, the weak force and electromagnetic force are unified as a single electroweak force.
Electromagnetic phenomena are defined in terms of the electromagnetic force, sometimes called the Lorentz force, which includes both electricity and magnetism as different manifestations of the same phenomenon. The electromagnetic force plays a major role in determining the internal properties of most objects encountered in daily life. The electromagnetic attraction between atomic nuclei and their orbital electrons holds atoms together. Electromagnetic forces are responsible for the chemical bonds between atoms which create molecules, and intermolecular forces. The electromagnetic force governs all chemical processes, which arise from interactions between the electrons of neighboring atoms. Electromagnetism is very widely used in modern technology, and electromagnetic theory is the basis of electric power engineering and electronics including digital technology.
There are numerous mathematical descriptions of the electromagnetic field. Most prominently, Maxwell's equations describe how electric and magnetic fields are generated and altered by each other and by charges and currents.
The theoretical implications of electromagnetism, particularly the establishment of the speed of light based on properties of the "medium" of propagation (permeability and permittivity), led to the development of special relativity by Albert Einstein in 1905.
In superconducting state, If the superconductor and the guide line are stationary, will the force between the the guide line and the superconductor change when they are close to or far away from the magnet?
As shown in the figure, the aircraft includes a geomagnetic field convergence layer, which is a superconductor material. The geomagnetic field convergence layer repels the direction of changing the geomagnetic field, so that the geomagnetic field passes between the upper and lower converging...
Hello! I'm working on an online assignment and am on my last chance to submit the right answer, so I figured I'd ask here for some help to see where my reasoning is wrong.
Problem:
For each of the five questions, I can choose one of four responses: Positive, Negative, Neutral, or Cannot Tell...
Consider an electric dipole consisting of charges ##q## and ##-q##, both of mass ##m##, separated by a distance ##d##.
If the dipole is given an acceleration ##a## perpendicular to its moment the total electric force on it, due to each charge acting on the other, is given approximately by...
Particles follows accordingly the general equation:
$$
m*\overrightarrow{a}=q*\overrightarrow{E}+q*\overrightarrow{v}\wedge \overrightarrow{B}
$$
But in the case of two coupled coils the time varying current at primary coil (and its magnetic field variation) creates corresponding varying...
I am contemplating writing a science fiction story involving flexible barriers that can be erected in a very short time. Force fields are pervasive in science fiction, but from what little I've read, they're not very plausible.
Is there a flexible material, or class of materials, that...
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Hi everyone! My name is Alexandra, and I'm new in this forum. I am trying to determine the mentionated tensor without the assumption of linear media or vacuum ( ## \textbf{D} = \epsilon \textbf{E} ## and ## \textbf{B} = \mu \textbf{H} ##). What I want to obtain is the...
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A charged particle has an electric field at ##\langle -0.13, 0.14, 0 \rangle## m is ##\langle 6.48\times10^3, -8.64\times10^3, 0 \rangle## N/C. The charged particle is -3nC. Where is the particle located?
Homework Equations
##\vec E=\frac 1 {4π\varepsilon_0} \frac q {|\vec...
I'm studying for an exam (so this is existential) and I never really got how to write the limit conditions for an interface.
In my problem, there is an incident electric field, and there are two cases:
1) the field is polasised perpendicularly to the incidence plane (TE)
2) polarised in the...
Hi everyone, I have a question that can't solve. Does exist a lagrangian for the relativistic angular momentum (AM)? I can't even understand the question because it has no sense for me... I mean, the lagrangian is a scalar function of the system(particle,field,...), it isn't a function FOR the...
How can it be easily shown that it's a bad idea to develop relativistic gravitational theory in full analogy with electromagnetism? I.e. why not to introduce 4-potential for gravitation in analogy with 4-potential in covariant form of Maxwell equations and get something fully analogous to...
I was studying Feynman Lectures on Physics Volume 1 chapter 29. In there he proves that electric field propagates like a wave. Here is my attempt (in image), please tell me my mistake.
Thank you
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So I'm really confused with mutual inductors and dot convention. If your answer is going to be a link to any website I can assure you I read them all and that only left me more confused. So here are my questions:
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3. The Attempt at a Solution [/B]
->...
