Electromagnetism Definition and 829 Threads

The Faraday Tensor is given by: Consider the following outer product with the 4-potential: The Faraday Tensor is related to the 4-potential: F^{mn} = \Box^{m} A^n - \Box^n A^m For example, ## F^{01} = -\frac{1}{c} \frac{\partial A^x}{\partial t} - \frac{1}{c}\frac{\partial...

Homework Statement Assume that the power radiated by the television transmitter uniformly fills the upper hemisphere. A UHF television with a single-turn circular loop antenna of radius 8 cm requires a maximum induced voltage above 24 mV for operation. The speed of light is 2.99792 × 108 m/s...

Homework Statement A coaxial transmission line consists of an inner cylindrical conductor of radius 1mm and a cylindrical outer conductor chosen to make the characteristic impedance 75 ohms. The space between the conductors is filled with a gas that can stand a maximum field of 10^5 Vm^-1...

Hello! Which are the highest theoretically possible electric and magnetic vacuum field strengths E and H? How are they calculated?

If an electric charge is moving with constant velocity,what does it create?? A constant magnetic field or 1 which is varying with time?? What if it accelerate?

Homework Statement Now, ignore the lengths given in the photo. Height (y) = .640 meters Length (z) = 1.18 meters Base (x) = .320 meters Magnetic Field (B) = 3.5 Teslas in the +X direction Homework Equations The problem is to find the magnetic flux through the surface of the...

That is probably a badly worded question but I understand electrostatics and I want to send simple but efficient radio signals. If I switch on a strong charge in one place it'll effect a charge away from it depending on "Coulomb's law". How is this equation expanded to explain more efficient...

I want to send radio waves through distances of 0 to 10 miles, maybe even hundreds of miles eventually. What book should I buy to educate myself? I am not really interested in doing complicated things with electricity unless it translates directly into something which will improve the...

There is something I am confused about when it comes to the force between two parallel wires carrying current, specifically why when they carry current in the same direction the wires are attracted to each other. I understand that when you use Flemming's left hand rule and consider the electrons...

Hello, I am a beginner in electromagnetism. I am trying to find a vector field whose rotation equals 1 with a curl operator. If I say that the vector field is defined by V(y;2x;0) does it work? As a result, I find (0;0;1), am I right?

\mathcal{L}_M(g_{kn}) = -\frac{1}{4\mu{0}}g_{kj} g_{nl} F^{kn} F^{jl} \\ \frac{\partial{\mathcal{L}_M}}{\partial{g_{kn}}}=-\frac{1}{4\mu_0}F^{pq}F^{jl} \frac{\partial}{\partial{g_{kn}}}(g_{pj}g_{ql})=+\frac{1}{4\mu_0} F^{pq} F^{lj} 2 \delta^k_p \delta^n_j g_{ql} I need to know how...

Hi Everyone, I need to write an essay for my electromagnetism class and i was wondering if anyone has good topic ideas. My criteria is that it needs to be 10 pages and I would like something that is interesting for me to research and write about. I was thinking so far of magnetic levitation...

So I have been curious as to the exact workings of a simple D.C. electric motor, and the transformation of electric energy into motor power. I think I have a basic understanding of the topic but there are numerous gaps in my understanding. Firstly, I think I am correct in saying that as an...

So I'm currently taking electricity and magnetism and I'm expected to know how to perform a separation of variables on laplace equation in 2 dimensions.I have taken Zero differntial equations courses and I literally have no freaking idea what's going on. The book I use doesn't spend any time...

Homework Statement I'm an introductory electromagnetism course and in lab we were observing how an electric current could deflect a compass needle. however, i also noticed that the batter itself (with no wire attached, so no current) could also deflect the needle. (for ex, if you brought the...

Hello! When considering the boundary conditions for the electromagnetic field \mathbf{E}, \mathbf{H} on the surface of a Perfect Eletric Conductor we have: \mathbf{E} \times \mathbf{\hat{n}} = 0 \mathbf{J}_S = \mathbf{\hat{n}} \times \mathbf{H} the tangential electric field should vahish...

