Electromagnetism Definition and 830 Threads

Can anyone please explain the concepts of scalar and vector potential and how they can be used to derive the wave equation for light? References are welcome. Thanks in advance for any help!

I am struggling to understand the relationship between electromagnetism, electromagnetic fields and electromagnetic radiation. I understand that a moving electric charge creates a magnetic field and a moving magnetic field creates an electric charge and that this is the foundation of...

Hi everyone, I have been given an assignment with my physics subject and describe in 400 words how electromagnetism can be used to determine the composition of different chemical mixtures I was hoping someone could lead me to a couple of websites to do my research. I have entered about...

Hey I am studying electromagnetism at the moment and one problem I'm having is the energy density. Instead of typing everything out, this pdf has everything. http://www.physics.sfsu.edu/~lea/courses/ugrad/360notes11.pdf There are some things I don't understand. Why is the surface integral 0...

Hi. Sorry my spelling, because I am not English. Homework Statement In a sphere truncated sector with an angle of 60 degrees, there is a uniform charge distribution, \rho. Calculate the electric field in (0,0,0). The sector starts in z=a and ends in z = b. The sphere center is in (0,0,0)...

Homework Statement A sample of two different irons, Fe2+ and Fe3+, are accelerated by the same potential and then sent through the uniform magnetic field of a mass spectrometer. a) Which ion moves faster after being accelerated? Justify your answer by referring to equations used in this lesson...

Homework Statement Calculate the length l of an an iron-free cylindrical coil if it has 9400 turns (N), a thickness of 0.6cm and an inductance L = 68 mH. Take magnetic field constant \muo = 4\pi x 10-7 Wb/Am (a) l = 63mm (b) l = 54mm (c) l = 46mm (d) l = 36mmHomework Equations L = N2 \muo...

Homework Statement A hoop of radius R and total charge -q is oriented with its normal vector along the z-axis. A positive charge +q is placed at the centre of the hoop. The potential at a distance r along the z-axis is: V(r) = (\frac{q}{4\pi\epsilon_0}(\frac{1}{r} - \frac{1}{\sqrt{r^2 +...

Hello, I want to know the right answers to these questions. I will try to state my answers but I want to know if they are right or wrong. Thanks. Homework Statement 1.Does the Sun's mass decrease due to its radiating electromagnetic waves? 2.Does the speed of a light beam change as it...

what is the best book that you know that provides explanations of electromagnetism and its phenomena without too much hard maths please?

Hello, I'm currently taking an upper level undergraduate Electromagnetism class and having some difficulty learning the concepts. We are using Griffith's edition and I must say I'm not a fan of the book, so I was wondering if anyone has any other books they could recommend, or even videos...

Given a propagating field expressed as E = Em Sin (wt - bz)j in free space, find the displacement (D) and the magnetic field (B) created by this electric field using a relevant maxwell's equation. note : w is in fact omega and b is beta. j is a unit vector. I don't know how I'm meant...

i am looking for an interesting book that explains electromagnetism and the actual science behind it and how it works. i do not know much about this subject so the book can't be to complicated.

A magnetic monopole, if it existed, would produce a magnetic field B = gr/r^3, where g is the magnetic charge, and r is the distance from the monopole. Calculate the angular momentum of a system consisting of a monopole g and a charge e, both at rest. The attempt at a solution I know...

Homework Statement If the charge density increases linearly with distance from origin such that pv=0 at the origin and pv=10 C/m^3 at R=2, find the corresponding variation of D. So we know that for R=0, pv = 0 and for R=2, pv=10 C/m^3. We know that the charge density increases linearly from...

Here are two hypothetical experiments to illustrate my confusion... #1 Two wires are positioned parallel to each other. A current is applied to both wires in the same direction. I would expect the 2 currents to each generate a magnetic field and that the 2 fields would interact to produce a...

