Electromagnetics Definition and 152 Threads

Electromagnetism is a branch of physics involving the study of the electromagnetic force, a type of physical interaction that occurs between electrically charged particles. The electromagnetic force is carried by electromagnetic fields composed of electric fields and magnetic fields, and it is responsible for electromagnetic radiation such as light. It is one of the four fundamental interactions (commonly called forces) in nature, together with the strong interaction, the weak interaction, and gravitation. At high energy, the weak force and electromagnetic force are unified as a single electroweak force.

Electromagnetic phenomena are defined in terms of the electromagnetic force, sometimes called the Lorentz force, which includes both electricity and magnetism as different manifestations of the same phenomenon. The electromagnetic force plays a major role in determining the internal properties of most objects encountered in daily life. The electromagnetic attraction between atomic nuclei and their orbital electrons holds atoms together. Electromagnetic forces are responsible for the chemical bonds between atoms which create molecules, and intermolecular forces. The electromagnetic force governs all chemical processes, which arise from interactions between the electrons of neighboring atoms. Electromagnetism is very widely used in modern technology, and electromagnetic theory is the basis of electric power engineering and electronics including digital technology.
There are numerous mathematical descriptions of the electromagnetic field. Most prominently, Maxwell's equations describe how electric and magnetic fields are generated and altered by each other and by charges and currents.
The theoretical implications of electromagnetism, particularly the establishment of the speed of light based on properties of the "medium" of propagation (permeability and permittivity), led to the development of special relativity by Albert Einstein in 1905.

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  1. darida

    Electromagnetics in Spherical Symmetric Problem

    In a spherical symmetric problem the only nonzero components of the electric and the magnetic field are Er and Br Why?
  2. P

    Calculating electrostatic potential energy

    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. Homework Equations W_E=½∫∫∫ρ_vVdV The Attempt at a Solution I have no idea...
  3. Prins

    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...
  4. L

    Why are DC generator loops wired in a non-traditional manner?

    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...
  5. P

    Curl of the vector potential produced by a solenoid

    Homework Statement / Homework Equations[/B] 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 how...
  6. Mnemonic

    Electric Potential due to two charges

    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? Homework Equations V(r)=kq/r...
  7. A

    Electromagnetics radars and antennas

    What are the best universities in the world offering ms programs in applied electromagnetics, radars and Antennas.
  8. L

    Why is the negative sign in the equation for motional EMF often discarded?

    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...
  9. S

    Electromagnetics: Reducing inductance of a wire loop

    Given a flexible wire loop of a certain perimeter and planar shape, what are some good ideas to minimise the loop's inductance? For example, would it work if i surrounded the wire loop with a superconducting loop in the same plane?
  10. Dorian Black

    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...
  11. S

    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?
  12. S

    What is the index of refraction of the glass in this reflection problem?

    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 of...
  13. D

    MHB Analyzing Electromagnetic Forces in a Two-Sphere System with Insulating Fiber

    the two small plastic spheres are arranged so that they can slide freely along the insulating fiber. Each has a mass of 0.1g. The spheres are given identical positive charges. a. If the lower sphere is resting against the lower knot while the upper sphere moves to a location 6 cm distant from...
  14. D

    Computational How to learn Computational electromagnetics?

    I'm a junior majoring in EE and learned with 1. D.K cheng : Field and wave electromagnetics 2. Zill Cullen : Advanced Engineering Mathematics (differential Eqs. & complex analysis) 3. Gilbert Strang : Linear Algebra and its Applications +I've extremely avoided '~programming' course, so have...
  15. Alxb577

    Electromagnetics Essay Topic Ideas

    Hi Everyone, I need to write an essay for my electromagnetism class and i was wondering if anyone has good topic ideas. My criteria is that it needs to be 10 pages and I would like something that is interesting for me to research and write about. I was thinking so far of magnetic levitation...
  16. S

    Mass and Electromagnetics, someone please shed light

    Okay so I've recently found an insane interest in physics and am becoming familiar with simple things. However the vast amount of knowledge I have not yet acquired is pretty troubling me with understanding other things. I understand that gravity is a field influenced by a mass of an...
  17. A

    Electromagnetics - finding wavelength from e_r and f

    Homework Statement A transmission line is 1 meter and has a relative dielectric constant of 2.25 Find the phase velocity u and the wavelength λ for a frequency of 50 MHz. Homework Equations λ=?(ε_r, f) u=λf The Attempt at a Solution I am unable to get from the relative...
  18. S

    ElectroMagnetics Lenz's law vs F=qv X B

    Hello and thank you in advanced for looking at this. I have trying to come to terms with two seemingly contradictory ideas in electro-magnetics. Lenze's law and Eddie currents seem to contradict the fundamental equation F = qv X B where F is the force exerted on a particle with charge q and...
  19. J

