Electromagnetism Definition and 829 Threads

A complete set of lecture notes for an upper-division electromagnetism course. The course concentrates on the derivation, properties, and uses of Maxwell's equations. Topics covered include electrostatics, dielectric and magnetic media, magnetic induction, electromagnetic energy and momentum...

Could someone please recommend a book for 2nd year Electromagnetism? The topics to be covered are: Vector calculus (div, grad, curl), electrostatics, special techniques for potentials, electric fields in matter, magnetostatics, Magnetic fields in matter, current, Ohm's law, circuits...

I've managed to derive from Maxwell's equations the homogeneous electromagnetic wave equation with respect to the magnetic field. (The one that goes Del Squared of H minus (The second order partial derivative of B multiplied by the recipricol of C squared all equal to zero) Hopefully that...

Homework Statement -------/\/\/\--------- I X X X 10 Ohm X X XI I X X X X X X X X X XI I X X X X X X X X X XAmmeter I X X X X X X X X X XI I--------il-----------I ...5V Length=10cm and width =10cm R=10 Ohms V=5 volts decreasing magnetic field at rate 150T/s (into the page) What is the...

A plasma is described by the dielectric function \epsilon (\omega) = \epsilon_0 (1-\frac{\omega_p^2}{\omega^2}) where \omega_p is a constant. Any attempt to establish a voltage V(t) = V cos \omega t across the plasma generates a region of vacuum called the "sheath" on either side...

Hi, second term is coming up, woot. I have e&m next semester and I heard that griffiths is one of the best texts around on numberable occasions, my university has it but it's not for my class but a senior class instead. I don't see why I need to use a certain textbook, I didn't for calc or...

In A. Zee's quantum field theory in a nutshell he assumes familiarity with Maxwell's lagrangian \mathcal{L} = -\frac{1}{4}F_{\mu\nu}F^{\mu\nu} where F_{\mu\nu} = \partial_\mu A_\nu - \partial_\nu A_\mu with A the vector potential. Although I've seen the magnetic vector potential, I've never...

Homework Statement The atmostspheric electric fields at heights of 100m and 1000m above the surface of the eartg are 110 v/m and 25 v/m respectively and are directed downwards. Evaluate the averge electric charge per unit volume in the atmostsphere between these heights. Express your result...

Situation A positive test charge q is moving parallel to a current-carrying wire with velocity v relative to the wire in frame S. It is assumed that the net charge on the wire is zero and that the electrons in the wire also move with velocity v in a straight line. The leftward current in the...

I read in an article that the theory of Electromagnetism makes use of Complex Numbers. How are the tools and tricks of Complex Numbers used in Electromagnetic theory. I just wanted to understand the basics of this connection of Complex Numbers and Electromagnetism and figure out if this...

Homework Statement A proton traveling at a speed of 3.0 x 10^6 m/s travels through a magnetic field of strength 3.0 x 10^-3 T, making an angle of 45 degrees with the magnetic lines of force. What force acts on the proton? Homework Equations F = QvB The Attempt at a Solution I...

I have a few questions about electromagnetism that no matter how many texts i read i can't seem to figure out, so i'll cut to the chase. 1) why is current in the opposite direction of the flow of electrons? Shouldn't it be in the same direction as the electrons are travelling? 2) How does...

Homework Statement Hi to everyone! I would like you to help me for a problem of classical electrodynamics. I have to study the relativistic motion of a charged particle in a coulombian field with center in the origin of the cartesian axes. I have to study the case in which the initial...

I need to make a project for my physics summative (gr 12); and I am leaning towards electromagnetism... since my attempt in making a generator failed - and I paid a lot for the magnet and wires. I was thinking of making http://www.bizarrelabs.com/mag2.htm That... but then I'm wondering if...

I have one question. It is about current in conductor. It is about electromagnet induction. So I move the magnet among conductor in closed circular loop, like on this http://www.imagehosting.com/show.php/710601_untitled5.bmp.html" So is the way of moving of the electrons depends from the way of...

