Magnetism Definition and 974 Threads

Homework Statement 2. Homework Equations FB = ∫I ds×B The Attempt at a Solution My first guess was that it would not move at all. I understand that there is an induced magnetic field in the opposite direction but wouldn't the induced field produce a current counterclockwise, which, since...

Hey, is it possible to have a cylindrical ring (made of permanent magnet) and a magnetic sphere sitting inside it and staying in one place without touching the inner sides of the ring and not falling through? The object doesn't necessarily have to be a sphere. If it would work with any other...

Lets suppose that I have a magnetic dipole moment at (0,0,0) pointing to the Z axis, and in the position (X,Y,Z) in the space, I have a Hydrogen atom, I would like to know the exact interaction between the magnetic field created by the magnetic dipole moment in (0,0,0) and the magnetic fields of...

Homework Statement A small circular flexible loop of wire of radius R carries a current I. It is placed in a uniform magnetic field B. The tension in the loop will be double if A) I is doubled B) B is halved C) r is doubled D) both B and I are doubled. Homework Equations The Attempt at a...

I need a charged particle trajectory in crossed E and B that is a cycloid in the x-y plane. This part is simple enough, but I want the trajectory to be parabolic in the x-z plane. The images will help explain what I need. The left image shows the shape I want to achieve, and the right image...

Homework Statement A long, straight wire lies along the z−axis and carries a 4.20 −A current in the +z−direction. Find the magnetic field (magnitude and direction) produced at the following points by a 0.400 −mm segment of the wire centered at the origin. Homework Equations ## \vec B ## = 2...

In Berkeley Physics Course (Volume II) on Electricity and Magnetism: https://www.scribd.com/doc/128728926/Electricity-and-Magnetism-Berkeley-Physics-Course-Purcell ...Purcell discusses the invariance of charge (Section 5.4), the electric field measured in different frames of reference (Section...

Hi, I'm trying to do a very simple analysis on Simulink where I am applying a speed to a Permanent Magnet Synchronous Generator with a purely resistive load. I'm not familiar with PMSGs so the results I'm getting don't really make any sense to me. Could anyone go through some simple design...

I'm having some confusion about the creation of magnetic field lines. How I understand it so far, is that a magnetic field is basically an electric field viewed from a relative point. I don't have a great understanding so far, as I just started to learn about it, but I've learned that objects...

Does a rotating magnetic field possesses angular momentum in the direction of rotation? I suppose this comes down to a broad question about the physical nature of fields in general. I love the Einstein-de Haas effect, where an iron core spins in the opposite direction of the induced spin...

<Moderators note. Moved from the quoted thread to avoid detracting> Newton third law does apply in magnetism, and this is proved by applying the conservation of momentum principle. This will be clearer when the causes/origin of the magnetic force is understood as described in the work "Two new...

If a toroidal ferrous core has a number of windings round it and a DC current going through them, would this magnetic core be subjected to a 'shrinking force'? To phrase it more clearly, if the toroidal core was compressible, would it actually get compressed? On the one hand, since the...

I have a rather odd question that delves outside of the realm of reality just a bit. Recently, I've had a bit of an obsession with designing ludicrous weapons. My current venture is a little bugger I call the 20MM Magnetic Accelerator Rotary Cannon. The MARC20 for short. It's an eight barreled...

I'm major in chemistry my undergraduate.. and not good at Physics, Solid states... etc. I know pure graphene has two sub-lattice because it has two carbon atoms.. and something basic properties. then, why perfect graphene(no vacancy) is in nonmagnetic?

I have been trying to search for answers on the Internet, but to no avail. For induced magnetism, i understand that a magnetic material can turn into an induced magnet under the influence of a magnetic field. However, i do not understand how to magnetic poles are determined. Suppose a perm...

Homework Statement For my extended essay as part of the IB, I am investigating the effect of changing the distance and the number of stationary ball bearings in a Gaussian gun. I was hoping to look at the energy transfer during each stage of magnets and therefore calculate the efficiency...

