E&m — 231 discussions

Homework Statement Imagine a square in the xy plane with each side of length a. It has a uniform charger per unit area (σ). The center of that square is at the origin. Determine the electric field at a distance z above the center. Homework Equations E=k integral{(sigma/r^2) * r * dA}...

Homework Statement We have a line charge of density λ and length 2L along the x axis. What is the electric field at the point (0,1,1)m for L=1cm and λ=200μC/m? (Hint: no new integral is required.)Homework Equations E=(kq)r^2The Attempt at a Solution I drew a figure and noticed that the...

I'm taking junior level E&M this semester and we are using Foundations of Electromagnetic Theory by Reitz. I have previewed the book and it seems a little on the less thorough side while also requiring much prior knowledge of the subject. Are there any other texts which I could supplement with...

Hello, Well, actually it's not a homework problem, I just got really confused about bound charges. Originally, I thought it was just a special technique to do the integral, but somehow Griffiths suggest that bound charges are phsically exist.(chap. 4.2.2) Well, I can accept his argument...

I am a junior in AP Physics (Mechanics). At my school, there are about forty seniors and two juniors in AP Physics C Mechanics and two seniors in AP Physics C E&M. The other junior isn't doing to well in mechanics; he is signed up for E&M but my teacher is trying to dissuade him. During my...

Hello, I was wondering if anyone has heard of or seen any work done into looking for what would be the analogue of stress in General Rel. for E&M. I am not talking about actual stress but the analogue to it. In the flat space metric with perturbations, linearized gravity begins to have...

I've seen in textbooks before, there if there were monopoles, Maxwell's equations would look more "symmetric" between the E and B fields. Such that (in cgs units): \begin{align*} \nabla \cdot \mathbf{E} &= 4 \pi \rho_e \\ \nabla \cdot \mathbf{B} &= 4 \pi \rho_m \\ -\nabla \times...

Has anyone had any experience with a graduate E&M class that didn't use Jackson? Is Jackson necessary? I have it at home and it's a very difficult read and the problems are impossible. I have other E&M books and I can actually learn E&M from them. My grad E&M class (master's program)...

I am missing something very simple... in my book, it gives, for capacitors in series, that: 1/C(eq) = 1/C(1) + 1/C(2) using numbers, it says... 1/C(eq) = 1/6.0 uF + 1/3.0 uF ... C(eq) = 2.0 uF I cannot figure out how they got C(eq) = 2.0 uF Thanks

I've seen on most books and in class that Gauss's law is usually stated like \oint \vec{E} \cdot d\vec{A} = \frac{q_{en}}{\epsilon_0} Shouldn't the integral be a surface integral rather than a line integral? I've seen times in problem resolution where they evaluate the integral as a...

Hi I want to take a year long QM squence at my school but the prereqs is a year long sequence in E&M. I was wondering what skills are picked up from E&M that is used in QM. I have taken modern physics which had light exposure to QM and I did not see much drawn from what little E&M i know...

Hi. :) I'm looking for exam questions or exercises on Electricity & Magnetism (with solution if possible). The level should be *roughly* equivalent to the exercises in Purcell, Electricity & Magnetism, Berkeley Physics Course (usually 2nd year at university) in content. I've googled already...

I have been studied to Purcell's book. And, this semester finished so I'm finding another book. Professor recommanded me the Jackson's book. Which one will be better?

Homework Statement Please see the attached pdf file, which is the bottom of page 365 from the 3rd edition of the book. This is a lesson about (generalized) waves, and f(z,t) is the vertical displacement of the medium at point z, time t. F is net force and T is the tension on the string in the...

Hello, Im struggling with a pretty horrendous lecturer for this 2nd year course, so am trying to learn a lot of it myself with a decent textbook. I am getting pretty scared for the exam in summer. We have been reccomended Jewett & Serway, but its kinda just a general physics, and doesn't seem...

Homework Statement Show that the electric field of a "pure" dipole can be written in the coordinate-free form E_{dip}(r)=\frac{1}{4\pi\epsilon_0}\frac{1}{r^3}[3(\vec p\cdot \hat r)\hat r-\vec p]. Homework Equations Starting from E_{dip}(r)=\frac{p}{4\pi\epsilon_0r^3}(2\cos \hat r+\sin\theta...

