What is Electromagetism: Definition and 283 Discussions

Consider a waveguide with axis parallel to axis ##z##. Using cartesian coordinates the fields inside the waveguide can be written as Where ##\alpha## is the wavenumber and ##k=\frac{\omega}{c}## . The maxwell equations ##\nabla \times E=-\frac{\partial B}{\partial t}## and ##\nabla \times...

How does look like electric field lines due to change of the uniform magnetic field? Suppose we have a magnetic field between two infunite plates with surface current $i$ which is lineary change with time. Then B-filel is (x - perpendicular to plates, z and y along plates) \begin{equation} B_z =...

Hello! Recently I was going through some old exams and upon encountering this problem (which seemed pretty easy) I got stuck. Exams at my university are composed of individual tasks, each having three subquestions with four plausible answers respectively. Solution sheet gives results only, so...

An interesting problem posed to me by a friend: A small sphere, initially neutral, of radius ##a## emits ##n## charges ##q## of mass ##m## per unit time isotropically from its surface at a radial velocity of constant norm ##v##. Determine the spatial distribution of charges and currents at...

Hi guys, I am trying to produce a desktop feature for a client which consists of a 3d printed cube with a metal ball at its center. I can suspend the ball in the center of the cube using a support or piece of rod, but I would really like to try and make it levitate using an electromagnet. I...

Homework Statement Homework EquationsThe Attempt at a SolutionThe position of the point (where V is to calculated) on the z-axis would be ##u = z_0 + l/2##.So in cylindrical coords, $$V(u) = \int_V {k \rho \over (s^2 + (u -z)^2)^{1/2}} dV = k \rho \int_0^L \int_0^{2\pi} \int_0^R {k \rho...

Hi, I was wondering, as in the Bachelor's degree curriculum there is no SR course, for one who is interested in theoretical physics (as me), would do it alone, perhaps with texts such as Rindler or Synge ...? Thank you in advance !

Homework Statement [/B] A proton is accelerated from rest at the positive plate of two charged parallel plates with a potential difference of 2000 v. After leaving the plates through a small hole in the negative plate, it enters a uniform magnetic field of 0.50 T in a direction perpendicular to...

I've been following the derivations in the following video up until that point. I don't quite understand why does it imply that μ*ε=1/c^2. Thanks.

Hi, I've 2 em texts: Purcell, ( Electricity&magnetism ) and the Griffiths (intro to electrod.) On which of the two, is best to study ?

Homework Statement We have two metal spheres of radii ##R_1## and ##R_2## placed far apart. Given total amount of of charge ##Q## to distributed between the two spheres, how should you do it so that the potential of given distribution is as small as possible. Homework EquationsThe Attempt at a...

I want to prove ##\displaystyle U = {1\over 8\pi}\int \vec E \cdot \vec E dV## and ##\displaystyle U = \frac12 \int \phi \rho dV## are equal. I started with ##\nabla \cdot (\phi \nabla\phi) =(\nabla \phi)^2 + \phi \nabla^2 \phi##' Then ##\displaystyle {1\over 8\pi}\int \vec E \cdot \vec E dV...

From the book, I did not understand, 1. Why does fields coming inwards the sphere contradicts the Gauss law ? 2. I am unable to connect the potential picture and electric field picture. Why does the point P must have lowest or highest potential than neighbouring particles ? 3. I understand...

Homework Statement I have an elementary doubt with the calculation of the capacitance of a capacitor of parallel plates that has a dielectric in the middle. https://ibb.co/b0W4BQ Homework Equations ∫D⋅ds=Q D=E+γP C=Q/V The Attempt at a Solution Suppose the top plate has a positive charge...

Homework Statement Solve by integration method :- From a spherical shell of radius ##a##, a circular disk of radius ##b## has been removed. The shell has a surface charge density ##\sigma##. Find the Electric field through that aperture. Homework EquationsThe Attempt at a Solution We put the...

As I understand it, the classical source-free electric, ##\mathbf{E}## and magnetic, ##\mathbf{B}## wave equations are solved by solutions for the electric and magnetic fields of the following form: $$\mathbf{E}=\mathbf{E}_{0}e^{i (\mathbf{k}\cdot\mathbf{x}-\omega t)}$$...