Hello everybody! I am excited to be part of this forum. It's the first time for me. I am 41, from France and with my sons (9, 7 and 6) we love physics. I have studied economics and discovered my interest for physics only a few years ago. I try to learn things by myself with videos from You tube...

Knowing that Gauss' law states that the closed integral of e * dA = q(enclosed)/e naut, how would you find exactly what A is in any given problem? I know it varies from situation to situation depending on the geometry of the charge. For instance, I know that for an infinite wire/line of...

I have a doubt on this calculation of magnetic field in presence of displacement current. Consider a capacitor of radius ##R## and with plates at distance ##d## being charged: there is a displacement current in it. Suppose that I want to calculate the magnetic field ##B## at a distance ##r <...

Hi, I read a chapter about the Heisenberg-model, and then something about the Hubbard-Model. The Heisenberg-model just shows, that neighbouring spins allign antiparallel if J<0. The Hubbard-Model says, that there is a hopping probability t and an Coulomb replsion, so that a material becomes...

How magnetism acts on earth?

We have a permanent saturated magnet. And a coil wound around it. The current produces magnetic field in same direction as the magnet. Now we know that the energy of magnetic field is proportional to the square of the magnetic induction. E1=kB12 E2=kB22 Etotal=kB12+kB22+2kB1B2 We have an extra...

since graphite conducts. if spiral shape is drawn with pencil on the wall (thick , dark lines) will a voltage difference appear between inner and outer end of the spiral when a varying magnetic field is switched on, normal to wall

Homework Statement Find the force of attraction between 2 magnetic dipoles a distance r apart. Both dipoles point to the right. Homework EquationsThe Attempt at a Solution All I need help with is figuring out how to determine if the force is attractive or repulsive between the 2 dipole...

Homework Statement A cylindrical conductor of radius ##a## has a hole of radius ##b## and there is a current ##i## uniformly spread inside the conductor. Calculate the magnetic energy of the conductor. Homework Equations $$U_{m}=\int_{Volume} \frac{B^2}{2 \mu_0} dV$$ The Attempt at a...

Homework Statement Homework Equations ##\oint \vec{H} \cdot d\vec{l} = I_{free,enclosed}## ##\vec{B} = \mu_0 (1+\chi _m)\vec{H}## The Attempt at a Solution I found the magnetic field inside to be ##\vec{B} = \mu_0 (1+\chi _m)\frac{Is}{2 \pi a^2} \phi##. But why can't I use the same equation...

Homework Statement This is a theoretical question, one I'm not sure about. It just randomly popped into my head. Say there is a jumbled wire, one in a glob shape but not overlapping. (Like a deformed circle, or maybe just a rectangle). Assuming we are in a place called "physics utopia" where...

I'm currently in conceptual phase of designing a coil gun. Thinking back to my physics 2 class-- and some of my independent studies-- I understand an EMF produced by a solenoid with current through the wires of it is strengthened significantly by a ferrous core, as seen by the classic experiment...

Homework Statement We have two coils of copper wire, drawn below. One has a battery connected to it. The other one has a galvonometer connected. If the coil with the voltage is moved closer as shown in the picture, with considerable velocity, what direction will the current induced on the other...

Dear all, I'n an EE that finished his degree more than 10 years ago. I wanted to refresh my Electricity and Magnetism knowledge. I bough Purcells book some weeks ago (https://www.amazon.com/dp/1107014026/?tag=pfamazon01-20) and I'm kind of struggling through the maths (Vector calculus). I've...

Homework Statement We consider a sphere of radius R which carries a uniform surface charge density \sigma and spins with angular velocity \omega around a diameter. We use spherical coordinates (r, \theta, \phi) with origin at the centre of the sphere and the z-axis along the rotation axis...

