Magnetism Definition and 974 Threads

Homework Statement Given two things spherical shells radii r1 and r2 with r2 > r1. The inner she'll is charged uniformly with a total charge Q1, while the outer shell with Q2. A) use gauss law to computer the electric field everywhere B) Use any method to calculate the potential everywhere...

Homework Statement Given two very long lines each is charged with linear density +lambda Coulombs/meter. The two lines are separated by a distance of d metres. A) show the electric field E, at any point along one of the lines due to the other line is E = lambda/(2 (pi)(epsolon o)(d)) (Note...

Does atomic structure require a magnetic force? I understand that in the world of people it is most appreciated, however, it doesn't seem to have a purpose in the atomic structure.

Hi all. I was wondering if time is dilated whilst traveling in a stable magnetic field that is generated by the object travelling, and if so, does this vary if you reduce or intensify the magnetic field? Also, what happens if the object is generating two opposing magnetic fields, would...

Homework Statement A particle of charge -q and mass m enterd magnetic field B at A with speed v1 at an angle alpha and leaves the field at C with v2 at angle beta.Then, a)alpha=beta b)v1=v2 c)particle remains in the field for time t=(2m(pi-alpha))/qB d)All of these Please see image below...

Hello community, I can't find an explanation for something and I thought I'd come and ask you. I'm studying for a test I have tomorrow and I came across a problem of a three legged steel core with 400 turns on the center leg, the magnetization curve is given, the first part of the problem asks...

Firstly, please note that I am talking about the period BEFORE electricity and magnetism were unified. So I am NOT seeking for answers based on Ampere atomic current model of magnets. I have read the following statement about the property of magnets at two different places. One from here: and...

It is known that Maxwell equations have the time reversal symmetry. I.e. by changing t by -t, J by -J (which can be understood as the charges going in the opposite direction when time is reversed, which makes sense), E to E and B to -B, the equations are still satisfied. However, it is also...

If a beam of electrons starts to accelerate from rest due to a uniform electric field in vacuum will the electrons feel any mutual repulsion or attraction? Will the beam first expand then contract? If yes, how does this happen? This was a question under magnetism head.

Homework Statement A plane electromagnetic wave travels upward. At t = 0, x = 0, its electric field has the value E = 5 V/m and points eastward. What is the wave's magnetic field at t = 0, x = 0? Homework Equations B=B init. sin(kx-wt) E=E inti. sin(kx-wt) E=cB The Attempt at a Solution I am...

Homework Statement Two straight rods 60 cm long and 2.0 mm apart in a current balance carry currents of 18 A each in opposite directions. What mass must be placed on the upper rod to balance the magnetic force of repulsion? ## \mu_0 = 4 \pi * 10^-7 ~\frac {T * M} {A}## ## g = 9.81 ~m/s ##...

There is a solenoid of a certain radius, carrying a certain current. I draw an amperian loop of radius greater than the radius of the solenoid. If I calculate the total flux through this loop it should be, 1) Non zero for an ideal solenoid (where the field outside the core of the solenoid is...

The Faraday's law and Lenz's law together give you, $$\xi = -\frac{\partial\phi_B}{\phi t}$$ or put another way,$$\vec{\nabla} \times \vec{E} = -\frac{\partial \vec{B}}{\partial t}$$. My question, I am just asking to make sure, the spatial dependence of ##\vec \nabla \times \vec E## will be the...

Hi, I am taking GRE Physics this year and I am preparing from Conquering GRE Physics book and I have covered everything in that book on Electricity and Magnetism (yet to study Optics and Waves). My question: How much from Griffith Electrodynamics book do I need to study? Or is the material in...

Hello! In 2010 Richard A. Lovett has published a photo from a ligthning-strike in the national geographic magazine, which shows significant x-ray radiation. Obviously a lightning-strike is an electrical current in air (and water).In electrodynamics an electrical current in metals generates...

The Faraday effect is a magneto-optical phenomenon caused by the interaction between light and a magnetic field. Is there a corresponding electrical-optical phenomenon, caused by the interaction between light and an electric field?

Hi, I am looking for the temperature dependence of the saturation magnetization of Fe. Any help?

1. Problem Statement: Find positions on the x-axis for the charges Q1 = -1 C and Q2 = +3 C so that the electric field is zero at x = 0. Homework Equations :[/B] I'm thinking I need to use Coulomb's law for this one. I'm just having trouble figuring out where to start. Coulomb's states E=kQ/r^2...

Homework Statement A magnetic field perpendicular to the plane of a wire loop is uniform in space but changes with time tin the region of the loop. If the induced emf in the loop increases linearly with time t, then the magnitude of the magnetic field must be proportional to: a)t^3 b)t^2...

How do I find out gauss from air core inductor 36mohm pumped with ~130amps 9ms long? http://www.parts-express.com/erse-25mh-14-awg-perfect-layer-inductor-crossover-coil--266-380 Greatly appriciated.

Homework Statement in the picture. Homework Equations F=ILcrossB Along with the original question, the other picture contains the solution with different numbers. I was just wondering why when finding the force on the wire instead of making dl= R*dtheta and going through the integration and...

Someone is asking me how much current in a loop of wire the diameter of the Earth to make the same level of magnetism the Earth has? I hope I am asking this correctly. TIA Clark

At first I was wondering whether antiferromagnetic materials exhibit magnetic hysteresis. From what I could read on wikipedia, I think they should, but for a very strange reason. Indeed, in the absence of any external ##\vec B## field, the magnetization of the 2 different sublattices have the...

