Magnetic field Definition and 1000 Threads

Hello, Short description: In my country's physics olympics, if a loop of wire is moved in a changing magnetic field, the time derivative of the area (while calculating emf with lenz law) is the velocity of the loop (as if we're taking the time derivative of the AREA SWEPT). This has became an...

how can a rectangular coil placed in uniform magnetic field have torque? Isn't torque the force on an object while its rotating? Will the coil rotate in a magnetic field? I don't understand.

Homework Statement The actual question was to somehow derive the expression for a magnetic field at the center of a current carrying loop. Homework Equations The Biot-Savart's law equation dB = (mu/4π)*(i dl x r)/r^3 (I'm not actually good at typing in the equations, so please just forgive...

Let's say I have a disk magnet that is a centimeter thick and 1 meter in diameter. Now let's apply an external field confined to a cylinder of arbitrary position, angle, and length. Let's say it has a diameter of << 1 meter, so very, very narrow. Let's presume that the external field lines are...

Electrons have spin 1/2 and interact with a magnetic field. Since photons have spin 1, I suppose they also feels a force on a magnetic field. So that means that light can be deviated from its original path by a magnetic field?

A varying magnetic flux causes an induced voltage (according to Faraday-Lenz law) that generates a current that generates a magnetic field that generates another magnetic flux in the same circuit. Does the Faraday-Lenz law include this self induction? Or are they giving us a simplification in...

Homework Statement Problem given in the image attached. Uniform Magnetic Field : B Positive Charge : q Uniform Velocity : v Mass : m Charged particle enters the magnetic field making an angle θ with the plane perpendicular to the magnetic field. Width of the region of Magnetic field : d d <...

Magnetic field is created when electrons move in the conductor, as far as I know. In the electric circuit electrons move with a speed of few mm/s when the circuit is closed. So, if I took a piece of wire and moved it, would it generate magnetic field? I suspect not, but I am wondering what is...

Homework Statement Two particles with spin S_1={1 \over 2} and S_2={1 \over 2} are at t=0 in a state with S=0. a) Find wave function at t=0 in S_{1z},, S_{2z} basis. b) Second particle is in a magnetic field B = (\sin\theta,0,\cos\theta), the Hamiltonian is H=\lambda \vec{S_2} \cdot \vec{B}...

If the amplitude of gravitational waves, frequency of gravitational waves and the vector potential of magnetic field in surrounding of such waves are known then what would be the easiest way to calculate resultant acceleration of electrons? My above question is based on the various researches...

Homework Statement There's a uniform infinite line charge with the charge density λ. A point particle with charge q moves with a velocity v parellel to infinite line. What is force exerted on point particle? What is magnetic field seen in ths moving frame(particle frame)? Homework Equations...

Let ##\boldsymbol{l}:\mathbb{R}\to\mathbb{R}^3## be the piecewise smooth parametrization of an infinitely long curve ##\gamma\subset\mathbb{R}^3##. Let us define $$\boldsymbol{B}(\boldsymbol{x})=\frac{\mu_0...

This is the question: At a certain location in the Philippines, Earth’s magnetic field of 39 µT is horizontal and directed due north. Suppose the net field is zero exactly 8.0 cm above a long, straight, horizontal wire that carries a constant current. What are the magnitude and direction of the...

Hello, First of all, this question does stem from graduate work, but it seems far too simple to tag "advanced". I am looking to write some code to simulate the force from a railgun. The first step in doing this (from a tutorial I found) is to find the magnetic field at any point within the...

So I am constructing an analogy between the self replicating fracturing effect on thin films and the path of a charged particle. (Qualitatively, several cracks have similar shapes to charged particle motion) I won't go into the details of the fracture mechanics, so I will only use E+M...

A charge moving relative to some observer produces magnetic field in space around it. Now I want to ask that how does the magnetic field of the charge at any fixed point varies as the charge passes by. Or is the B field only dependent on current and not a single moving charge? If I introduce...