    Electromagnetics question for physicists/engineers

    I've been looking into electromagnet design and there is a certain principle/set of equations that are bothering me... (1) B = (kμ0Ni)/L (2) ø = BA Where; - ø = total magnetic flux (wb) - B = magnetic flux density (wb/m2) I am trying to solve for an optimum cross sectional area of...
  20. baby_1

    Electromagnetics density of Toroid

    Hello I have some problems to obtaining Electromagnetic density via Ampere's Law. http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/indtor.html my problem is why we don't calculate and sum Inflow and outflow of Ampere's closed loop path.to clearing my question please take a look at below...
  21. L

    Simple fundemental Electromagnetics question

    I'm just trying to get my head around electromagnetics for the first time, and need help understanding a question that asks: "Using BH curves find the maximum permeability of the cast iron forming the magnetic path." Now from wikipedia I know that the permeability of cast iron should be...
  22. JasonHathaway

    Electromagnetics charge distribution

    Homework Statement In fact, there are two problems, and I want to know whether my solutions are right or not. 1- Two charged line with density of 15 n c/m along the x and y axes (x\pm\infty, y\pm\infty), Find the Electric field at: (a) (0,0,4) (b) (0,5,4). 2- A cylinder with radius \rho=8cm...
  23. A

    Application of wavelets in computational electromagnetics

    Hello everyone, I am a first year graduate student, wavelets is one of the courses that I am taking presently. As part of the course, I plan to explore application of wavelets in computational electromagnetics (CEM). The idea behind it is to study a few applications where wavelets are used in...
  24. M

    Schools How different is electromagnetics in grad school?

    Hello, I have been studying electromagnetics ever since I can remember. In school we did algebra electromagnetism. In 1st year college we did electromagnetism but with basic calculus. Then electromagnetics with vector calculus which in my opinion was far more involving than the previous 2. I...
  25. rizwanibn

    Electromagnetics: Vector analysis

    IItsHi.I have a problem that i am trying to solve.The complete question is shown in the image: In this question i solved the (a) and (b) part.But i did'nt understand the (c) part.Can you please explain?Thank you.(Note:The answers is given beneath the question)
  26. bhanesh

    Why Does j.ds Have Closed Integral on Electromagnetics Equation?

    Why j.ds has ' closed integral ' on below equation
  27. Y

    Archived Electromagnetics field question

    Homework Statement The figure shows two very large slabs of metal that are parallel and distance l apart. Each slab has a total surface area (top + bottom) A. The thickness of each slab is so small in comparison to its lateral dimenstions that the surface area around the sides is negligible...
  28. T

    Electromagnetics Minus the Fields

    Basically my question is this: could we, in principle, formulate all of classical electromagnetic theory purely in terms of the force one charge exerts on another, or do we need to include the electromagnetic fields in order to arrive at a complete theory? ("complete" as in equivalent to...
  29. genxium

    Derivation of ElectroMagnetics Boundary Conditions

    As learning laser fundumentals, I've just reviewed the boundary conditions for electromagnetic waves. However, I came back to a point that confused me in the past and want to get it clear now :) One of the boundary conditions, regarding the magnetic fields parallel to the medium-interface...
  30. Astronuc

    Advanced Engineering Electromagnetics by Constantine A. Balanis

    Author: Constantine A. Balanis Title: Advanced Engineering Electromagnetics Amazon Link: https://www.amazon.com/dp/0470589485/?tag=pfamazon01-20 Prerequisities: Better part of an Electrical Engineering or Physics BS degree Level: Undergraduate, upper level (4th year); Graduate...
  31. C

    Several questions in electromagnetics

    I went through the book of engineering electromagnetics and I have several questions I don't understand. 1. If the line integral of electrical field is not zero at the existence of changing magnetic field, then how can KVL holds with AC current flowing in the circuit? I do not know what's...
  32. O

    Schools Graduate School Advice: Control Theory vs. Optoelectronics vs. Electromagnetics

    Hey everyone. I'm hoping to get some advice from you guys. I am a senior studying Electrical Engineering. I am currently applying for graduate schools and for graduate fellowships (everything is mostly due mid-December). I plan to pursue a PhD. The only problem is, I'm not entirely sure which...
  33. A

    Electromagnetics coulombs law and field intensity

    Homework Statement The circular region, ρ < a, z= 0, carries a uniform surface charge density ρ ( subscript s). Find E at P(0,0,h), h > 0. Homework Equations Coulombs law Field of a line charge and field of a sheet charge.The Attempt at a Solution I'm not sure what they are asking for , but my...
  34. G

    Electromagnetics Question Circuits

    Homework Statement If V_{s}(t) = 12 sin(4*10^{4}t-\frac{∏}{4}), R = 2 Ω, L = .1 mH and C = .3 mF, obtain an expression for the current though the capacitor. See attached file for circuit. I'm really confused. I applied KVL around the loop with the coil and got that \tilde{I} =...
  35. T

    Increase Electromagnetics emmission?