Homework Statement sigh* Well, I have more than a week to do this lab, and usually I don't resort for help here, but on this lab there are so many things I am unsure of. So here's the setup of the lab: I have a one Farad capacitor, a DC power supply, a multimeter, a bunch of...

I want to study electromagnetism, but my math background is only calc I (working on calc II right now). Is there a good textbook on E&M that is appropriate for my background? 'Physics for scientists and engineers' by Serway was recommended but I'd like to cross-check with the community. Or...

Hi there. I managed to get in a car accident before all of my summer exams so now have to take them all in September. I have started revising and I have a question which I cannot do. A thin, circular disk of dialectic of radius 'a' carries a uniform positive sheet charge density of...

It has been awhile since my multivariable calculus course. I do not want to review everything before tackling these texts, just the important stuff. What concepts and theorems are most important? Anything from linear algebra I should review? Thanks.

Does anyone know of a good textbook with challenging problems for Intermediate E&M? The one we are using in my class is "Introduction to Electrodynamics" 3rd ed. by Griffiths. I looked at the problems in the book, and they don't seem to be hard enough. I'm not really looking for problems that...

So I got a question on a E&M Midterm: There is a line current of I at the origin going in the Z direction. There is a magnetic dipole of: \vec{m}=m_r\hat{r}+m_\varphi\hat{\varphi} located at (r,\varphi). What is the force and torque on this magnetic dipole? So I used the equations...

I am making a webpage on self-study references for cosmology, relativity, quantum mechanics, elementary particles and quantum field theory, and string theory. I need suggestions for background references. Suppose someone who was/is an above average (but not top) student has taken first-year...

Homework Statement Suppose that the magnetic field in some region has the form B=kz\hat{x} (k constant). Find the force on a square loop (side a) , lying in the yz plane and centered at origin if it carries current I flowing counterclockwise, when you look down the x-axis. Homework...

Okay so I calmed down from my last post and am ready to actually do something worthwhile. Would I be able to start self studying material for a future class that doesn't rely on the second half of a mechanics course? Specifically I'd like to start studying some Intro E&M stuff on my own, is...

A general problem you run into during an E&M class is the one involving a point charge a distance from a charged sphere. In cases where the point is far enough away from the sphere, the system can be treated like two points. In my case I have a point charge "q" a distance "z" away from the...

This fall will be my first semester at a university. I have a pretty easy schedule in HS so I'm studying the Feynman lectures and working Irodov's problems. Since the university doesn't give credit for University Physics I&II (Mechanics and E&M) for the AP Physics C exams, I'm planning to test...

This is not a question of 'how' to do a problem; I know the answer to it and would like an explanation of why this is the correct answer, if possible! Thanks in advance! Suppose there exists another universe where the laws of electrostatics and special relativity and the relevant physical...

Homework Statement Find out the condition for two-plane-wave interference. The two plane waves are given as \vec{E}_1 = E_0\vec{A}\exp(ikz - i\omega t) + c.c. \vec{E}_2 = E_0\vec{B}\exp(ikz - i\omega t + i\phi) + c.c. where \vec{A} and \vec{B} are complex. All other...

Hi guys, first time poster. Currently I'm going to the university of chicago and signed up to be a physics major. I've already made it through my first year--so far I've taken classical mechanics, Intro to E&M, intro to waves, light, & Optics, and I'm almost done this year with "Modern Physics,"...

Hello everyone, I made a similar post to this last semester when I went onto take my Introduction to Mechanics (1st semester of College Physics) course and asked for some books that will give me some insight to supplement the first few sections of the Halliday and Resnick (1-15, 8th edition)...

Equation sheet limited to twenty equations spanning material from electrostatics to mutual induction. Halliday Resnick chapters 21-31. 2 hours. Seems like some questions depended on you having the equation accessible, which is a matter of chance. Core exams were usually 12 MC and 3-4...

Hello again everyone. I have yet another question: this semester, I'm a tad behind in terms of math. This semester I'm finishing precalculus and next semester is calculus I. Given that I can't start any physics courses until I've cleared calculus I (and no, taking calculus I and physics at them...

