What is Electromagetism: Definition and 282 Discussions

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/

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/

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/

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/

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/

In basic electrostatics any charged particle will produce an electric field at every point in space, and will have electric filed lines spreading out radially. E = kQ/r^2 The Standard model of particle physics says that the Photon is the force carrier for the Electromagnetic force, just like...

Homework Statement So I have got the question below. I am asked to find the phase difference between the electric field and magnetic field of electromagnetic waves traveling in a plasma, using the electrical conductivity expression. Now I have found the frequency of the waves and I know that...

Homework Statement In Solenoid, is emf E= N. d(phi)/dt, or is it simply d(phi)/dt? Some books contain the latter one. It was not a big deal until i gave a thought about it. Since increasing the N, we are actually increasing the value of n, thus increasing B= (mu) .n.I So, by placing N in front...

Homework Statement For a medium of conductivity ##\sigma##: $$ \nabla^2 \vec{B} = \sigma \mu \mu_0 \frac{\partial \vec{B}}{\partial t} + \mu \mu_0 \epsilon \epsilon_0 \frac{\partial^2 \vec{B}}{\partial^2 t} $$ A long solenoid with ##r=b## has n turns per unit length of superconducting wire anc...

Homework Statement My electronics&physics lecture notes contain the following side note: ___ "A ladder transmission line comprises an alternating sequence of segments of two different transmission lines both of length $l$ with characteristic impedance $Z1$ and $Z2$. If the line is constructed...

Homework Statement Consider a toroidal electromagnet filled with a magnetic material of large permeability µ. The torus contains a small vacuum gap of length h. Over most of its length the torus has a circular cross section of radius R, but towards the gap the torus is tapered on both of its...

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...

Homework Statement Determine the potential that creates an undefined cylinder of radius $R$ and density density $\rho$ that is uniformly charged. Homework Equations Gauss's law. The Attempt at a Solution I know that for this problem I can use gauss because it is a cylinder, now I do not get...

I have a picture below please have a look at it. The guy is using two conducting rods placed parallel to each other and placed below it are magnets. When battey is connected to rods and a conductor is placed over them it starts to move.That works according to flemmings left hand rule. I was...

We're told that all electromagnetic radiation consists of photons. But you never hear them mentioned when discussing low-frequency radio waves. Why not? I get that, due to the low frequencies, the energy of each individual photon would be very small, so there must be lots and lots of them flying...

Homework Statement The sun has a rotational period of 25 days. Finding the rotational period if it can shrink to form a white dwarf (##R_{WD}=10^3Km##). Knowing that the density of magnetic flux of the Sun on the surface is ##1 Gauss##, finding the magnetic flux of the white dwarf. Homework...

Homework Statement Calculate the time-dependent magnetic field intensity B(t) at an axial distance r from a long, thin straight copper wire that carries a sinusoidal current with an alternating frequency of 50 Hz and a maximum amplitude of 0.5 A. Homework Equations I = Asin(\omega t) B =...

Homework Statement I only need help with part C and D Homework Equations Curl of B = mu0 J J = J free + J bound H = B/mu0 - M The Attempt at a Solution For C i, I said they're the same because free current is the same at both points. My argument is that because curl of B (at L) = mu0 Jfree...

The equation of motion for a charged particle with mass ##m## and charge ##q## in a static magnetic field is: ##\frac{d}{dt}[m{\dot{\vec{r}}}]=q\ \dot{\vec{r}}\times \vec{B}## From this, we can see that ##\frac{d}{dt}[m\dot{\vec{r}}-q \vec{r}\times \vec{B}]=0## and so the following quantity is...

Homework Statement Calculate the electric field at point ##P## if the distance from the center of an infinitely long, charged rod to point ##P## is ##a = 0.6m##; the charge density equals ##\lambda = -CX^2##, ##C=10^{-3}C/m^3##. Show all steps in finding the equation of the field, then find the...

Equation: ΣF=Σk(qi)(qj)/(r^2) Question: Considering more than a couple of particles. How can a net force on a charged particle be calculated if Coulomb's law is under the restriction of static forces? Thanks!

Dear Members, I was reading a tutorial on ferroelectricity of liquid crystals, underneath is the excrept: "For ferroelectric materials, in addition to the dielectric torque, the electric torque will have a term due to the linear coupling between the spontaneous polarization" Could someone...

Does a rotating conductor generate an electrical potential due to charges "feeling" a centrifugal force?

Can we predict the movement of a magnet in a uniform magnetic field using Maxwell's equations? What if the magnetic field is variable, for example if we have two magnets moving in a reference frame? Thank you for any answers and I wish you a Merry Christmas! :)

Homework Statement A rotating magnetic dipole is built by two oscillating magnetic dipole moments, one along the y-axis and one along the x-axis. Find the vector potential at a point: (0, 0, ##z_0##) along the z-axis. Then find the magnetic field at ##z_0## . As the magnetic field is a function...

Homework Statement A coaxial transmission line consists of an inner cylindrical conductor of radius a = 1 mm and a cylindrical outer conductor chosen to make the characteristic impedance 75 ohm. The space between the conductors is lled with a gas which can stand a maximum eld of 105 V/m without...

