1. ### I Equivalence principle: an electric charge and a coil

The near-range magnetic field ##\vec{B}## of a point charge ##q## at distance ##\vec{r}##, moving at a non-relativistic velocity ##\vec{v}##, is given by $$\vec{B}=\frac{q}{4\pi\epsilon_0c^2}\frac{\vec{v}\times\hat{r}}{r^2}.$$ Faraday's law of induction for the induced EMF ##V_c## in a coil...

3. ### Suggest a geometry for headphone's speaker system

Summary:: Suggest a geometry Hello! I have difficulties with this question. It is translated from Swedish so if something's weird tell me. The speakers in headphones often work with the help of magnetism, when a varying voltage is applied across a coil attached to the speaker membrane. The...
4. ### A Can the displacement current be equal to and opposite in sign to the conduction current so the total current will be zero?

If so, what will I measure in the Ampermeter, the zero total current or the value of the conduction current? I was thinking of the following example- a circuit consist of a current source, an Ampermeter, a switch, and a semiconductor. The semiconductor can have both conduction and displacement...
5. ### I Average of the B-field over a volume and surface integrals

Purcell says that taking the surface integral of the magnetic field ##\textbf{B}## over the surfaces ##S_{1}, S_{2}, S_{3},...## below is a good way of finding the average of the volume integral of ##\textbf{B}## in the neighborhood of these surfaces. More specifically, he says in page...
6. ### E&M Exam Question, I want to know what I did wrong

(the second attached file)
7. ### Torque on a circular current loop

Can anyone please tell me why the torque on a circular current loop can be calculated by the equation below? In other words, what is the intuition for the formula? Thank you. (I modified my question to a particular case) $$\vec{\tau} = I \vec{A} \times \vec{B}$$
8. ### B Refraction of light -- What is the best description for 10th grade physics students?

In my latest 10th grade physics lesson, we were learning about the refraction of light. I decided to share what I knew about why light slows down in a vacuum, which is, in short, because the electric field of the electromagnetic wave exerts a force on the charged electrons of a medium, which in...
9. ### Radiation detector - cylindrical ionising chamber

Let r = position of the electron = 6mm - 36.8μm; λ = mean free path traversed. Integrate E(r) = Q/(2πϵLr) between the two shells gives: V = [Q/(2πϵL)]*log(r/(r-λ)) I know that the question is asking for the voltage at which the electron energy will get to 23eV, but i am unsure how to get rid...
10. ### Electric field direction on a grounded conducting sphere

I am required to find the direction of the electric field on the surface of a grounded conducting sphere in the proximity of a point charge ##+q##. The distance between the center of the sphere and the point charge is ##d## and using the method of images we find that the charge of the sphere is...
11. ### Classical Rigorous introductory books on Electromagnetism

I need some rigorous introductory books on Electromagnetism, by rigorous I mean detailed and mathematical. Many books that I have found don’t actually work out the field produced by current carrying toroid, solenoid or even some other simple electrostatic situations. They just write “by...
12. ### Textbooks to be used as references for classical electromagnetism

Summary:: I need to add references for several classical electromagnetism concepts, I would like to know which books deal with these concepts. Recently a paper about classical electromagnetism that I had submitted was rejected, among other reasons because it contained many references to...
13. ### I Rearranging the equation for the cutoff condition in optical fibers

Hello! In Optical fibers, let ##k_1## and ##k_2## be respectively the propagation constants in core and cladding, ##\beta## the propagation costant of a mode along the direction ##z##, ##a## the radius of the fiber. Using the normalized quantities ##u=a \sqrt{k_1^2 − \beta^2}## and ##w=a...

24. ### I Derivation of ideal magnetic dipole field strength

For reference, this is from Griffiths, introduction to quantum mechanics electrodynamics, p253-255 When deriving the ideal magnetic dipole field strength, if we put the moment m at origin and make it parallel to the z-axis, the book went from the vector potential A  A=...
25. ### A Aharonov - Bohm effect exercise

Does anyone know the answers to this, or can hopefully guide me to a text that will help me solve this aharonov-bohm problem? Here is the given: Particles (of mass m, and charge q), are driven through two slits that have distance d between them, in a screen that is far away (L>>d) from the...

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27. ### How to transmit a signal (530 - 550 Khz) to a point

Hi everyone, I'm pretty new to electromagnetism and have no experiences in this topic. I have a signal generator (Digital Dual Channel Funktion Signal Generator) and want to generate two signals (530 and 550 Khz signal) and want to transmit these generated signals to the points on a table...
28. ### What will the phasor diagram of this LCR circuit looks like?

I know the current of capacitor and inductor must be parallel but pointing in opposite direction due to the fact they are connected in parallel thus having same voltage (please see attached screenshots). The current of resistor will simply be the sum of these two vectors, but what about its...
29. ### I Consistent Treatment of Forces

Under Newton, gravity is what I term an "invisible magic rope" that pulls you down. Enter Einstein. We do away with the invisible magic rope, and say that space (or space-time) is warped by mass. However, we still have other forces, that (as far as I know, anyway) are "invisible magic ropes."...
30. ### I Why am I getting Maxwell's second equation wrong?

While going through an article titled "Reflections in Maxwell's treatise" a misunderstanding popped out at page 227 and 228. Consider the following equations ##(23\ a)## and ##(23\ c)## in the article (avoiding the surface integral): ##\displaystyle \psi_m (\mathbf{r})=-\dfrac{1}{4 \pi} \int_V...