Hello everyone, First off, i would like to apologize for any spelling errors. I am Portuguese and my english is going to be very simple. I am in the process of building something and i am reaching out to the physics community for help solving a problem. I am a CNC programmer and while i was in...

I recently saw the video of the frog being levitated with a big magnet. Would it be possible to flip the magnet over and use it to levitate a vehicle? How much energy would it take to levitate, say, a 1000kg vehicle above a dry lakebed?

Hello, I am unable to understand a certain (important) concept. We all know what the field lines of a permanent magnet look like. They go from north to south, and curve around the magnet. This direction (direction of the magnetic field) does NOT describe the direction of a force. And that's...

Hello, I have four questions. As it stands now, I don't have the necessary materials to test this myself, which is how I'd prefer to learn the answer. I still plan on doing this experiment for fun once I can acquire the necessary components. This deals with Lenz's Law. My goal is to maximize...

Theory explains magnetism in iron as a combined effect of magnetic moments of electrons. Now, what is confusing me is that valence electrons in iron are supposed to be free. The valence band and conduction band overlap. So, what kind of orbital and spin-ular momentum do these free electrons...

I'm looking for a book to help me understand a project I'm working on measuring the magnetocaloric effect. I'd like to understand a bit more about the link between magnetism and entropy. I'm a third year bachelor student so I've studied no quantum mechanics (yet), but I'm not against doing so if...

Homework Statement The problem asks to find the direction of the magnetic field at point P, which is at the center of 2 separate semi-circle wires that form a circle. The current in each wire flows in the same direction (to the right). I attached a picture below. Homework EquationsThe Attempt...

Homework Statement Two infinitely large conducting plates with excess charge 2Q and 3Q are placed parallel to one another, and at a small distance from one another. How are the charges 2Q and 3Q distributed? You may assume that infinitely large sheets of charge produce electric fields that are...

I understand the direction compnent of this question. But I don't understand where the magnitude of the induced current came from? I'm assuming faradays law wasn't used as there wasn't a change in magnetic field?

Hello! I'm currently working on a project that will utilize the phenomena of eddy currents to apply a braking force to a rotating disk. Some background on this project: My team was tasked to create a physical therapy training device to train patients in wheelchair propulsion at resistances lower...

These is there no induced current when the coils are stationary relative to each other? Isn't there still current (moving charges) in the the one on the left to cause a current in the one on the right when neither coil is moving?

As one know, the force on mangnetic dipole in magnetic field is $$ \vec F = (\vec p_m\cdot \nabla) \vec B_0$$, where B_0 -- external field. Let consider a some magnetic matherial with permeability \mu. The magnetization of matherial is $$M = (\mu - 1) H$$ (in SI units) and by deffinition $$M =...

I’ve seen a few places, here is 1 such link: http://physics.weber.edu/schroeder/mrr/MRRtalk.html I have a problem with how they represent the charges in the frame where the free charge is stationary and the charges are moving in the wire. This seems wrong for 2 reasons: 1. They show additional...

Homework Statement suppose a coil is placed in a changing magnetic field and the circuit is not closed will the current induce in the coil Homework EquationsThe Attempt at a Solution What I thought was that the current flows only in a closed circuit because it needs a potential difference...

I am currently going through a friend's Mechanics II notes and homework before I take the course at a different university next semester. I have a few problems that I am having trouble understanding and am posting here for help. 1. Homework Statement 1. A solenoid is on, Flux is Φ. 2. The...

We took today in a lecture gauss' law for magnetism which states that the net magnetic flux though a closed shape is always zero (Monopoles don't exist). The professor explained/proved it as following (Since it needs math theorems): Draw any shape. From the fact that any magnetic field line that...

This is question that can't really get a precise answer without significant modeling or experimentation, but I'm wondering what folks' intuition might be on an answer to the following setup + question: Suppose there is a steel tank made of steel pipe with walls about 0.25 cm thick, internal...

Why does current produce a static magnetic field, but a static magnetic field doesn't produce current? Specifically, why is one true, but the inverse not true? I can accept that each rule individually is just how the universe works... but it sounds so contradictory when I examine both together...

I remember reaching to the conclusion that changing the reference frame (Galilean transformation) doesn't give the same result in Electromagnetism interactions in high school, I searched for an answer and didn't look any further than knowing that SR solved this. Now I am back in an engineering...

Homework Statement Describe the magnetic field you would observe if two coils were connected with magnetic fields pointing in opposite directions. Homework Equations No equation The Attempt at a Solution If the magnetic field was pointing in opposite directions, would it mean that it would...

Homework Statement Determine the Full Width Half Maximum (FWHM) using the single coil equation and fitting parameters. The FWHM is the measure of how broad (wide) a signal is before it loses half of its intensity. In this case, its a measure of the distance spanned before the magnetic field...

Why does an iron core increase magnetism? Apologies if this more advanced than high school. EDIT: Disregard, found article on magnetic reluctance.

Homework Statement Homework Equations None, just right hand rules. The Attempt at a Solution Can anyone verify that this looks alright? These things are so confusing! Thanks :)

My question is magnetism energy or force? On the one hand, it is energy because it can be transformed to say electricity, on the other hand is the force because, say, in the alternator, it transfers the mechanical to the electric energy .

I appreciate that under standard conditions small (c 5mm) plastic particles are apolar and thus non-magentic. However, can conditions be created under which such particles could exhibit polarity?

What is the name given to the path along which a free north pole end of a magnet would point? Name of a "path"? The name is magnetic field line? north pole?

So i was just wondering if a satellite's circuitry could be affected by the Earth's own magnetic field inducing a current, if it was moving through it quickly enough (the space station for example), and how it might mess with it? Also considering a satellite is a big hunk of metal, could passing...