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I'm working through an example with motional EMF and I'm having trouble understanding the directions of vectors so that I can apply induction law.
The magnetic circuit seems complex because the circuit is used to analyze other situations but the air gap 3, the coil 3 and the...
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I'm currently studying induction law and circuits with inductors. I came however with the following circuit:
[1]: https://i.stack.imgur.com/ghaiE.png
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3. The Attempt at a Solution [/B]
Now my text says the following:
"Unlike what your intuition might...
(Hope I posted in the right section)
Hi, starting from next semester I will have to attend classes that require a "decent" understanding of electromagnetism. I know very little about it though (it's a very long story...) so I started to study Griffith's book. At least I know the mathematics...
Hello,
There is a common setup used when describing the intimate relationship between electricity and magnetism. I have a question about the setup.
Setup:
There is some long current-carrying wire. Outside of that wire, there is some test charge.
In the first situation, the test charge is...
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It is clear that SOMETHING exerts a force on the conducting wire in a downwards direction.
By Newton's 3rd law, the (field of) this conducting wire also exerts a force on something.
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Could the magnet be said to move upwards (and hence reading decrease)...
Hello, I just had a quick question. Does anyone have links to online lectures for Upper-Division Electromagnetism? I so far haven’t been able to find much other than a few isolated videos here and there. I’m looking for something that covers Legendre polynomials, spherical harmonics, maxwell’s...
Hello
To develop one interesting idea I need to be able to do calculations on (1) scattering of light from bodies in arbitrary motion, possibly at relativistic speeds; (2) Propagation of light in electromagnetic media that are in arbitrary motion (possibly relativistic). For example, I would...
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Consider an infinitely long cylindrical rod with radius a carrying a uniform charge density ##\rho##. The rod is surrounded by a co-axial cylindrical metal-sheet with radius b that is connected to ground. The volume between the sheet and the rod is filled with a dielectric...
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The Attempt at a Solution
The textbook says that the electric field on a surface of a conductor is: . So, I guess since the sphere is metallic I can assume that what I have written there is true?
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Two magnetic materials are separated by a planar boundary. The first magnetic material has a relative permeability μr2=2; the second material has a relative permeability μr2=3. A magnetic field of magnitude B1= 4 T exists within the first material. The boundary is...
Recently ( due to me moving forward with my undergraduate studies in electrical engineering ) I purchased a plethora of books, aimed at self study, in an attempt to try and understand the concepts behind electrostatics, electrodynamics, and magnetostatics etc. I read reviews on books that would...
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A straight wire of length 0.20m moves at a steady speed of 3.0m/s at right angles to a magnetic filed of flux density 0.10T. Use Faraday's law to determine the e.m.f. induced across the ends of a wire.
Homework Equations
E= Nd Φ/dt but N=1 so E= dΦ/dt
The Attempt at a...
I would very much appreciate a clarification on what is meant by a changing electric field in the context of statements such as 'a changing electric field creates a changing magnetic field'. My question is does the electric field actually need to reverse as a lot of examples show where two...
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Griffiths' Introduction to Electrodynamics problem 2.10,
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Gauss' Law, ##\int_{S} \textbf{E}\cdot \textbf{dS} = \frac{Q_{\text{enc}}}{\epsilon_0}##[/B]The Attempt at a Solution
It seems reasonable that the flux through the shaded surface and the front...
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Suppose we have a regular n-gon with identical charges at each vertex. What force would a charge ##Q## at the centre feel? What would the force on the charge ##Q## be if one of the charges at the vertices were removed? [/B]Homework Equations
Principle of Superposition, the...
I have just finished my first semester of third year undergraduate physics, and have a 3-4 week break before my next semester, in which I will be taking a third course in electromagnetism (classical electrodynamics). It is my second course with a full focus on electromagnetism, since in first...
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Consider a cylinder of thickness a=1 mm and radius R = 1 cm that is uniformly magnetized across z axis being its magnetization M= 10^5 A./m. Calculate the bound currents on the cylinder and, doing convenient approximations, the B field on the axis of the cylinder for z=0...
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...
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A plane z=0 is charged with density, changing periodically according to the law:
σ = σ° sin(αx) sin (βy)
where, σ°, α and β are constants.