Hello! In http://my.ece.ucsb.edu/York/Bobsclass/201C/Handouts/Chap1.pdf, pages 19-20, the Love's Theorem in Electromagnetism is declared. In presence of some electric sources \mathbf{J} and magnetic sources \mathbf{M} enclosed by an arbitrary geometrical surface S, which produce outside S a...

Hello Physics forum, I have come here seeking for some experienced help about a doubt that to some extent is not letting me advance on my studies of electromagnetism. Basically is about the magnetic (B) field, and more specifically, about the force at each point of the vector field (The lorentz...

Hello all, I have a few questions and a few thoughts I think I understand that according to einsteins theory of relativity, wavelengths can be perceived differently when traveling at different velocities comparatively to when it was emitted. i.e. if something traveling close to the speed...

I suspect that Quantum Mechanics' true theory would be understood, at least partly, by what Planck's Constant unified, like how the speed of light in vacuum was derived by Maxwell's unification of electricity and magnetism as two manifestations of one fundamental force. So, if some physics-grads...

I would like to know if this formula to convert a magnet's pulling force(lbs) to kGs is correct and reliable. I got it off this website http://www.trentatron.com/landing.htm Pull Force = 0.576 x Br² x (Th) x √‾A where Br = Flux Rating in KiloGauss Th = Thickness of Magnetized Surfaces in...

I wondered if anyone had a good online reference on the covariant formulation of Maxwell's macroscopic equations and the other equations of classical electromagnetism? The wikipedia article talks about constituitive equations in vacuum, which doesn't make a lot of sense to me since M and P...

[SIZE="4"]Definition/Summary Flux sometimes means total flow through a surface (a scalar), and sometimes means flow per unit area (a vector). In electromagnetism, flux always means total flow through a surface (a scalar), and is measured in webers (magnetic flux) or volt-metres (electric...

I know that in the vector potential formulation one can use a scalar Green function (to find the said potential and from then on the electric and magnetic fields), and that this works because the components of the potential are in the same direction as those of the source - i.e. a current in the...

This bothers me, and the question is simple: If am working with a non-minkowski metric g, when raising or lowering indexes of electromagnetism quantities, for example the electromagnetic tensor F, or the vector potential A, should I use my curved spacetime metric g or the minkowski metric n?

Hi all, So basically I would like to know if it's possible. I'm a first year undergrad and I did classical mechanics first semester but I didn't do that well in it. So I'm not sure if I need to use my holidays to catch up with it before we do Electromagnetism during second semester. I would...

Hey, currently I am a high school graduate going into college in the fall, but that isn't why I am here. There has been this question eating at the back of my head. Is there some way to induce an electromagnetic field, that could then induce a current in a wire or other some such medium, to...

Recently, I was pondering over the thought that is most of the elementary particles have intrinsic magnetism, then can gravity be just a weaker form of electromagnetic attraction? But decided the idea was silly. But I googled it later and found this article [removed link to crackpot website...

In classical electromagnetism, Coulomb's constant is derived from Gauss's law. The result is: ke = 1/4πε = μc^2/4π = 8987551787.3681764 N·m2/C2 Where ε is the electric permittivity of free space, μ is the magnetic permeability of free space, c is the speed of light in a vaccuum, and 4π is...

Homework Statement A very big iron plate with the thickness 2h have, far from the plates edges, had a hole with the radius a drilled through it. With respect to the holes axis of symmetry the plate has a magnetization \bar{M} = M_0 \frac{a}{s} \hat{s} where s is the distance from the axis of...

Homework Statement Is the magnetic force the Earth exerts on a compass needle greater than, equal to, or less that the force the compass needle exerts on Earth? Explain. Homework Equations None. The Attempt at a Solution I attempted to analyze the forces as if they behaved as...

I've recently heard of an analogy between fluid dynamics and electromagnetism in which the velocity flow field is identified with the magnetic vector potential, (and therefore the vorticity is identified with the magnetic field), and the vector \omega \times v is identified with the electric...

In a video on the youtube channel "Veritasium", it is explained that an electric field and a magnetic field is basically the same thing, it all just depends on which reference frame you are observing it from. The video demonstrates that if a positive particle is traveling along side of a wire...

I understand the reasoning behind the equations ∫SJ.dS=-dQ/dt and thus ∇.J=-∂ρ/∂t. where the integral is taken over the closed surface S. However I'm a little confused about the conditions of steady currents: The book I'm using sets dQ/dt=0 and ∂ρ/∂t=0 in these cases. I don't understand this...