Hello: A thin nonconducting uniformly charged spherical shell of radius R has total positive charge of Q. A small circular plus is remoced from the surface. What are the magtnitude and direction of E at the center of the hole? So this shell has a hole now. Can I just treat this as a...

Homework Statement A particle of charge 5.03 nC is placed at the origin of an xy-coordinate system A second particle of charge -2.00 nC is placed on the positive x-axis at x = 4.04 cm. A third particle, of charge 6.01 nC is now placed at the point x = 4.04 cm, y = 3.00 cm. Find...

This is a review I wrote for a text-book on Amazon but it really applies to all the E&M books I have seen. I put it here in case its useful to a student struggling with E&M. This book is typical of most E&M textbooks on a purely theoretical level. They present E&M as a collection of symbols...

Homework Statement Calculate the power transported down the cables of Example 7.13 assuming the two conductors are held at potential difference V and carry current I. The cable in example 7.13 is "a long coaxial cable" with inner radius a and outer radius b. Homework Equations...

Homework Statement This question refers to Griffiths E and M book. Of course I am stuck with the integral. I chose z to be in the same direction as the polarization. The integral is then P \int d\Omega r'^2 dr'\frac{\left(\mathbf{r} -\mathbf{r'}\right)\cdot...

Homework Statement This question refers to Griffiths E and M book. See the solution here http://www.physics.gatech.edu/academics/Classes/fall2005/3122/hw9solution.pdf I don't understand why they say the torque we exert is clockwise (I assume that means in the minus z direction). Homework...

Homework Statement This question refers to Griffiths E and M book. To finish the problem, I just need to show that \frac{d}{dt}\int_V \vec{r} \rho d\tau = \int_V \vec{r} \frac{\partial \rho}{\partial t} d\tau When you apply the product rule to the integral, why do you get \frac{\partial...

Homework Statement This question refers to Griffiths E and M book. I am confused about what the answer should be in terms of. Usually he gives us all constants that might be needed in the answer. But we need to know that distance between the plates here don't we? Homework Equations...

Homework Statement Two flexible but not extensible strings with linear charge density s and length L are attached to two insulating balls a distance D apart, where D<L. What do the strings look like when the system is at equilibrium? Homework Equations The Attempt at a Solution...

The magnetic field inm the gap of the toroidal permanent magnet is 0.50 T. The length of the magnetic circuit is 20 cm and that of the gap is 1.0 cm. what are the magnitudes of i) B in the material ii) H in the gap iii) H in the material iv) M in the material The Attempt at a Solution...

Prove that in a magnetic mirror the flux encircled by the orbit of the particles is conserved when the magnetic field varies. How do you do this? i have no idea how to approach/start this!

E&M Electric Fields (Harmonic Motion?) This problem comes out of "Physics (for scientists and engineers w/ modern physics) Volume 2 7th Edition" by Serway/Jewett Review Problem Two identical particles, each having charge +q, are fixed in space and separated by a distance d. A third particle...

is it a plausible thing? I'm sure it's possible because almost anything is possible, the question is it wise? an example of my hesitation to study something before it's prerequisites is that i don't want to study QM before studying hamiltonian and lagranian mechanics. should i be worried about...

The method of images exploits the fact any linear combination of solutions to a differential equation is also a solution, and the fields and potentials from a point source satisfy all relevant diff eq's, assuming the boundary conditions are met. However, a scalar multiple of any solution is...

Do you need to be very good at introductory mechanics to do well in introductory E&M? Or can you still do good in E&M (get an A) if you are not very good at introductory mechanics? To prepare for intro E&M should I do (A) review intro mechanics or (B) start studying E&M from a book like serway...

I'm trying to solve a problem in E&M, and I got an equation which depends on p and q, which I can solve provided I can write sinh(\sqrt{p^2 + k^2} \pi) as a product of a function of p, with a function of k. If I can do that, I can solve the problem, but I don't know how to do that part (or if...

Homework Statement In the case of total internal reflection, show that the average rate of energy transport across the boundary is zero. Homework Equations None Provided The Attempt at a Solution All that I have come to is that I should use some form of the following method to find...