We have to find the potential of this system of charges. Homework EquationsThe Attempt at a Solution
[/B]
I...
Hello all,
I have a question regarding Maxwell's Equations and Faraday's unipolar induction equation.
If we study the case of a cylindrical magnet with a radius of r which is rotating about its axis
with angular velocity w. The electrons within the magnet collide with the moving atoms, causing...
Good afternoon,
I am carrying out a practical magnetism project which involves 2 small (2mm x 2mm - 0.6kg) neodymium magnets attached together, and an electromagnet to create a push-pull force from below in order to part them. For those that also build model railway/railroads, this will be a...
Hi I just saw this video . Here it's said that that electromagnetic force is just a consequence of special relativity, but I don't get the explanation. According to the video the electromagnetic force is generated by relative motion of charges, so it is essentially an electric force. It doesn't...
Hello.
I have an assignment to submit and I really want to get full marks/know where I went wrong
If anyone has a tiny bit of free time would you mind please checking my homework?
Even if you just check 1 page I will be so grateful.
Thanks again
https://imgur.com/a/rHVdjzn
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I have a simple problem relating to the superposition of plane EM waves that I'd to try out using complex notation. Could anyone run through the work to see if my understanding is right?
Many thanks in advance!
The incident E bit of the wave is
$$\vec{E}_I = E_0 \sin(ky -...
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A cylinder with radius ##R## and height ##h## which has a distributed charge on its surface with density ##\sigma## spins over its axis with angular velocity ##\omega##.
If the cylinder has a mass density ##\rho##, find the relationship between magnetic momentum and angular...
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Let’s say I have got a charge density $\rho (x,y,z) = \cfrac{C}{x^2}$ with C a specific constant. I want to know the potential on every point in space. How can I get an expression of the electric potential in terms of position?
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Gauss law/coulomb's law...
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Determine the B-field inside the middle of a circular loop of current.
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Attempt at using Ampere's law: ##\oint \vec{B} \cdot d \vec{l} = \mu_0 i##
The Attempt at a Solution
##\oint B \cdot R d \theta = \mu_0 i \Rightarrow BR(2 \pi) = \mu_0 i \Rightarrow B...
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Example 5.9 in Griffiths's Introduction to Electrodynamics 4th shows us how to find B of a very long solenoid, consisting of n closely wound turns per unit length on a cylinder of radius R, each carrying a steady current I. In the solution, he goes on to explain why we don't...
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In an electromagnetic filed, the elctric field ##\vec{E}## forms an angle ##\theta## with the magnetic field ##\vec{B}##, and ##\theta## is invariant for all inertial observers. Finding the value of ##\theta##.
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Tranformations of fields perpendicular to the...
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Given an electromagnetic tensor ##F^{\mu\nu}##, showing that:
$$\det{F^{\mu}}_\nu=-(\vec{B}\cdot\vec{E})^2$$
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The Attempt at a Solution
I had only the (stupid) idea of writing explictly the matrix associated with the electromagnetic tensor and calculating...
I started studying the book "A Student's Guide to Maxwell's Equations" by Daniel Fleisch some time back. It is an excellent book, giving a very good idea about the main laws of electromagnetism.
I will soon finish the book. Now I need some book(s) which has problems on all the laws in classical...
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Homework EquationsThe Attempt at a Solution
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I got the first 2 parts, but I'm having trouble with the last one. For the time the switch S1 is closed, I derived ##q(t) = CE(1 - \cos(\frac{t}{\sqrt{LC}}))##, by writing the loop equation ##\frac{E}{L} - \frac{1}{LC}q =...
I wrote and solved this problem but am having serious doubts about the answer I obtained.
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Two point charges \pm q move along the z-axis with velocity \pm v. If they are at the origin when t=0, what is the electric field magnitude a distance r from the z-axis?
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Some background info: I am an international student that is currently studying at a supposedly prestigious university (Top 20 in QS and Times Higher Education ranking). As part of my major requirement, I am taking an EM module. The problem is, my forte is not really physics (I am an IBO...
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A straight copper wire that carries a sinusoidal current with an alternating frequency of 50 Hz and a maximum amplitude of 0.5 A passes through the centre of a circular ring of a second copper wire, with the two wires orientated perpendicularly to each other. The radius of...