Magnetic Definition and 1000 Threads

Seven years ago, I wanted to share and discuss my experiments results there but it was not possible since there was no published peer review paper yet and apparently not fulfilling forum requirements. Now we have such a publication, but still not sure the subject can be discussed here. Anyway...

d(ɣmv)/dt = qvB (dɣ/dt)mv + ɣm(dv/dt) = qvB Substituting gamma in and using the chain rule, it ends up simplifying to the following: ɣ^3*m(dv/dt) = qvB Now, I am confused on how to solve for v.

I am trying to derive radial and axial magnetic fields of a current carrying loop from its magnetic vector potential. So far, I have succeeded in deriving the radial field but axial field derivation gives me trouble. My derivation of radial field (eq 1) can be found here. Can anyone point out...

I seem to hear about huge astronomical events that generate radio waves seem to come from objects with huge magnetic fields, such as neutron stars and black holes. Does that mean magnetic fields only come from the radio end of the spectrum, and not higher frequencies, like IR, UV, X-rays, etc?

To solve this problem, we need to evaluate the following integral: $$\epsilon = \int_{P}^{C} (\vec v \times \vec B) \vec dl$$ The main problem is, in fact, how do we arrive at it! I can't see why a Electric field arises at the configuration here. The magnetic field of the rotating sphere is...

We know that we need to go to 5th order in perturbation theory to match 10 decimals of g-2 for electron, theory vs. experiment. But let us not assume QED is pure and independent, but it's a lower energy limit of GSW (not Green-Schwartz-Witten from superstrings) electroweak theory. Has anyone...

If a magnetar is a neutron star, how do the neutrons composing the star generate a magnetic field? A neutron has zero charge, so it generates no magnetic field.

My solution was as follows: $$\frac {d\overrightarrow p} {dt}=q \frac {\overrightarrow v} {c}\times \overrightarrow B_0$$ The movement is in the ##[yz]## plane so ##|\overrightarrow v\times \overrightarrow B_0|=vB_0##, therefore: $$\biggr |\frac {dp} {dt}\biggr |= \frac {qvB_0} {c}.$$ On the...

Hi, here's a theoretical problem that I am trying to find a satisfactory answer for. Imagine a coil that is temporarily switched on an off and generates a magnetic field that permeates through space. Now imagine a charged particle passing through this field, at time that the coil is already...

The magnetic flux ##\phi_m = \int{BdA}## The magnetic field of the coaxial cable B = ##\frac{I_{enc} \mu_0}{2\pi r}## since surface area of a cylinder = ##2\pi rdr L, dA = 2\pi L dr## where L is the length of the coaxial cable so ##\phi_m = \int{\frac{I_{enc} \mu_0}{2\pi r}2\pi L dr}##?

Hi, I am willing to simulate a 3D ferrite bar transmitter and reciever where coupling coefficient k and Bt magnetic flux density on the each side uses the finite element method for solving partial differential equations. The Magnetic Fields module has equation (jωσ − ω2ε0εr)A + ∇ × H = Je...

If we increase the magnetic field, the radius of the particle's circular path will decrease which increases the tangential acceleration. How do I find the tangential acceleration. Do I use derivatives?

If I'm correct then the maximum change in magnetic flux occurs when the semi circle crosses the point at which it's plane is parallel with the magnetic field and minimal when it crosses the point at which the magnetic flux is maximum ( perpendicular with the field). I'm having trouble writing a...

##B_0 = \frac{\mu_0(N)(I)}{2\pi r}## ##\frac{N}{2\pi r} = 200## ##B_{net} = B_0 + B_m = (1+X)\times B_0## Plugging in the numbers: ##B_0 = 4\pi\times 10^{-7}(200)(1.5) = 3.8\times 10^{-4}## ##B_{net} = (1+X)\times B_0 = (1+ 3\times 10^3)\times 3.8\times 10^{-4}## = 1.13 T But the answers says...

At first I tried plugging everything in with 60Hz in the numerator but that did not work. I was told to think about sinusoidal waves and derivates but I'm not sure how that works. Any ideas? Thanks a lot

Does electron beam in empty space generate magnetic fields around them just as with current in conductor. If yes, then is it experimentally proven that two parallel electron beam would attract each other.