Homework Statement In problems involving electromagnetism it is often convenient and informative to express answers in terms of a constant, x, which is a combination of the Coulomb constant, k, the charge of an electron, e, and H=h/(2pi), with h being Planck's constant. For instance, the...

Hi, I've been working on a review assignment for a while, and I"m very good at electricity, so this question has me stumped. Specifically, the 2002 AP Physics B, #3. Two lightbulbs, one rated 30 W at 120 V and another rated 40 W at 120 V, are arranged in two different circuits. (a) The...

If you place a metal ring in a region in where a magnetic field is rapidly alternating, the ring may become hot to your touch. Why? Is it because a changing magnetic field can create electric fields? I AM SO CONFUSED...and it seems so simple?!?

Homework Statement This is a question about turning effect on a current-carrying coil lying between the poles of a magnet. Please refer to the following link: http://img11.picsplace.to/img.php?file=img10/22/N1_000.gif On the textbook, it is stated the turning effect on the coil can be...

does anyone have manual solution for field and wave electromagnetic by D.K.Cheng?If you do please send me via <jafarianjelodar.ali@gmail.com> THANKS

Are there any good introductory electromagnetism books that don't cost too much? I'm interested in relativity but I would like to back up and gain a more solid foundation in electromagnetism first. I would like something modern, somewhat rigourous(mathematically), and preferably with a...

Homework Statement A particle of charge q starts from rest at the origin of coordinates in a region where there is a uniform electric field of strenth E parallel to the x-axis, and a uniform magnetic field B parallel to the z-axis. Find the equations of motion, and solve them to show that...

Homework Statement Consider a thin spherical shell having surface charge density σ, and radius a as shown in the diagram (see attachment). Find, by integration over the sphere, the potential at a point P, a distance r fromthe centre of the sphere, for r > a. Using this result also find...

Homework Statement A loop of wire of aream 0.32m^2 is palced in a 0.75 T magnetic field. The magnetic field is changed to 0.35 T in the opposite direction in 0.45 s . What is the magnitude of the current through the 15 ohm resistor. Homework Equations emf = -N (flux / time) The...

Homework Statement 1) The coil of a moving-coil loudspeaker has a mean diameter of 30mm and is wound with 800 turns.It is situated in a radial magnetic field of 0.5T. Calculate the force on the coil, in Newtons, when the current is 12mA. 2)Explain what happens when a long straight...

In electromagnetism, when there is an emf is induced in a secondary coil from a current flowing in a nearby primary coil (such as in a transformer), then how is the mutual inductance, number of turns of each coil, the current in the primary coil, and the emf in the secondary coil related...

I'm looking for something that covers similar material to Electromagnetism, Grant and Phillips (Manchester Physics Series), but is shorter and easier to read through - I find Grant and Phillips useful (and will buy it), but could really do with a summary/outline to build on. Any...

Hello, this is my first post on these forums, and I hope to get a response. I am doing an experiment about building a type of an amusement park ride on a much smaller scale, and I have some questions and need some advice. Firstly, when I make an electromagnet by wrapping a piece of metal with a...

Hi, I have a question concerning the attached diagram: The question which accompanied the diagram is: Why does the aluminium rod (the one that lies across the other two) slow down when a current is produced? The official answer is: "A current is produced in the rod which experiences a force...

How does one calculate the reflection coefficient for light at an air to silver interface at optical frequencies (\omega = {4 *10^{15} s^{-1}}) given \mu_{I} = \mu_{T} = \mu_{0} , \sigma = {6 * 10^7 mhom^{-1}}

I don't understand what is the meaning of "flux" .I just know it has some relation between eletromagnetism.Please explain what is flux to me.

This is a problem that's been puzzling me for a while now, so hopefully somebody knows the answers to some of these questions. Can an electromagnetic field cause water molecules to move? Can changes in the intensity or location of an intense electromagnetic field cause water molecules to, even...

I'm very confused Electromagnetism confuses me. In a circuit the movement of electric charges creates a magnetic force. (the type of magnetic force that is associated with magnets) Why does the movement of electric charges produce a magnetic force? The combination of a electric field...