When there is a magnetic dipole placed in an external non uniform magnetic field, will it experience a net force?

Hi. I was browsing Wikipedia on a topic, went to magnetic bearings, etc etc...ended up on synchrotron radiation then the phrase about how a moving or accelerat/ing/ed particle passing through a magnetic field generates electromagnetic radiation. Then I has a revelation. How to get a particle...

Hi, hopefully someone here can help me! I'm interested in Halbach Arrays and specifically I want to make a circular array in which the field is amplified away from the array (as in above or below it), not to its inner diameter (or exterior circumference). Is this possible? On the web I've seen...

Of what consist magnetic field? Someone says that magnetic field consist of photon, is it true? Thanks in advance for your answers

I know that magnetic fields can align objects with spin. In that case, if we suspend an object and turn on a magnetic field such that a significant number of electrons become aligned with the field, could we observe a macroscopic change in angular momentum?

I was curious to the effects of a strong electromagnetic field applied to an object at distance. The field must be able to quickly activate and deactivate in order to account for the distance traveled towards the object as to eliminate the force applied to the source of the field by the object...

Homework Statement The orbit of an electron (-e) around a nucleus (Ze) is a circular orbit of radius a in a plane perpendicular to a uniform magnetic field \textbf{B}. By writing the equation of motion in a frame rotating with the electron, show that the angular velocity \omega is given by one...

Homework Statement A spin-1/2 electron in a magnetic field can be regarded as a qubit with Hamiltonian $$\hat{H} = \frac{1}{2}g\mu_B\textbf{B}\cdot\boldsymbol\sigma$$. This matrix can be written in the form of a qubit matrix $$ \begin{pmatrix} \frac{1}{2}\epsilon & t\\ t^* &...

Homework Statement Hi everyone. I was reading through a book and came across the following question and explanation: " You are given two 200 meter strands of identical copper wire. With one strand you create a coil whose radius is 2 cm. With the second strand you create a 4 cm coil. Assuming...

Hello everyone! I want to know how to compute the force applied on ferrous inside a non-uniform magnetic field, to make it easier, let's assume that the field direction is constant, and the magnitude decreases linearly. Now, I know that ferromagnetic material inside a magnetic field will...

Hello everyone, How can I calculate the partition function of N classical electrons (forgetting about the spin) in a box of volume V with Hamiltonian (The Hamiltonian is missing a factor of 1/(2m)) ? I tried calculating the partition function of one electron first in the canonical ensemble but...

I suppose that my main question is how to find the induced electric field given a time-dependent magnetic field, but i will demonstrate my question with an example: I constructed a simple magnetic field B = b*tz , permeating the whole space. The induced electric field will lie in the xy...

Homework Statement Two coencenteric metalic shell has inner radius $r_1$ outer radius $r_2$. We place along axis infinity wire has $\lambda$ charge in per unit length. The inner region of metalic shells inserted with relative permabilitty coefficent $\epsilon$. This system rotates with $\omega$...

I need help in calculating the magnetic field outside of an iron core solenoid at different distances. I have made an electromagnet by taking a 99.99% pure iron (5cm in length and 1 mm in radius) and wrapping wire over it. I have measured it's magnetic field at the end and cannot find an...

Hey I got a little imaginary experiment which is little bit confusing to me. Maybe somebody with knowledge in signal transmitting or just good knowledge of physics can help me out. So let's say there are two parallel conductors which length is endless and resistance is zero (no losses and...

I was wondering at what point the strength of the magnetic of a magnet was mea. I assume it would not be the origin of the field which would be inside the magnet and not the side of the magnet itself as the value would be dependant of the size of the magnet. Is there a standard of where to...

Hey guys, i just came across this on my classical physics course. So, I'm given that: E(z, t) = {E_{0}}sin(wt)sin(kz)\widehat{x}, and I'm supposed to find an expression for the associated magnetic field B. Usually, i just find the propagation direction, and do it's cross product with the...