Can someone explain how there can be a radial magnetic field? I thought the magnetic field was always tangent to the circle using the right hand rule where you wrap your fingers around the current and point your thumb in the direction of the current.

if a sphere rotates, it's like multiple currents going around in a circle. I can find the magnetic field of each of those currents at the center point of the circle and add them together. We can integrate with respect to y and R. y ranges from 0 to 5 cm away from the center of the loop and the...

I am confused about this, do the black arrows represent the direction of magnetic force? The torque ##\tau = -IABsin\theta##, where I = current A is area of loop and B is magnetic field strength and I am a little confused how ##\theta## here is 45 degrees when the angle between the normal for...

I am a beginning graduate student and I've been assigned a paper which uses landau levels for 3d fermionic gas in uniform background magnetic field. I am having trouble finding a proper source which deals with solution of dirac equation in such a case. With the two papers that i have found which...

I was wondering if anyone could walk me though a better explanation on how to get the given results for these two questions. The solutions posted by my professor aren't really clear to me so if anyone is able to better explain how to get the solution it would be much appreciated!

Hello! Assume I create an atom by some non-state-selective method (e.g. laser ablation, or hitting a proton on a target) and let's say that the atom is in a ##J=1## state. In the absence of magnetic fields, the ##m_J = 0, \pm 1## levels are degenerate. If I am to define arbitrary a z-axis (say...

If the question had been asking about the flux through the whole surface of the cylinder I would have said that the flux is 0, but since it is asking only about the lateral surfaces I am wondering how one could calculate such a flux not knowing how the cylinder is oriented in space. One could...

I am building small, simple version of a railgun using 2 copper bars and a couple of neodymium magnets to increase the magnetic field. I have also been trying to mathematically describe the magnetic field created by the conducting rods themselves. I am coming across some trouble when trying to...

Hello there, I am given a diagram of a Josephson Junction like so: With a magnetic field ##B = \mu_oH## in the z-direction. I'm reasonably sure ##d_x,d_y,d_z## are normal lengths, not infinitesimal lengths although that is up for debate. Using the above equations I rearrange the expression...

I want to improve the magnetic field strength at the surface of a magnet configuration by utilizing diamagnetic materials to guide the magnetic field lines. I have not the proper equipment to measure the effect myself but would this work? This is the initial configuration with four magnets side...

Suppose a molecule from our surrounding air (at ambient temperature) is being selected and is ionized. By some mechanical means, some velocity (say 100 m/s) is added to it and it has been put into a magnetic field perpendicular to its direction of motion. We all know how the molecule will behave...

I was wondering, if the magnet train is propelled by putting same polar magnet face each other at an angle and its natural magnetic property same pole repel, that's how it'spushing the train faster and faster...now what if we create a circular tunnel and have the train push itself and repel...

Einstein famously said “{Thermodynamics} is the only physical theory of universal content, which I am convinced, that within the framework of applicability of its basic concepts will never be overthrown.” I don't think any of us want to argue with Einstein, but it's worth noting the "within the...

Science project. Real generator. But self made generator multiple magnets. What happens if I spin bar magnets inside a copper wire ring? Instead of rotating 2 separate copper rings inside a magnet that will split different flowing current on to different wires where a brush can join them...

If the question had mentioned ##\overrightarrow{E}## instead of ##E_\bot##, then we could have used ##\overrightarrow{B}=\dfrac{1}{v}\widehat{k}\times \overrightarrow{E}## to get the direction of the magnetic field. But the question had only mentioned ##E_\bot##. To my understanding, knowing...

Hello there, for the above problem the wavefunctions can be shown to be: $$\psi_{n,l}=\left[ \frac {b}{2\pi l_b^2} \frac{n!}{2^l(n+l)!}\right]^{\frac12} \exp{(-il\theta - \frac {r^2\sqrt{b}}{4l_b^2})} \left( \frac {r\sqrt{b}}{l_b}\right)^lL_n^l(\frac {r^2b}{4l_b^2})$$ Here ##b = \sqrt{1 +...