An ion with a change of 1.6*10^-19 enters a 0.075 T magnetic field. If the ion follows a circular path of radius 0.083m, what is the momentum of the ion? I tried manipulating Fc = Fmagnet into Momentum = QBr, but that didn't work... any ideas? Thanks!

When I was a student, I remember that I disliked a lot these finger exercises. I soon realized that these were totally useless, and I solved everything without any finger rule. But since, I have forgotten how I did ! I only remember that I concentrated on currents, nothing else. Have some...

question on electromagnetism, moving electrons with respect to other electrons causes a field to be felt right? maybe if i skip to my example itl make sence... lets say you fire a bullet parallel to a wire. will the bullet feel a magnetic field, and if so, will it change its tragectory...

What are the "classical Textbooks" for quantum mechanics and electromagnetism? hi, I want to use my vacations to study quantum mechanics and eletromagnetism. Are there any "classical textbook" for these 2 subjects, like "Goldstein classical mechanics" for mechanics? Thanks, Twukwu.

Hello, I'm wondering, which force is stronger, SNF or EM, how was it proven that specific force is stronger than the other, and are there actually any cases where the weaker force is actually the stronger one. Thanks for all the help

Could someone explain the wording (and possibly see if I'm going the right way about it) of this question to me. What is the current required in the windings of a long solenoid that has 1000 turns uniformly distributed over a length of 0.400m, o produce at the centre of the solenoid a...

http://www.zen96175.zen.co.uk/question.GIF Hi everyone :-) This is my first post here! I have a question regarding electrostatics, in the picture above. I am not looking for the solution at all as this work will be assesed, I am just hoping that someone can verify/ poke me in the right...

given: the electric field at a point on the axis a distance x from the plane of a ring is E = \frac {q*x} {4*pi*E0*(x^2+r^2)^{3/2}} where E0 is the permeability coefficient The charged ring is replaced by a circular sheet of charge of radius a a surface charge density sigma. The ring...

A few more questions that i am stuck with: An AC generator has a coil area of 120cm². The coil has 100 turns. The generator produces a peak voltage of 29V when the coil is turning at 6000 revolutions per minute. Calculate the magnetic flux density (assumed uniform) required. The rate of...

The problem (From Electromagnetism by Pollack and Stump, exercise 11.34) A stationary charge of charge e and mass m encounters a electromagnetic wave with vector potential \vec{A}=\vec{j}f(x-ct) where \vec{j} is the unit vector in the y-direction. The scalar potential is zero...

I'm completely clueless with these statements. I watched a video on this, but all it said is that it was "complex" which didn't explain it much. If someone would possibly help me that would be great.. and appreciated! Thank you. A. Describe the force "felt" by the test charge as it is...

I have 3 more physics electromagnetism problems, thanks again for the help (helped tremendously in the last unit for my test). http://i2.photobucket.com/albums/y15/seiferseph/1.jpg not sure what equation to use, i can solve for change in flux using the magnetic field and area, but not sure...

I have three multiple choice questions on electromagnetism that i have been unable to get. The answers are there, i just can't get them. http://i2.photobucket.com/albums/y15/seiferseph/1.jpg i can't find any equation to use that doesn't have more than two unknowns. I've tried Fb =...

hi, I built a crane using hydraulics to move the arm and using an electromagnet at the end of the arm to pick up and move metal objects... what other applications could use hydraulics and electromagnets?

Electromagnetism -- induced EMF Please help :) I'm just trying to grasp the whole ... induced EMF concept ... please, anyone?! Also ... breaking the field lines?

Hi, Are there ways to use/reduce electromagnetic theory to understand circuit theory better? ie use circuit theory as a special case of em theory? if so can you suggest books which do it this way? basically my idea is to look at any circuit from the general point of view - using the physics of...

Sorry if this has been asked before, I searched but didn't find anything What's the difference between EM radiation (photons) and EM fields? When an antenna is emitting a signal at X Hz, is it emitting photons with the frequency of X Hz or is it just making electrical and magnetical fields...