Electromagetism Definition and 280 Threads

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Can anyone please tell me why the torque on a circular current loop can be calculated by the equation below? In other words, what is the intuition for the formula? Thank you. (I modified my question to a particular case) $$ \vec{\tau} = I \vec{A} \times \vec{B} $$

In my latest 10th grade physics lesson, we were learning about the refraction of light. I decided to share what I knew about why light slows down in a vacuum, which is, in short, because the electric field of the electromagnetic wave exerts a force on the charged electrons of a medium, which in...

Let r = position of the electron = 6mm - 36.8μm; λ = mean free path traversed. Integrate E(r) = Q/(2πϵLr) between the two shells gives: V = [Q/(2πϵL)]*log(r/(r-λ)) I know that the question is asking for the voltage at which the electron energy will get to 23eV, but i am unsure how to get rid...

I am required to find the direction of the electric field on the surface of a grounded conducting sphere in the proximity of a point charge ##+q##. The distance between the center of the sphere and the point charge is ##d## and using the method of images we find that the charge of the sphere is...

I need some rigorous introductory books on Electromagnetism, by rigorous I mean detailed and mathematical. Many books that I have found don’t actually work out the field produced by current carrying toroid, solenoid or even some other simple electrostatic situations. They just write “by...

Summary:: I need to add references for several classical electromagnetism concepts, I would like to know which books deal with these concepts. Recently a paper about classical electromagnetism that I had submitted was rejected, among other reasons because it contained many references to...

Hello! In Optical fibers, let ##k_1## and ##k_2## be respectively the propagation constants in core and cladding, ##\beta## the propagation costant of a mode along the direction ##z##, ##a## the radius of the fiber. Using the normalized quantities ##u=a \sqrt{k_1^2 − \beta^2}## and ##w=a...

When we calculate the curl of magnetic field, that is the curl of Biot-Savart equation for magnetic field. Please consider these . The working of last equation $$ \nabla \times \mathbf {B} = \frac...

I am trying to answer exercise 5 but I am not sure I understand what the hint is implying, differentiate with respect to ##p_\alpha## and ##p_\beta##, I have done this but nothing is clicking. Also, what is the relevance of the hint "the constraint ##p^\alpha p_\alpha = m^2c^2## can be ignored...

There was an old thread comparing the difficulty of classical mechanics and electromagnetism. The consensus was that electromagnetism is more difficult, and substantially so according to some. The thread was no longer open for replies, but it got me suspecting that we're comparing apples to...

Since it is stated that ##E'_x = E_x##, I am going to set a special case where ##z' = z = 0##, ##E_x## in (5.10) reduces to, ##E_x = \frac{1}{4 \pi \epsilon_0}\frac{Q}{x^2}## However, ##E'_x## in (5.13) reduces to, ##E'_x = \frac{1}{4 \pi \epsilon_0}\frac{Q}{\gamma^2 x'^2}## There is an...

I am having problem with part (b) finding the vector potential. More specifically when writing out the volume integral, $$A = \frac{\mu_0}{4\pi r}\frac{dq}{dt}\int_{0}^{2\pi}\int_{0}^{\pi}\int_{0}^{?}\frac{1}{4\pi r'^2} r'^2sin\theta dr'd\theta d\phi$$ How do I integrate ##r'##? The solution...

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...

I was reading that in inverse scattering approach, we divide the region of interest into discrete grids and size of each grid should be much smaller than the incident wavelength (usually smaller than one-tenth of wavelength). By this logic, theoretically, I can use inverse electromagnetic...

Can someone provide me intuitive visualization of how E or H field can be longitudinal in a waveguide (TM/TE)? TEM is easy to visualize, but how EM wave can behave like sound in a waveguide (constant phase and amplitude plane in the same direction)? [Moderator: large bold font removed. In the...

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 =...