While light's photon is manifested where's the photon in electromagnetic radiation? Does it show up in some materials? Thanks

Homework Statement Two rods, of lengths l1 and l2, have charges q1 and q2 a)Find the charges per unit length for each rod individually. b)Find the charge per unit length, averaged over both rods. c)Check your result for l1 approaching 0 d)Check your result for l1=l2 Homework...

If observer A was at rest with respect to a charge that was moving with a constant velocity |v| > 0 in observer B's reference frame, would observer A detect a magnetic field?

Hi everyone, I'm trying to solve this prac design, but still don't know what to do, can anyone please give me some suggestions? You are given an old cardboard box from Faraday’s, the bargain supermarket for electrical enthusiasts (“Everyday Low Charges”). The box contains  a battery, ...

Homework Statement We are given surface current density, K which is constant (K is negative) along the z-axis which is placed in x=a plane (the board which contains this density is neutral), in x=0 plane there's an infinite plane which is charged by a surface density \sigma which is constant...

May a magnetic field exist w/o electricity? Yes, as lodestone shows us but where is the electricity? Electricity generates magnetism with it. So where is the electricity with lodestone?

Hi, I'm looking for the best book in which I can learn very well electromagnetism. I have good notions of all mathematics till differential equations. Furthermore I basically know analytical mechanics (I have studied on the Landau's Mechanics) and special theory of relativity. Thanks in...

A stone is moving constantly in a horizontal motion in a uniform magnetic field in the direction pointing into the page. The field's strength is 1.7T. How fast does the stone have to move in order for it to remain moving horizontally without any vertical deviation? For this quesion, using...

Homework Statement A 20 turn wire that has a surface of 400cm^2 is rotating around an axe and is at a right angle to a uniform magnetic field of 0.3T. Find the average magnetic field induced if the speed of the rotation is 10 rotations/second. Homework Equations Faraday's Law...

In a particle physics formalism, electromagnetism can be described in terms of interchange of virtual photons. The range is then c.t = hbar / E with t the lifetime, and E the energy of the virtual particle. What is the argument then, for long range EM interactions, in terms of E? Is it...

1. A particle of charge q=6E-6C and mass m=1E-10kg is fired out of a charge gun towards the uniform magnetic field pointing into the page, B=0.50T. The particle moves vertically up originally and then accelerated through potential difference of 200V. There is a diagram of the B field going...

We know that a lot of electrical components associations are calculated using the harmonic average. If we have parallel resistors we use the harmonic average. If we have serial capacitors we use the harmonic average too and so on... But my question is: why the harmonic average? what does...

Ouch, had just written a big post when my university internet connection timed out on posting, so I'll keep this one short but powerful: I came to the understanding E and B fields are modified when changing reference frames. But what about the following situation: Charge q (named 1) is...

Homework Statement Assume that Earth’s magnetic field is everywhere perpendicular to the path of a proton and that Earth’s magnetic field has an intensity of 4.07 × 10−8 T. What speed would a proton need to achieve in order to circle Earth 1660.0 km above the magnetic equator? Answer...

Homework Statement These are some general questions I have, related to an old assignment I am looking at. 1) Discuss the applications of polarisation in: a. radio transmission across water b. broadcast TV transmission c. satellite communication 2) Explain why a plane electromagnetic...

Quick Question(s): Who was it that tried to account for the EM force in terms of spatial curvature; i.e., who tried to expand GR in order to explain EM attraction and repulsion? Also, on what grounds was his account refuted?

What's the difference between "repulsion force carrier and attraction force Carrier" in electromagnetism interactions? We know that these two messenger photons should be distinguished. But in what features and details?

Q1) The amplitude of an electromagnetic wave is E0 = 471.0 V/m. Find the following values. (a) Erms 333.047 V/m (b) Brms __ nT (c) the intensity I __W/m2 (d) the radiation pressure Pr __nPa Q2)(a) For a given distance from a radiating electric dipole, at what angle (expressed...