I read a paper on how a magnetic field of 4 T was used to break the van der Waals forces of an HeO molecule with a binding energy of 11.2 cm-1. I'll put the link to my original post below. Can someone tell me how this energy was measured? Your assistance is greatly appreciated...

Recently I did an experiment where I dropped a magnet through a tube that was surrounded by a coil, and I hoped to investigate a factor that would affect the current induced (Faraday's law). I chose to study the effect that changing the cross-sectional area of the wire had on the induced...

Hello! I'm looking for some help regarding magnetism and how it might work (or be fictionalized) in regards to a "magic" compass. I have two questions. Please excuse my complete scientific ignorance :) In my story, our young hero has a compass. The compass needle just spins in endless...

What happens if I have a permanent magnet outside an ideal solenoid? Does the permanent magnet rotate until the system reaches an energy minimum in its magnetic fields? Or does the permanent magnet fail to rotate because the magnetic field of the solenoid does not reach the magnet? Wouldn't...

Have any experiments on the Casimir effect tried what happens if the plates are temporarily magnetized when they are pulled together by the effect? E.g. measurements of what happens to passing laser beams and the like?

Why must steady currents be non-divergent in magnetostatics? Based on an article by Kirk T. McDonald (http://www.physics.princeton.edu/~mcdonald/examples/current.pdf), it appears that the answer is that by extrapolating the linear time dependence of the charge density from a constant divergence...

For a start, I must say that I'm just very interested in physics and maths but have no real education in these subjects. Does magnetism behave like other forces? Is the speed of the magnetism limited by lightspeed? Is it a wave or a particle, or both like light. Now for gravity, we have...

Let's say I have a spherically-uniform black-body radiator. It is losing energy, and therefore some of its mass, at a particular rate. From the frame of reference of the radiator, it has no momentum, but it has a changing amount of energy. From its frame of reference, the pressure on the...

Hi, I have been asked how many times a magnet can magnetize a magnetic material before itself get demagnitized. The example in hand was the question about a strong neodymium magnet that accidently ruined a ferrite magnet. The next question was then why this neodymium magnet appears to not lose...

Electromagnetism is divided into two parts Electrostatics Magnetism Therefore I want to know what are the main difference between electrostatics and magnetism with their examples in layman terms because I am not at all introduced to this concept but I want to know the general concepts related...

1) If I vary charge densities, but keep current density constant, do I get any sort of electromagnetic wave? 2) If the answer to question 1 is no, then if I vary charge densities, but keep current density constant, could I conceivably have a two isolated "open circuit" current elements of...

So sorry to post what seems to be a well worn question. So the 4 forces of nature work by "particle exchange" ? Yes we understand the maths of "Fields" and we have the elegance of Maxwell and Newton/Einstein and these mathematical descriptions lead us to force exchange particles which can...

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...

I heard that Griffith's Electrodynamics is at a similar level of Purcell's book on electricity; is it fine if someone goes into a graduate level electrodynamics book right after Purcell?

Homework Statement Homework Equations Biot-Savart's law and ampere's law expressing B = mu0 * I / (2 * pi * r) The Attempt at a Solution [/B] I know that for the first drawing, we have magnetic fields going into the page from both of the wires, and we have them being (infinitely) long, so...

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 <...

A free electron gas would have zero magnetoresistance; it takes two carrier types to get ordinary magnetoresistance, which is always positive in sign. Beal-Monod and Weiner explain the negative magnetoresistance found in very dilute magnetic alloys, in terms of the spin-flip scattering of...

Hi guys, I am having quite the struggle finding a good resource to explain the difference between the magnetic force associated with moving charged particles (Lorentz Force) and just the regular force exerted by a magnetic field on a magnet or ferromagnetic material. I am trying to apply this...

Hi. These things can be used to magnetize/demagnetize tools, e.g. screwdrivers: How do they work? I'm particularly interested in the demagnetizer part. How do the field lines look like? And why is there this stair-like structure in the upper hole?