I am interested in mini magnetospheres. How do i calculate the intensity of the field at a certain distance if i already know theits intensity at the source?

Since the field in the title is opposing the original magnetic flux that causes the induction, how can it be reduced? I understand that a laminated magnetic core can be used. 1) Where is this magnetic laminated core placed? 2) Can it be obtained from specialized manufacturers? 3) My choice for...

since magnetic field lines form closed loops , field inside Earth must be due geographic south will compass below Earth's surface point to geographic south?

This seems simple but i cannot find an answer anywhere. First off: is iron attracted to a magnet because the field strength on the side of the iron object closest to the magnet is stronger than the one furthest? And if this is true, how can one use this "differential" magnetic field to calculate...

Let ##V\subset\mathbb{R}^3## be an infinitely high solid cylinder, or a cylindrical shell of radii ##R_1<R_2##, whose axis has the direction of the unit vector ##\mathbf{k}##. For any point of coordinates ##\boldsymbol{r}\notin \bar{V}## external to ##V## the Lebesgue integral (which is...

<< Mentor Note -- Thread moved from the technical forums,. so no HH Template is shown >> Hello! I have a question on Electromagnetics. Could anyone check if I am on the right track? Here is the proposed problem: Consider a spherically symmetric current distribution, which is radial and...

Hi! I'm getting ready for an exam and want to make sure if I solved some problems correctly. I would be grateful for your feedback :smile: 1. Homework Statement After going through potential difference of 5000 V an electron falls in uniform magnetic field. It’s induction is 0.1T and the...

Homework Statement True or not true:[/B] Equipotential surfaces of the magnetic field are no closed surfaces but extend to infinity Homework Equations - The Attempt at a Solution I think it is true, because they are perpendicular to the (closed) magnetic field lines, but I am not sure...

Homework Statement A circular single loop of wire with a diameter of 20.0 cm lies in the plane of the paper in a region of space that contains a 1.75 T magnetic field pointing out of the paper. a) Determine the magnetic flux through this loop. b) If the diameter of the loop changes from 20.0...

The force on a magnetic dipole in a magnetic field is the dot product of the magnetic moment and the gradient of the field B, but gradients are operations done on scalar fields to produce vector fields. How does one calculate the gradient of a vector field if field gradients are only defined...

I was researching the relationship between magnetic dipoles and chemical bonding and I came across a very interesting paper. I'm hoping some of you can shed some light on how magnetic fields are making dissociation of a molecule possible and how to measure it...

Homework Statement Suppose the magnetic field line pattern is cylindrical symmetric. Explain with Stokes theorem that the field decreases like 1/r (with r the distance from the axis of the cylinder). Homework Equations Stokes theorem The Attempt at a Solution I was thinking of a circular loop...

Homework Statement Given an electric field in vacuum: Find the magnetic field under condition that |B| -> 0 as t -> infinity. Homework Equations I clearly have to use Maxwells equations to obtain the electric field here. Our equation for B has to satisfy them. More specifically Faraday's law...

I have been studying astronomy and astrophysics for about 2 years now, though on my own time and by my self. A recent question came into my mind, Can arctic planets exist close to their star? Now, in my understanding of planetary science, in order for a planet to be cool and close to the sun, it...

Homework Statement The following picture illustrates the passage of an electron a magnetic field. The magnetic field is trying to reverse the electron's velocity to the opposite direction. Calculate the force that the magnetic field is exerting on the electron in given time of ## t = 5...

I've got a question regarding the magnetic field of an electron, and wheter or not it has some form of "self inductance" or resistance to be put in motion. The magnetic energy per volume is equal to u= 1/2*μ*H2. Say I've got an electron at rest, then the energy of the magnetic field is zero...

Why in Madam Wu experiment more electrons are not in direction of magnetic field? See Fig. Why there is not four electrons in the direction of magnetic field and two in oposite direction?