Hi every one. Homework Statement in french,the problem says:"déterminer la force de laplace qui s'exerce entre deux fils de courants réctilignes,indéfinis,parraléles d'intensités I et I' de meme sens".maybe in english it means:"find the laplace force that is applied between two...

about gauss law! is there any precise proof for gauss law? why ø=q/ε always regardless how the charge is distributed inside the surface and if anyone know a good book for electromagnetism please type its name for me.. thank u

Hello! I am participating in a STEM fair(I am a middle schooler), and my scientific question is : Does the angle of the particle trails increase from beta decay when you introduce an electromagnetic influence? I have been at a loss for finding a helpful site. The ones that I have come...

Homework Statement Given \textbf{E}(z,t) = E_{0}cos(kz+ωt)\textbf{i} Find B Homework Equations ∇ x E = -\frac{\partial\textbf{B}}{\partial t}The Attempt at a Solution Taking the curl of \textbf{E} gives (0, -ksin(kz+\omega t), 0) so \frac{\partial\textbf{B}}{\partial t} = (0,ksin(kz+\omega...

Hi all, can the angular frequency of a electric waves be used to determine the wavelength using the following; ω=2πf rearranging for the frequency, and using the following; E=hf=(hc/λ) or can this formula no be used as it is dealing with photons?

An Electric field has the following form in free space; E=Re{Eo exp[j(ωt-κy)\hat{i} I am confused as to why a unit i vector is in the expression for an electric field oscillating in the Y direction? and also what does the Re mean ? i was reading somewhere about it being to do with...

a 17KG cat is shot out of a hole in the side of a charged plate when the voltage is suddenly turned up to 5000V. The cat has a charge of 2.377^16c. He lands in a 3kg crate on wheels that has a µ=0.1 for o.50 meters. The crate is then put to stop by a spring 700 N/M. how much did the spring compress?

I've just finished my first term in an undergrad electromagnetism course using Wangsness as a textbook and we ended on the displacement field. I feel like Wangsness doesn't give a very good explanation of what the whole point of it actually is, and I still don't quite understand how to use it...

Homework Statement An infinite wire of linear charge density \lambda lies on the z axis. An insulating cylindrical shell of radius R is concentric with the wire and can rotate freely about the z axis. The charge per unit area on the cylinder is \sigma = -\lambda/2\pi R while the mass per unit...

electromagnetism -- interaction between the electron and the quarks Which theory explains the electromagnetic interaction between the electron and the quarks within a hydrogen atom ? Is it QED or should I look at Standard Model ?

In electromagnetism we introduce the following differential form \begin{array}{c} \mathbb{F}=F_{\mu \nu}dx^{\mu}\wedge dx^{\nu} \end{array} Then the homogeneus Maxwell equations are equivalent to: \begin{array}{c} d\mathbb{F} = 0 \end{array} And is nice, but what purpose does this have...

I have recently come across relativistic electromagnetism so I am very new to it. The situation described to me was one where a positive test charge moves above a wire with a velocity V which matches the current in the wire in both magnitude and direction. Apparently, from the test charge's...

Homework Statement Here's an image of the circuit : http://gyazo.com/b313887dea7780e1226fcc8d4796a63d 1. Explain two ways to make the bulb glow without changing the circuit. 2. Explain why an AC generator replacing the battery could also make the bulb glow. Homework Equations The Attempt at...

Imagine a set of train tracks. Now there is one bridge (a resistor) connecting the two rails in one spot. On a different spot, there is rolling axle that acts as another bridge and it makes good electrical connection with the rails creating a full rectangular circuit. This axle rolls at a...

The question I'm wanting to ask is, Why does light travel through a vacuum? This is too big of a question to start with, though. Before making this thread, I read around and tried to make a starter question.If I'm not confused by the information I've found, a fundamental reason of why light can...

Hello, I am an EE at college, and I will be graduating in (most likely) 3 semesters. Out of all of the parts of EE, I have really enjoyed electromagnetism the most and I was wondering if anyone had any insight into careers that revolve around EM. I just don't have a good grasp of what...