Magnetic field Definition and 1000 Threads

Boundary conditions: The derived Dirichlet and Neumann boundary conditions In terms of the magnetic scalar potential:

TL;DR Summary: There is a loop of wire placed in a changing magnetic field, there will be an induced electric field here. I am wondering if there can be a potential difference here? Here is the problem: A conducting square loop symmetrically encloses a solenoid of radius ##R##. The magnetic...

Hello everyone, This is my first post on this platform, I'm excited to be a part of this community! I'm currently doing a research project on Nuclear Fusion, and have been recently introduced to the concept of Magnetized Linear Inertial Fusion (MagLIF). I'm still new to the topic of...

With distance from the source the feild strength is reduced. Do the electrons travel slower the further from the source ? And thus faster closer to the source. Or is the feild strength reduced simply because there are less electrons but the speed of them is the same as inner feild. I'm asking...

As the homework statement suggests

How is there a uniform electric field between two parallel metal plates? Okay, I can understand it through electric field lines. But how can this be quantitatively confirmed? My intuition is that as the charge approaches the metal plate, r becomes very small, so according to Coulomb's law, a...

A week ago, I started studying electromagnetism. I was introduced to a few new concepts and one of them was H. Now, in my book, they defined H as just magnetic field strength and B as magnetic induction. The thing is, I don't understand what those terms really are (in a physical way), let alone...

Hi there, I am working on a research paper and I need to determine the force with which the magnetic field of a coil acts on an small (pink-pong sized) iron ball. I tried to search for the force, acting of three dimensional object in magnetic field, but the only force I found was: F = q0vB I...

Given a test charge moving along a current carrying wire, I'm familiar with the relativity explanation of the magnetic field at the rest frame of the wire and the electric field In the moving particle frame (where the wire is electrically charged). My question is how relativity kicks in in the...

Let's say we have an LC circuit and we begin with the capacitor fully charged, it then starts discharging, and currents begins to flow in the circuit, and a magnetic field is generated in the inductor because of the current flowing through it. My question is, why is the magnetic field in this...

The original question was to find the final velocity after falling from the height ##H## In many correct solutions to this problem, they consider the current density between the two surfaces to be ##\displaystyle J=\frac{1}{\rho } .\mathbf{E^{*}} =\frac{\mathbf{v} \times \mathbf{B}}{\rho }##...

Influencing electrons angular momentum You can use magnetic fields to influence the intrinsic value of angular momentum (spin). When an electron interacts with a magnetic field it experiences a force known as torque – twisting force in the direction of the magnetic field. Therefore, if you pass...

Here is a picture depicting the capacitor and the points of interest. I approached this problem by applying the Ampere-Maxwell law. For each point I used an circular Amperian loop that I denote by ##P##, enclosing a circular surface ##S##. Thus, for point ##b## we have...

According to the special theory of relativity the electric and magnetic fields observed from a charge distribution should depend on the relative motion of the observer. For example consider a linear arrangement of point charges which are fixed relative to each other. An observer who is...

My answer is (B) but the answer key is (A). My working: $$\varepsilon=-\frac{d\phi}{dt}$$ $$=-AB\frac{cos\omega t}{dt}$$ $$=AB\omega \sin \omega t$$ Why the answer is zero? I thought the flux will be zero, not the emf. Thanks

I understand that the Quantum Hall Effect explains how both the transverse and longitudinal resistance vary with magnetic field strength. I don’t get why the hall resistance is equal to the hall voltage over the current . I know current isn’t a vector quantity but isn’t the hall resistance an...

My issue is with the signs. We have $$\mathcal{E}=\oint \vec{v}\times\vec{B}\cdot d\vec{s}$$ $$=\oint v_0\hat{i}\times B_0(-\hat{k})\cdot dy\hat{j}$$ $$=\int_0^h v_0B_0\hat{j}\cdot dy \hat{j}$$ $$=v_0Bh$$ Now, apparently, the sign should be negative. Intuitively, the magnetic force on any...

Hi, I am struggling to get the right answer for this question. My first thought was that I should consider to what direction does each segment of wire have a force towards. I found the direction to be in the following (see red arrows): My past attempt was: Floop = [FONT=book...

I will present the case as an exercise because I believe it will be easier to understand that way. I didn't know if I should post it under the mechanics or electromagnetism sections because I am actually trying to link both. Since it feels like a fairly simple problem, I considered the Classical...

In my opinion, the magnetic field at point P should cancel each other, because the magnetic field caused by the two wires has the same direction, like this. but the solution does not assume that the magnetic fields cancel each other out. I don't know where I'm wrong, please help me, thanks.

For the following conductor loop, determine the magnetic field along the ##z##-axis, which passes through the center of the conductor loop and is perpendicular to it. The conductor loop consists of an infinitely long wire through which a constant current ##I## runs. Is it possible to determine...

I remember one of my favorite parts of the original Star Wars movie was when Luke, Leia, Chewie and Han jump into the trash compactor. Han tries to blast his way out and the blaster bolt ricochets off the walls of the compactor until it eventually hits a piece of garbage. Luke screams “WILL YOU...

Sorry for this question: how does a compass (or its electrons) know that it is in a magnetic field? Is it the information of the photons that cross it? (photons are what transmit electromagnetic forces)

I learned that diamagnetism is due to Lenz's law. But doesn't Lenz's law only apply when the magnetic field changes? Why does diamagnetism occur even when a constant magnetic field is applied without change?

From Ampere's law, ##\displaystyle\oint\vec B\cdot d\vec l=\mu_0 I## where ##r## is the distance from the wire ##B\cdot 2\pi r=\mu_0 I## ##\displaystyle 91.4\times 2\pi\left(\frac{2}{100}\right)=4\pi\times 10^{-7} I## ##I=91.4\times 10^5\ A=9.14\ \rm{MA}## But the answer given in the...