Maxwell equation in absence of charges and currents are $$\nabla \cdot \bf{E} = 0 \\ \nabla\cdot B=0 \\ \nabla \times E=-\frac{\partial B}{\partial t} \\\nabla \times B=\mu \epsilon \frac{\partial E}{\partial t}$$ Wave equation is $$\nabla ^2 \bf{E}=\mu \epsilon \frac{\partial^2...

Homework Statement Consider two long parallel wires each of radius a with a separation distance d between them. They carry current I in opposite directions. Calculate the magnetic flux through a section of length l, ignoring magnetic field inside the wires. My confusion lies in trying to...

Homework Statement This is from the book Engineering Electromagnetics by Hayt & Buck.[/B] Homework Equations E = - (ΔV/ΔL)[/B]The Attempt at a Solution At part (a), I took the potential difference between point A and the point directly above at the higher surface (106 V) and plugged in the...

I have a question regarding the voltage of two different circuits. In the first circuit there is a 75 volt battery with just one 4 ohm resistor. In a separate second circuit there is a 75 volt battery again, but this time there is a 4 ohm resistor and 9 ohm resistor in series. My question is...

Homework Statement The dielectric cylinder is radius R and thickness d. Origin is at the center of the cylinder, which is oriented along the z-axis. It has polarization P=pz∧I need to calculate the potential V(0,0,h) at h>d/2. Homework Equations σb=P⋅n∧...

Homework Statement The cylinder has a radius a and is perpendicular to the electric field, E(r)=E(x_hat). It also carries charge Q. The potential is of the form V(r,φ)=A0+A0'ln(r)+∑(n=1 to ∞)((Ancos(nφ)+Bnsin(nφ))rn+(An'cos(nφ)+Bn'sin(nφ))r-n) Homework Equations V=-∫E⋅dl The Attempt at a...

What composes the E Field of the Electromagnetic Wave where "disturbances" for propagation occurs? If electromagnetic waves cause disturbances in the Electric Field… what “is” in this E Field which photons Interact with? I ask because in Vacuum, there are no electrons to excite. So what is...

Homework Statement There's a charged semicircle, the ends of which are on the x-axis and it extends into the positive y-axis. It has uniform line charge density. I need to find the electric field at an arbitrary point on the x-axis that's not the origin. Homework Equations I don't know. The...

Homework Statement I got an alpha particle (charge 2+) fixed at x=0 and an electron fixed at x=2. I then add a fluor ion (charge 1-) to the right of the electron and we note his position xeq. The question is to find the constant spring (k) relative to the harmonic oscillation made by the fluor...

How much importance does light (electromagnetism) have to do with the "Observer Effect" in the Double-slit experiment? From my research, it seems that the only successful "Observer Effects" in the Double-slit experiments, wherein, the interference pattern transitions to a clump pattern, is...

1. A uniform bar has mass 0.0180 kg and is 30.0cm long. It pivots without friction about an axis perpendicular to the bar at point a (as seen in the diagram). The gravitational force on the bar acts in the −y-direction. The bar is in a uniform magnetic field that is directed into the page and...

Homework Statement Suppose a magnetic monopole q_m passes through a resistanceless loop of wire with self-inductance L. What current is induced in the loop? Homework Equations \nabla \times \textbf{E} = - \mu_0 \textbf{J}_m - \frac{\partial \textbf{B}}{\partial t} \nabla \cdot \textbf{B} =...

Hi. I have a rather silly question. When speaking about a single photon? What do people mean when they speak of the polarization of a single photon. For instance, in classic electromagnetic theory, this would be the direction in which the electric field of the wave is oscillating . But does...

I am trying to calculate the magnetic field generated by an ideal toroidal solenoid by using the integral of the Biot-Savart law. I do not intend to use Ampère's circuital law. Let ##I## be the intensity of the current flowing in each of the ##N## loops of the solenoid, which I will consider an...

1. Passage of current via coil creates magnetic field (fig a), similarly external magnetic field linked to coil when changed created electric current in the circuit connected ( Faraday's em induction fig b). 2. Charging of capacitor using voltage source creates electric field in the capacitor...

Generally we use the left hand rule - (if index finger shows velocity, middle finger shows magnetic field, the thumb points towards force). Recently I also came across a left hand rule for lorentz force- Using your right-hand: point your index finger in the direction of the charge's velocity, v...