    First of all - I'm new here, and this forum looks awesome! As for my post, I'm going to be using an inductor to emit an electromagnetic field, and was wondering if you could somehow either increase it or isolate the emission maybe via antenna? I know antennas are typically used to convert...
  36. P

    Conductance per unit length of a co-axial cable (Intro to Electromagnetics)

    Homework Statement Starting with: G = \frac{I}{V}= \frac{-\int_{s}\sigma\mathbf{E}\cdot d\boldsymbol{s}}{-\int_{l}\boldsymbol{E}\cdot d\boldsymbol{l}} Derive the conductance per unit length, G', of a coaxial cable by assuming a line charge of \rho_{l} on the center conductor...
  37. T

    Electromagnetics - parallel plate capacitor energy storage

    Electromagnetics -- parallel plate capacitor energy storage Homework Statement A parallel-plate capacitor 0.5m by 1.0m has a separation distance of 2cm and a voltage difference of 10V. Find the stored energy, assuming that ε=εo. If a 200-volt potential is applied in the capacitor, (a)...
  38. S

    Will not taking Communications or electromagnetics hurt me as an EE?

    At my college we can choose to branch off and focus on computers or more traditional EE classes. I really like E&M physics, but hated my signals and systems course. I'd like to take electromagnetics, but that means I would have to take communcations as well (which I hear has a lot of signals...
  39. P

    Vector review for electromagnetics

    I am a junior EE scheduled to take engineering electromagnetics in the Fall and want to know what math topics are the most useful to review. I know E&M involves quite a bit of vector analysis but I'm not sure how deep into it I should look. For anyone who has taken a similar course, can you...
  40. S

    Which Book is Better for Learning RF Circuit Design: Hayt or Kraus?

    I want buy a book to learn RF circuit design(I have got a project to do next year and I wanted to start preliminary preparation now). Could anyone help me to figure out which one is better of the two - Engineering Electromagnetics by Hayt or Electromagnetics with Applications by Kraus. Thanks
  41. B

    Electromagnetics - Surface Charge Density

    I answered my own question but thank you for the help.
  42. D

    Computational electromagnetics books

    I would like to make an electromagnetic simulator, but I have no experience in this. I have written 3-dimensional ray tracing software for acoustic sources in MATLAB, but I did not include any boundary conditions, it was just propagation in free space through refractions. My only background...
  43. S

    Difference between electromagnetics and electromagnetism ?

    I have come across books titled "engineering electromagnetics" and "electromagnetics with applications" but I could never find a page for electromagentics on Wikipedia. However, there are pages for electrodynamics/electromagnetism/electrostatics on Wikipedia. Is there a difference? If so what...
  44. S

    Engineering electromagnetics field theory

    I am taking a course in Electromagnetic Fields Theory, and the prescribed book for us is Engineering Electromagnetics by William Hayt. We are referring to its 7th edition, in one numerical Example 2.3 we have to find total charge contained in 2 cm length electron beam where as we are given the...
  45. G

    Generator Design Questions (Electromagnetics)

    I am trying to use Faraday’s law to calculate the number of turns a coil requires to produce a certain voltage. This is what I have so far. V = -N * change in (( tesla * area meters squared)/ seconds) becomes N = -1*(-V/ change in (( tesla x area meters squared)/second)) N=-1*(-V/((T*A)/S)...
  46. K

    Electromagnetics: Laplace's Equation Cartesian

    Homework Statement Two long metal plates of length L>>H (their height) intersect each other at right angles. Their cross section is a cross with each line of length H. This configuration is held at a potential V=Vo and the total charge up to a distance d (d<<H) from the center of the cross is...
  47. S

    Electromagnetics - Plane wave reflections/transmissions

    Homework Statement A 1 GHz plane wave is free space is normally incident on a finite-width, lossless dielectric slab (relative permeability, uR of 2, relative permittivity, εR of 18, slab of length l). Determine the narrowest slab length for which 57.14% of power is reflected and the...
  48. 0

    Electromagnetics (Difference in self induction in AC and DC)

    Hello folks. I have an electromagnetics quiz tomorrow and I am kind of nervous. I can't seem to grasp the concept of induction, more importantly how it differs in AC and DC circuits. So in lay terms: Induction is production of electric current across a conductor which is moving through or...
  49. W

    MSEE Electromagnetics, RF and Microwaves + ?

    The program I am looking at has an emphasis on Electromagnetics, RF and Microwaves. If I am looking at the telecommunications industry, what other exposure might be valuable? Would some course work in Signal processing or embedded systems be beneficial?
  50. F

    Basic questions about electromagnetics , quickly

    Hi All , if we have 2 charges +ve and -ve ... how Electric and Magnetic fields are been created between them and also how they will move to create magnetic field and how they will travel (propagate) ? thanks for help !
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