How much power (Megawatts) would it require if we were to create a magnetic field as large and strong as the Earth's magnetic field?. I haven't learned how to calculate this, but just curious.

I want to derive the electric and magnetic field at a point around an infinitely long wire which carries a sinusoidal alternating current. And I want the answer includes the phase delay according to the limited speed of propagation of the wave. Surely the answer must satisfy the Maxwell's...

Hi, I was wondering if a Magnetic Resonance (+contrast) can in some way modify the structure of artificial chordae used in heart surgery. My first answer would be "No". There ain't any medical article about that. Also (as far as i know) I don't think magnetic field can break chemical bond, so it...

##\displaystyle R=\frac{mv}{qB}\implies v=\frac{RqB}{m}## where ##v## is the speed of the proton ##\displaystyle\frac{dv}{dt}=\frac{Rq}{m}\frac{dB}{dt}## On substituting the values, I get ##\displaystyle\frac{dv}{dt}=9.58\times 10^4\ m/s^2## This answer, however, is incorrect. Where have I...

Consider a circular Amperian loop oriented counterclockwise that is concentric with the circles in the figure and passes through P. By symmetry, ##\vec{B}## is everywhere tangent to this circular loop and has the same magnitude B everywhere on the circle. By Ampere's law...

What would be the consequence if a powerful (1 Tesla) magnetic field came into proximity of Earth? Options open concerning size of generating body and distance. Thank You.

I've dissected a pig (flashlight) and found a hand crank generator that has a multipole ring magnet. I used a bar magnet to establish that it was a multipole magnet, because I was wondering if I could figure out the direction of the current based on the direction of the magnetic field. My...

Why isn't EM radiation attracted/repelled by a magnetic field?

I have few cylindrical neodymium magnets of same diameter and different heights and different magnetic inductions in the geometric center of the magnetic pole surface. Knowing those values of magnetic induction, how can I measure what the induction is at a certain distance from that center? For...

For this question part d, KE=mv^2/2=q^2B^2r^2/2m (I rearranged B=mv/qr for v and subbed into mv^2/2). q^2b^2r^2/2m=2F_cyc^2r^2m(pi)^2 But when I subbed the values in I got 16.45MeV but the answer says 165keV instead. I'm not sure what went wrong? What's a good explanation for part e also?

Hello. Sorry. I am not a physicist and I have very superficial knowledge of the subject. I would like to ask a question about the practical field. I only have a device that measures the electric field. When I measure the signal coming from a cell phone tower before it is reflected from a metal...

Hi. Very simplified schematics of railguns all look like this: I have trouble properly understanding this. So apparently there is still a significant magnetic field where the projectile is, even though that's where the current stops flowing through the rails? Of course the magnetic field...

Imagine a very large disc with current converging to it's center as $$ I=- \frac{k}{r} \hat{r}$$ Obviously ##\theta## is absent in the equation so the magnetic field by this current should look the same no matter which angle one is observing. Then does this mean that the magnetic field is...

The current in a wire is said to produce a magnetic field and a force on a charge. It is said that the correct way to interpret the effect is because of relativity. So does that mean that that the most basic non-relativistic equations that offer basic calculations of the forces and fields are...

Here is my attempt to answer the questions: a. The system's motion is a combination of two types of motion: the translational motion of the center of mass and the rotational motion of the charges around the center of mass. The forces acting on the system are the Lorentz force, which is the...

I was thinking of using magnetic monopoles, but I don't know how to do. I tried to calculate the magnetic flux through the cross section of the solenoid if a current ##I## flows through it. Magnetic induction inside can be given as ##B = \mu_0 n I##, whereas magnetic induction at a distance...

Hello, I am stuck on a problem that I don't quite understand, which looks like this: "Given a nonmagnetic material with the magnetic field H = 50⋅exp(−100⋅x)⋅cos(2π⋅10⁹⋅t − 200⋅x)⋅ŷ determine the electric field strength E" I don't understand how I am supposed to find the solution for this...

A current carrying conductor experiences magnetic force in a magnetic field. F=BILsinθ Where, B = Magnetic flux density I = Current L = Length of conductor and θ = Angle between magnetic field and current This force is due to free electrons moving in a...

Hi, unfortunately, I am not sure if I have calculated the task correctly here Task a I have now proceeded in such a way that I thought that the magnetic field only flows through the area drawn in red. Which ##\frac{1}{4}## corresponds to the area of a circle. By the fact that the magnetic...

I have a simulated data of charged particles in a magnetic field. I have selected clusters, each cluster contains a set of points(x,z) and I want to perform RK4 between the first and second clusters and fill the positions in a histogram. I have selected the clusters with the initial...

from the partition function - am trying to show that ##\langle \mu \rangle = \beta^{-1} (\partial \log Z / \partial B)## where ##Z## is the canonical partition function for one atom, i.e. ##Z = \sum_{m=-j}^{j} \mathrm{exp}(\mu_0 \beta B m)##, and ##\mu = \mu_0 m##. The average...

Hi, I am confused about whether decreasing the magnetic field used for a generator could increase the generator's power output. I used four equations: 1. Torque = Force x radius 2. Torque = NIAB (N = number of turns, I = current, A = area of armature, B = magnetic field). 3. emf =...

How does an electric field of a moving charge, for example a moving electron, inside a wire looks like? Does it looks like this with distorted circular radial lines?

Problem: Solution part a) where formula 6.14 is just M x n. We need to do part b without seperation of variables, I'm quite stuck. Will B just be the magnetic field inside a solenoid? How can I find the other fields.