For reference, this is from Griffiths, introduction to quantum mechanics electrodynamics, p253-255 When deriving the ideal magnetic dipole field strength, if we put the moment m at origin and make it parallel to the z-axis, the book went from the vector potential A $$ A=...

Does anyone know the answers to this, or can hopefully guide me to a text that will help me solve this aharonov-bohm problem? Here is the given: Particles (of mass m, and charge q), are driven through two slits that have distance d between them, in a screen that is far away (L>>d) from the...

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Hi everyone, I'm pretty new to electromagnetism and have no experiences in this topic. I have a signal generator (Digital Dual Channel Funktion Signal Generator) and want to generate two signals (530 and 550 Khz signal) and want to transmit these generated signals to the points on a table...

I know the current of capacitor and inductor must be parallel but pointing in opposite direction due to the fact they are connected in parallel thus having same voltage (please see attached screenshots). The current of resistor will simply be the sum of these two vectors, but what about its...

Under Newton, gravity is what I term an "invisible magic rope" that pulls you down. Enter Einstein. We do away with the invisible magic rope, and say that space (or space-time) is warped by mass. However, we still have other forces, that (as far as I know, anyway) are "invisible magic ropes."...

While going through an article titled "Reflections in Maxwell's treatise" a misunderstanding popped out at page 227 and 228. Consider the following equations ##(23\ a)## and ##(23\ c)## in the article (avoiding the surface integral): ##\displaystyle \psi_m (\mathbf{r})=-\dfrac{1}{4 \pi} \int_V...

I'm confused by this question, from minimal coupling shouldn't the answer simply be ## \nabla^a \nabla_a F_{bc} = 0 ##? Any help would be appreciated. EDIT: I should also point out ##F_{ab}## is the EM tensor.

In a certain region for which σ=0, μ=2μ0, and ε=10ε0, J= 60sin(109t - βz). Determine D, H, and β.

Suppose we take a charged particle and a magnet and place them at some particular distance apart .Now let's take 2 frame of reference. [the charged particle and the magnet are in rest with respect to each other through out the whole event]{both of the frames are inertial} frame(a): this frame...

Destructive interference is excellently demonstrated in Young's double slit experiment, where dark regions are formed due the waves being out of phase. However, what really confuses me is that unpolarised light has intensity. Assuming we had perfectly unpolarised light, as in where the...

Homework Statement Suppose we have an isolated, long, narrow straight wire with low electrical resistivity. A constant current ##I## is sent through this wire. We know that if an electron is sent on a path which is perpendicular to the wire, towards it, with an initial speed ##v_0##, and the...

Homework Statement A cork ball is suspended at an angle from the vertical of a fixed cork ball below. The mass of the suspended ball is 1.5x10^-4 kg. The length of the suspension thread is .1m. The fixed ball is located .1m directly below the point of suspension of the suspended ball. Assume...

Homework Statement a) A point charge + q is placed at the origin. By explicitly calculating the relevant line integral, determine how much external work must be done to bring another point charge + q from infinity to the point r2= aŷ ? Consider the difference between external work and work...

Hi, I just finished studying Maxwell's equations. Based on my understanding, when you solve maxwell's equation, you get the wave equation and it simplies to in a charge and current-free region. I understand that these two equations are similar to an equation of a wave in space. What I am...

Hello, In the sources I have looked into (textbooks and articles on differential geometry), I have not found any abstract definition of the electromagnetic fields. It seems that at most the electric field is defined as $$\bf{E}(t,\bf{x}) = \frac{1}{4\pi \epsilon_0} \int \rho(t,\bf{x}')...

I'm working on a project and came across electromagnetic braking recently and I'm really curious to know if it's really feasible. The project in brief is a vehicle on a monorail at speeds of +600km/hr needs to be stopped. The monorail is made of an alloy of aluminium. I have no background in...

