# electromagnetics

1. ### How to find the Braking Torque of an Eddy Current Braking Setup?

Homework Statement: Finding the braking torque applied on a moving disk as a result of the Eddy Currents Homework Equations: $$F = \sigma v V B^2$$ So right, Basically my problem is how to find the torque exerted by an eddy current braking setup. My setup consists of a disk rotating on an...
2. ### I How to measure electric and magnetic fields in asymmetric capacitors?

Summary: I need to build an asymmetric capacitor, but the mathematics of electromagnetics become too tough, do you have any info that can help? Appreciate it!!! Hello, I am an undergraduate student in engineering and I want to build an asymmetric capacitor, so I need electromagnetics which I...
3. ### E-field generated by constant current in a circular loop

1. Homework Statement Discussions of the possibility of a tangential E-field external to a current-carrying conductor must include a voltage source and a return path. Here the problem is reduced to (we believe) the simplest possible geometry. Assume that a circular conducting loop has constant...
4. ### What is this error in Maxwell Ansys -- 'Transient solver handles only isotropic conductivity!'

Hi, I am working on Maxwell version 17. I have a simple motor to analysis 2D FEM. However, when I analyze the model, I see this error. "Maxwell2d solver, process solver2d error: Internal Solver Error: 'Transient solver handles only isotropic conductivity!'. (7:07:10 PM Apr 16, 2018)" I am...
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### I Induction via Infinite sheet of Current

My thoughts are concerning an infinite sheet carrying current in a direction. I wish to induce a unidirectional electric field outside of the sheet via induction. My ideas were that if the current was changed linearly in a sawtooth fashion, then I would achieve the induced electric field in...
6. ### [Electromagnetics] E-Fields & Equipotential Surfaces

1. Homework Statement This is from the book Engineering Electromagnetics by Hayt & Buck. 2. Homework Equations E = - (ΔV/ΔL) 3. 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...
7. ### Voltage across switch in LR circuit as switch is opened?

1. I thought that when switch was closed, voltage at the right side of switch was 0 and long time after the switch is open, the voltage at the right side of the switch becomes 0. 2. After the switch is open ecause of the inductor, voltage at the right side of the switch is εL = induced emf So...
8. ### How to calculate the Electric Field due to Capacitors?

I have a problem that I have encountered during research. The setup for this scenario is that I am placing two contacts on top of a piece of diamond. What I need to be able to do is calculate the Electric Field at a point within the diamond when I apply a voltage to the contact. The point of...
9. ### EI Core electromagnet questions

Hello. I am trying to design an EI-core electromagnet (think two c-shaped cores with their gaps abutting). The coils would go on the top and bottom legs of the E (legs B and C in my sketch). There is a sketchbelow and you can find one here...
10. ### Electromagnetics: Plane Wave Propagation, Unknown Medium

1. Homework Statement Based on wave attenuation and reflection measurements conducted at 1MHz, it was determined that the intrinsic impedance of a certain medium is , and the skin depth is 2m. Determine: a) The conductivity of the medium b) The wavelength in the medium c) The phase velocity...
11. ### Current flowing through a loop due to an infinite wire

1. Homework Statement An infinitely long wire carrying a 1 A current in the positive x direction is placed along the x-axis in the vicinity of a 5-turn circular loop located in the x-y plane as shown in the figure. If the magnetic field at the center of the loop is 0, what is the direction and...
12. ### Classical Cheng's or Lorrain/Corson's Electromagnetics book?

Hello, I want a book on electromagnetics for my second course on electromagnetism. In my first course we used Griffith's "Introduction to Electrodynamics" with supplements like Morin and Purcell's "Electricity and Magnetism". I borrowed those from the university's library but now I want to step...
13. ### Calculating electrostatic potential energy

1. Homework Statement Consider potential field V(ρ, φ, z) = V_0/ρ in free space and cylindrical coordinates. Calculate electrostatic potential energy stored in half cylindrical shell defined by a≤ρ≤b, 0≤φ≤π and 0≤z≤h. 2. Homework Equations W_E=½∫∫∫ρ_vVdV 3. The Attempt at a Solution I have...
14. ### Classical What best book for Electrodynamics/electromagnetics?

Need a book to completely revise ED. Book not be of beginner level. Must be of Masters level. Thanks Attaching a list of topics that needs to be there in it. Electrostatics: Gauss’s law and its applications, Laplace and Poisson equations, boundary value problems. Magnetostatics: Biot-Savart...
15. ### DC generator wiring basics

Given a simple DC generator with a single loop in the presence of a magnetic field such as the one below, typically, the analysis involves how each rectangular loop's terminal ends up on opposite sides of an armature housing each of the coils. The analysis is fairly straightforward to then...
16. ### Curl of the vector potential produced by a solenoid

1. Homework Statement / 2. Homework Equations I was looking at Example 5.12 in Griffiths (http://screencast.com/t/gGrZEPBpk0) and I can't manage to work out how to verify that the curl of the vector potential, A, is equal to the magnetic field, B. I believe my problem lies in confusion about...
17. ### Electric Potential due to two charges

1. Homework Statement Two point charges are placed on a horizontal line, the first is +3.0-μC located at x = 0.0-m, y = 0.0-m and the second is -4.0-μC located at x = 2.0-m, y = 0.0-m. At what points on the horizontal line y = 0.0 will the electric potential be zero? 2. Homework Equations...
18. ### Motional EMF: Minus sign

I'm trying to understand how electric generators work on a very basic level. I understand the heart of this is the application of the Lorentz force on a conductor moving at a velocity $v$ in the presence of a magnetic field $B$. I also understand how it can be shown that the emf is equal to...
19. ### Electric/Magnetic vicious cycle

Apologies for the melodramatic title. In studying AC current distribution in cables (skin effect), one can view the AC current as producing a time varying magnetic field in phase with the current itself (Ampere's Law). This in turn creates an electromotive force 90 out of phase with the current...
20. ### Capacitor with magnetic dielectric

Odd question, would anybody know what would happen if a parallel plate capacitor (good conductor) had a soft magnetic material (fairly poor conductor) as a dielectric? What would be the DC/AC electrical characteristics of this?
21. ### Refraction Index problem

1. Homework Statement Unpolarized light hits a flat glass surface, 37.5 degrees to the surface's normal. The reflected light's polarization is investigated with a polaroid. The relationship between the max and min value of intensity from the polaroid when it is rotated is 4.0. What is the index...