Hey there! I was just listening to Richard Feynman on the way home and hit yet another issue I have with relativity... I'd be most thankful for any input! :) So, suppose we got two charged particles moving parallel to each other. A charged particle has an electrical field - if it's moving...

Hey everyone, I just wanted to double check some solutions and inquire about a problem. Homework Statement A toroid is a coil of wire wrapped around a doughnut-shaped ring (a torus). For a tightly wrapped toroid with N turns, the magnetic field lines of \vec{B} form concentric circles...

Homework Statement You are informed that the charge density is: $\rho \left( r \right)=k{{r}^{-n}},r<a$, where k is a constant and n is a whole number. Determine n. Homework Equations Besides that, I know that: \[E=\frac{Q}{4\pi {{\varepsilon }_{0}}}\frac{1}{{{r}^{2}}},r<a\] (E is...

Programmer-turned-amateur-physicist here. I'm reading Feynman's lectures, but I'm urged to do some physical experiments. The thing is, I have no idea about the practical side of things. Could someone write me a detailed description of some experiment? Say, the one with the hanging wire and the...

Four resistors are connected to a battery as shown in the figure. The current in the battery is I, the battery emf is emf, and the resistor values are R1 = R, R2 = 2R, R3 = 4R, and R4 = 3R. Picture: http://www.webassign.net/serpop/p21-32.gif (a) Rank the resistors according to the...

In studying the world, physicists found that, in order to completely understand what today we call "Electromagnetism", it was necessary to do three things: find an equation which describes the electric field under all circumstances, find an equation which describes the magnetic field under all...

I need help designing some build-from-scratch DC motors. I'm looking to build really robust motors that I can be be sure will demonstrate clearly the principles involved, but that can be modified by my boys and that they can really *play* with and use to run simple toys. I've already shown...

Hello to everyone. I'm quite new here and I just wish I have found this site sooner. I am currently enrolled in Physics 2 class (Introductory) and we have just started Electromagnetism. Quite frankly, I am here to ask for some guidance as I am very weak in Physics. The only reason I passed...

Have exam tomorrow. I know I should have studied before and more, but please help. If you know the answer, please take some time to reply. Thanks very much. Homework Statement There are two charges, q1 = +4.5nC, and q2, ?, which are at distances d1 = 2.5cm and d2 = 2.0cm, from a point...

Can anyone please answer, and if possible, explain, this question? Thanks 1. A battery is connected between A and B of a bar made of semi-conductor of type P. The positive electrode was connected in A and the negative in B. What's the current direction? A. from A to B B. in the semiconductor...

Homework Statement the electric potential of some configuration of charge is given by the expression: V(r)= (Ae^(-pr))/(r) where A and p are constants. Find the E-field E(r), the charge density rho(r) and total charge Q. The answer for rho is given in book as: epsilon-not * A *...

Homework Statement Two very long thin wires carrying equal and opposite currents of 103 A are placed parallel to the x-axis at y=0 and z=+-0.5. Calculte the magnetic field B in the x-y plane and determine it's maximum gradient.Homework Equations I'm having serious trouble understanding the...

Homework Statement please visit this site and solve with calculations, Thank you! http://rapidshare.com/files/338079894/Figure_it_out.doc Homework Equations V=IR Rt=1/R1+1/R2+1/R3 The Attempt at a Solution Please solve this circuit Thank You

With a set coil if you increase the electric flow does the flux density increase And/or the magentic field decrease/ maintain/ increase in size..? Thanks once again, Sem.

Hi. I've been learning how to use geometric algebra and I've been stumbling when I apply it to E&M. I am hoping someone here can point out what I am doing wrong. The problem comes when trying to represent the field tensor in terms of the 4-potential. Here is the standard form: F^{\mu\nu}...

I got this question on an Assigment, and ..man, am having really hard time with it Here is how it start : "A student used the apparatus shown below to measure the radius of the curvature of the path of electrons as they pass through a magnetic field that is perpendicular to their path. This...