Just for the record, The text is Introduction to Electrodynamics (4th Edition) by David J. Griffiths Chap.6. What does "when the magnetic dipoles are aligned" mean? Does it mean Both moments are parallel to each other's magnetic field? i.e. ##m\times B = 0## for both? Or is it ##m_1\parallel...

In many texts I have seen, Gauss theorem has the form of$$\frac{q}{\epsilon_0}=\oint\vec{E}d\vec{A}$$ Why a line integral symbol was used for this surface integral everywhere? The more I see it the more I believe there is something wrong with my understanding about this. I didn't think too much...

Are both magnetic fields emanated from an electromagnet fed with a current spike from a charge capacitor and a rotating static magnetic field from permanent magnets instances of time varying fields? The permanent magnet would be attached to perhaps some rotating disc thus passing over a target...

Homework Statement I need help on solving this exercise : We have a ring of radius = ##a## uniformly charged (total charge = ##Q##) and on its axis a segment ##OA## (length = ##a## also) of uniformly distributed positive electric charges with the charge density ##\lambda'## and of total charge...

What is the value of the permeability constant in 1865, the time when Maxwell's theory was first published? What was the experimental method used to determine the constant. Who did the experiment.

I'm sorry if this question is a little abstract, but would appreciate any guidance! It's for a DIY project I am considering. Suppose you have a flat panel mounted on a wall, and a very strong magnet that will move in any direction on the plane of the flat panel. Through any possible arrangement...

Homework Statement Show that the radiation field is transverse, ##\vec{\nabla}\cdot\vec{A}=0## and obeys the wave equation ##\nabla^2\vec{A}-\frac{1}{c^2}\partial_t^2\vec{A}=0##. You should start from the expansion of the quantum Electromagnetic field. Homework Equations ##H=\frac{1}{2}\int...

Homework Statement Use Maxwell's equations to elaborate an coherent explication of why electromagnetic waves propagate independently of the source that produces them. Homework Equations Maxwell's equations in vacuum: ##\nabla * E=0## ##\nabla * B=0## ##\nabla \times E = -\frac{\partial...

Homework Statement consider a toroidal electromagnet with an iron ring threaded through the turns of wire. The ring is not complete and has a narrow parallel-sided air gap of thickness d. The iron has a constant magnetization of magnitude M in the azimuthal direction. Use Ampere's law in terms...

Hello, I'm boy who suddenly been strucked by curiosity on how hand crank generator works and i watch and read some of how to create one, specially this one on youtube: and i want to create one but i don't have a 3D printer, but i saw some alternative but as i do/design my own coil based on...

i have heard how our broadcasts will be seen by aliens far away or whatever. but i realize those signals are going to "attenuate" by d^-2 anyway... how come in astronomy we can see light sources millions of light years away? shouldn't those signals be far too weak to detect after such a long...

<Moderator's note: Moved from a technical forum and thus no template.> Hello all, Earlier today I had an electromagnetism exam, and it seems to me that this problem is unsolvable. There's just too little information given. A proton enters an uniform magnetic field. It's initial speed v is...

Hello, I will be starting my junior year this August, I shall be having the dreaded advanced electromagnetism course that follows Jackson's book the coming semester. Unfortunately, I didn't work very hard during my freshman year e/m course (which uses Griffiths' book) and have a few gaps in my...

Hey folks! I have a degree in Electrical,Electronics and Communication Engineering and I work in Computer networking/Cybsersecurity field. Lately, I met one guy and we both decided to do some indepdendent research in electromagnetism as we both have fare amount of love for Physics( I'm in...

Copyright strictly reserved to Prof. Harbola and Nptel, Govt. of India. Lectures: http://www.nptel.ac.in/courses/115104088/# Syllabus: http://www.nptel.ac.in/syllabus/115104088/

Copyright strictly reserved to Prof. Harbola and Nptel, Govt. of India. Lectures: http://www.nptel.ac.in/courses/115104088/# Syllabus: http://www.nptel.ac.in/syllabus/115104088/