Homework Statement Suppose the nonconducting sphere of Example 22-4 has a spherical cavity of radius r1 centered at the sphere's center (see the figure). Assuming the charge Q is distributed uniformly in the "shell" (between r = r1 and r = r0), determine the electric field as a function of r...

The magnetic field generated by an infinitely long straight wire represented by the straight line ##\gamma## having direction ##\mathbf{k}## and passing through the point ##\boldsymbol{x}_0##, carrying a current having intensity ##I##, if am not wrong is, for any point ##\boldsymbol{x}\notin...

Maxwell's equations reveal an interdependency between electric and magnetic fields, inasmuch as a time varying magnetic field generates a rotating electric field and vice versa. Furthermore, the equations predict that even in the absence of any sources one can have self propagating electric and...

What is the intuition for why the frequency of light does not change as it passes from a less dense medium to a denser one (or vice versa)? Classically, if we treat light in terms of waves, then intuitively, is the reason why the frequency does not change because it is determined by the...

Hi guys I am a new member here so I am looking for feedback on the quality and clarity of this post as well as a solution to the problem. If there are any suggestions as to how I can improve the format or wording of the question I am always looking to get better. On to the question, I am...

I am kind of an arm chair layman, The following is just my own curious mind working furiously on something I know I don't completely understand, and yet want to. It seems to me that just about every piece of matter is made up of mass, and therefor has some level of electromagnetic and gravitic...

The potential difference across an inductor is supposed to be zero, but a voltmeter measures it to be L*dI/dt. Also, if the p.d is zero then the electric field in the wires of the coil will be zero and in that case, why should charges flow at all? What am I missing?

Many textbooks and online sources give the relative permittivity of water as about 80 and the refractive index as 1.33. If you use the definition of refractive index to find the speed of light in water, you will find v = c/n ~ 2.56e8 m/s. However, if you use the equation to find the speed of...

Hello, I will be taking a second course on electromagnetism and I want a book that bridges the gap between Griffith's book and Jackson's book. I have come across Panofsky's book and Nayfeh's book but I don't know which one is better. Any opinion for these would be much appreciated Thanks!

Hello, I am an electrical engineer rather than a physicist, however, I am trying to understand the physics of a twin wire transmission line in terms of the charge and current density. Let's say we have a lossless, infinite length, twin wire transmission line, a step current is induced into the...

Homework Statement An electron with velocity ##\vec{v}_0=8.7*10^4(m/s)## (in the î direction) passing through an area with a uniform magnetic field ##\vec{B}=0.80 T## (in the negative k̂ direction). There's also a uniform electric field in this area. What is the magnitude and direction of...

Homework Statement [/B] Three conducting loops, all with the same resistance ##R## move towards a uniform and constant magnetic field, all with the same velocity ##v##. Their relative sizes can be identified by the grid. As the loops move into the magnetic field an induced current begins to...

I'm trying to understand how we set up the lagrangian for a charged particle in an electromagnetic field. I know that the lagrangian is given by $$L = \frac{m}{2}\mathbf{\dot{r}}\cdot \mathbf{\dot{r}} -q\phi +q\mathbf{\dot{r}}\cdot \mathbf{A} $$ I can use this to derive the Lorentz force law...

Homework Statement A vertical column of mercury, of cross-sectional area A, is contained in an insulating cylinder and carries a current I0, with uniform current density. By considering the column to be a series of concentric current carrying cylin- ders, derive an expression for the...

Homework Statement For the magnetic circuit: Derive the circuit approximation. Compute all magnetic fluxes if the total solenoid current is I. Homework Equations Rm = L / μS The Attempt at a Solution [/B] Mostly, right now, I'm just trying to determine the magnetic circuit equivalent. From...

Homework Statement Sorry for the dull question. Problem is as shown/attached Homework Equations The waves in part ii) are traveling in a HIL dielectric of permittivity ##\epsilon_{r}## from ##0 <z<d## and then hit an ideal metal boundary at ##z=d##. The Attempt at a Solution I figure this...

Question- Two proton beams going in the same direction repel each other whereas two wires carrying current in the same direction attract each other. Why does this happen? Attempt at the solution- Two proton beams should be equal to two currents in the same direction then why are we getting two...

Homework Statement A slab of material has parallel faces. One coincides with the xy plane (z = 0), while the other is given by z = zt . The material has a nonuniform polarization P = P(1 + αz)zˆ where P and α are constants. Fin the volume and surface densities of bound charges[/B] The Attempt...