I'm trying to figure out what kind of magnetic sensor is used in my wristwatch (Casio Edifice twin sensor) a d how it works. Just out of curiosity. After some research, I got some clues. So, the first thing I'd like to know is how a magnetoimpedance sensor works? How is its circuitry? Some...

Plug in the elementary charge for q, 1000 m/s for v, 50 microtesla for B and 90 degrees for theta and I get about 8e-21 Netwons. But apparently this is wrong, anyone know why? Thank you.

What benefit does a v-shape magnetic accelerator (image 1) have over a linear magnetic accelerator (image 2)? Image 1: v-shape Image 2: linear The v-shape magnetic accelerator appears to increase the ball's average speed with a larger angle. What is the physics behind this?

I have to prove three equations above. For first two equations, I've been thought and made reasonable answer by using a definition of the electricfield. However, for third, I can't use a definition of a magnetic field due to the cross product Like J_2 X J_1 X (r_2 - r_1). I think three of 'em...

We know cobalt is a magnetic material, it can attracted by magnet. Now if we want to know for example cobalt oxide (co3o4) has magnetic property or not what we should do? I mean is there a role to know bonding of cobalt with which elements results in magnetic property? or is there any online...

To calculate the Hamiltonian of a charged particle immersed in an electromagnetic field, one calculates the Lagrangian with Euler's equation obtaining ##L=\frac{1}{2}mv^2-e\phi+e\vec{v}\cdot\vec{A}## where ##\phi## is the scalar potential and ##\vec{A}## the vector potential, and then we go to...

So I'm familiar with the magnet falling through a copper tube demonstration that shows the induced magnetic fields slowing the magnet down. I know that this experiment is also possible with a conducting coil as long as the coil forms a closed circuit. I'm trying to find a way to calculate the...

I don't understand why there is potential difference between point A and O. Is there any change in magnetic flux experienced by the ring? I think the magnetic field passing through the ring's cross sectional area is constant Thanks

I have found articles that show T1 and T2 values for mineral oil and I compare them to mine and there is over 50% error also I know that T1>T2 but mine numbers don't follow that scheme.

Hi, I'm wondering if I have an expression for the scalar magnetic potential (V_in) and (V_out) inside and outside a magnetic cylinder and the potential is continue everywhere, which mean ##V^1 - V^2 = 0## at the boundary. Does it means that ##V^1 - V^2 = V_{in} - V_{out} = 0## ?

I actually have no idea how to begin. Thanks for help 😊

Hi all, as we all know EM waves are made up of magnetic and electric waves in a plane perpendicular to the direction of propagation. Given this, why don't I see conductors being affected when I shine light at them? Woulnt the magnetism cause a force? Is is that the force is too small? What am i...

[Mentor Note -- Two similar thread starts merged into one] Hey all, I have been working on this project for a while now, which features suspending an object midair through the use of magnetic levitation principles. Cool right? And so I have been researching and trying, even finding ground...

I want to wrap no. 16 copper wire around 1" copper pipe to create a mag field. At 120v / 1 amp AC, how many turns will I need to get about 5 milligauss near the pipe?

Hi. A electromagnetic wave consists of an electric and a magnetic component. I believe that the electric field strength is measured in volts per meter. The magnetic field I think is measured in Tesla. Let's imagine that I measure the electic field strength of two different radio stations and...

Hi, We know that a varying magnetic field creates and induced electric field, and a varying electric field creates an induced magnetic field. If there is a varying electric field (let's say sinusoidal), then this electric field creates an induced magnetic field. And if this produced magnetic...

I've just started Quantum mechanics by McIntyre and have understood the following about operators which the author wrote till chapter 2: Each observable has an operator Operators act on kets to produce another kets. Only eigenvalues of an operator are possible values of a measurement. Now...

Consider an uncharged particle with spin one-half moving with speed ##v## in a region with magnetic field ##\textbf{B}=B\textbf{e}_z##. In a certain length ##L## of the particle's path, there is an additional, weak magnetic field ##\textbf{B}_\perp=B_\perp \textbf{e}_x##. Assuming the electron...