Homework Statement A thick slab in the region 0 \leq z \leq a , and infinite in xy plane carries a current density \vec{J} = Jz\hat{x} . Find the magnetic field as a function of z, both inside and outside the slab. Homework Equations Ampere's Law: \oint \vec{B} \cdot d\vec{l} = \mu_0...

So General Relativity explains the force of gravity as mass/energy induced curvature of spacetime. This correctly predicts gravitational time distortion, nonlinear geodesics and gravitational lensing, the anomalous precession of planetary orbits, the schwarzchild metric, and so on. Could the...

As we know, work done by an outside agency in creating some current ''I" in an inductor 'L' is 1/2LI2. Now this result is derived by quasistatic approximation if I am not wrong. Now, I am assuming that in non quasistatic (real) scenarios, the work done by outside agency would be different(If you...

Homework Statement I'm in a class where we have to essentially learn E&M ourselves and I'm challenged by Maxwells equations. I'm studying out of Purcell's E&M. The differential form of Faradays law for Maxwells equations is curl E = -∂B/∂t Im having trouble interpreting what to make of this...

Hi there! I'm looking to create a small (max 20 foot range) radio transmitter, to direct a focused radio beam at a receiver, for the purpose of remote switching. Ideally, I would like the device to work at a relatively "exotic" frequency, as I would think there is a lot of radio noise where I...

I recently watched this Varitasium video where he explains the magnetic field due to a current carrying wire. In the video he explains how what we see and describe as the magnetic field produced by a current carrying wire is actually just a electric force caused by the an imbalance of charges...

Homework Statement Consider a coaxial cable which consists of an inner cylindrical conductor of radius R1, and a shell cylindrical conductor of radii R2 and R3. The 2 conductors are separated with a dielectric material of permittivity ε. Consider the length of the cable, ℓ, much larger than R3...

Homework Statement Consider an infinite environment with electrical permittivity non-homogeneous $$\epsilon=\epsilon_0(1+a/r)$$ a being a positive constant. A conducting sphere of radius R and charge Q is put on that environment, centered at r=0. Determine the electric field $$E$$, the...

Homework Statement A parallel plate capacitor has 2 square plates of side l, separated by a distance d (l is a lot bigger than d). Between the plates, there is a linear and non-homogeneous dielectric with constant $$\epsilon_R=1+ay$$ with $$a$$a positive constant. Calculate the electric field...

Homework Statement This is irodov's problem #310 in electrodynamics A long solenoid of cross-sectional radius a has a thin insulated wire ring tightly put on its winding; one half of the ring has the resistance ## \beta ## times that of the other half. The magnetic induction produced by the...

Hi in every theoretical explanation of any kind of DC motor there's always a split ring commutator and two brushes like in the following pic then when it comes to my motorbike/car starter motor rebuild the real thing in practice is different- see the following pic with four carbon brushes- two...

Homework Statement Are ALL parallel plate capacitors linear? Homework Equations D = permittivity * E The Attempt at a Solution Capacitance is linear if permittivity is constant. Is there a case where a parallel plate capacitor is not linear?

In class while learning about electromagnetism, I was given the following two equations: U=-μ⋅B τ=μ×B where μ=IA First of all, what does μ stand for? How should I interpret the relationship between potential energy (U) and torque? Can someone explain this in terms of μ and B?

Hello Everyone, Could anyone please explain the difference between the conduction current density (J=σE) and the convection current density (J=ρvd)? I really appreciate any examples or applications to further elaborate these two theories. Note: vd is the particles' average drift velocity...

In the classical electromagnetic field theory, the field density of energy is given by: $$u = (\epsilon/2)E^2 + (\mu/2)H^2$$ One of the differences between the classical electromagnetic theory and the real world is that in classical EM all charge and current density, (ρ(r), J(r)), is...

So I was doing some calculations last night on railguns for fun, and I got some very surprising results which seams like they must be wrong. The calculations are simple and I must have overlooked something. So we all know that F = B * I * L when all are orthogonal, a capacitor discharge is I =...

Consider the Kirkoff integral theorem and the Huygens -Fresnel principle/formula (both from Wikipedia): KIT The Kirchoff integral for monochromatic wave is: $$U({\mathbf {r}})={\frac {1}{4\pi }}\int _{S'}\left[U{\frac {\partial }{\partial {\hat {{\mathbf {n}}}}}}\left({\frac...

Maxwell stress tensor ##\bar{\bar{\mathbf{T}}}## in the static case can be used to determine the total force ##\mathbf{f}## acting on a system of charges contanined in the volume bounded by ##S## $$ \int_{S} \bar{\bar{\mathbf{T}}} \cdot \mathbf n \,\,d S=\mathbf{f}= \frac{d}{dt} \mathbf...

Hi all, (See attached image file) Two mutually coherent and collimated light beams intersect as shown, creating the stationary 'bright' and 'dark' fringes of fig.A. Suppose that, after the fringe pattern has formed, we insert a very thin (compared to the fringe-width) and (ideally) perfectly...

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...