Magnetism Definition and 952 Threads

Hi all, I read the FAQ so please take into account that this is NOT a perpetual motion (free energy or whatever) question but a theorical case that puzzles me. I read that magnetic fields have an infinite (but decreasing) range. What bothers me is this : let's put a magnet and a iron far...

Homework Statement A bar magnet is held stationary (with respect to the loop of wire) at the centre of the loop with the North pole sticking out one end and the South pole sticking out the other. What happens to the size of any EMF induced in the loop once the magnet has been replaced by a...

Homework Statement I am asked to show that B = \frac{\mu_0Q\omega}{2\pi R^2}[\frac{R^2+2x^2}{(R^2+x^2)^{1/2}}-2x] simplifies to this B \approx \frac{\mu_0}{2\pi}\frac{\mu}{x^3} if x>>R where \mu is the magnetic dipole moment for a disk spinning with angular velocity \omega, which is \mu...

I am supposed to graduate next year but I just realized I have left Electricity and Magnetism off of my schedule. I'm afraid to add it because I feel like I am already taking enough and I am wondering if instead it is common or likely to just take the undergrad elective in graduate school. I...

Homework Statement Three long parallel wires are a distance L = 5.71 cm from one another. (Looking at them, they are at three corners of an equilateral triangle.) The top wire has a diameter of 1.8 mm and is made of copper; it is suspended in air due to the magnetic forces from the bottom two...

Homework Statement As the bar magnet (see attached diagram) leaves the loop of wire, it experiences a force opposing its exit. I understand why, according to Lenz's law, a force would oppose the bar magnet's exit. I don't understand, however, what causes the force. In this case, the force is...

Why flowing current in wire creat magnetic field...if anybody say this is because of spin quantum number,... So i just want to say spin quantum number is because of wave nature of electron.i just want to know what effect of dual nature of electron on magnetic field.:rolleyes:

Hi, so I've just started learning about physics and I get the gist of most of it. I understand motion, torque, energy, light, radioactivity. But there is one topic that absolutely stumps me. Electricity. Can someone explain to an absolute moron like me what it is? It seems like everyone around...

In a recent Physics lab, I experimented with the magnetic field generated by two Helmholts coils. I used a Hall probe, and some software created by the Grad students to plot the field strength against probe position in a series of configurations. I understood almost all of the lab, I...

Hi all,I have been struggling mightily through Purcell's book on Electricity and Magnetism, but chapter 5, which deals with the SR explanation of magnetism has me somewhat confused. Suppose we take the following scenario: In the Lab frame, F, electron 2 (e2) is moving towards the right...

Hi, I am new to the forums and thought of asking this question convenient right here. So, I was wondering that we have many novels explaining Astronomy and Particle physics for non physicists or physics enthusiasts. For example books on Biographies of say Einstein go a little deep into his...

Homework Statement 2. Homework Equations ##\mathcal{X}=\frac{\mu^2_BNg^2_j}{3k_BT}J(J+1)=\frac{C}{T}## ##M=\mathcal{X}H## The Attempt at a Solution [/B] ##Fe^{2+}## has a value 4 of J from hunds rules. So I know what the curie factor for iron is ##M=\frac{m}{V}=\frac{HC}{T}##...

There is an analogy between electric and gravitational potential energy. ## U_g = \frac {GmM}{r}## ## U_e = \frac {kqQ}{r}## What is the analogous formula in magnetostatics? Thanks...

Look, I found that there exist two kind of electric current: conventional flow and electron flow. I have read that in every situation I have to use the conventional flow, however I'm going to work with electric circuits using copper wires. In solids, only negatively charged particles (electrons)...

A changing electric field produces magnetic field and vice versa.Does that mean that this process will carry on forever?Think of a circuit with a capacitor.The magnetic field due to the current at a point on the wire(with Ampere-Maxwell law).But current was changing with time,so it also meant...

Hi Is there any fluid that is a permanent magnet at room temperature? (Ferrofluids do not retain their magnetic effect hence temporary). Thanks

Hey Is there any liquid available that is magnetic at room temprature? I know that liquid helium is magnetic but at very low tempratures not at room temperature. Thanks

Homework Statement (See image) a closed circular wire A lies in the plane of the wire B in the circuit. Deduce the direction. Of the induced current in A when (A) the switch is closed (B) the switch is opened (C) the wire A is raised out of the plane of the paper. Homework EquationsThe...

I have been trying to come up with a good question for my Ib extended essay which is a 4000 words essay about any physics topic of my choice. However, with this topic I need to come up with an experiment to further investigate this topic and write up an analysis and conclusion. I am really...

Homework Statement What is the magnetic-field energy in a 10.0cm3 volume of space where B = 3.50T? Homework Equations u = B2/2μ0 The Attempt at a Solution Using the equation I got an answer of 4.87*105 J/m3 which is incorrect

I have a question about magnetic repulsion. Suppose I have a permanent magnet (axially magnetized) placed on top of the iron core of an electromagnet. I want to switch on the elctromagnet to repel the permanent magnet. (Please assume the permanent magnet is contained in some kind of tube that...

Hello Madams and Sirs. Newby here. I'm in the middle of engineering a new product for the percussion market which involves the use of a few magnets. Question is thus. What is the formula to determine the applied force of a given strength magnet or magnets over a given distance.? The apparatus...

For a module I recently ran a computer simulation to determine the temperature at which a material underwent a ferromagnetic to paramagnetic phase transition. However, I'm not really sure what the applications are of knowing this are. Obviously if you wanted the material to retain its permanent...

Do electrons attract to each other like permanent magnets?

If a neodymium magnet sticks over a steel plate and you want to separate them, it is advised to apply force such that the magnet slips over steel plate. So I was just wondering what would be the quantified decrement of this force as compared to the case when force is applied axially to separate...

Homework Statement Two horizontal parallel conducting rods are connected such that a conducting crossbar free to slide along them has a constant current I running through it (Figure 1) . The rods are separated by a distance ℓ and are in an external uniform magnetic field of magnitude B directed...

Homework Statement A long wire carrying a 6.0A current perpendicular to the xy-plane intersects the x-axis at x=−2.0cm. A second, parallel wire carrying a 3.5Acurrent intersects the x-axis atx=+2.0cm. At what point on the x-axis is the magnetic field zero if the two currents are in the same...

I was interested to know as magnetism works in space. Can magnets be used to bend space-time? If this is possible may be able to time travel.....

So I was surprised to notice that my plastic shopping bag was able to actually push and pull tap water significantly far with its electrostatic force. But when I put a magnet near the water nothing happened. What makes the electrostatic force so different from magnetic force; isn't it just two...

For diamagnetic materials, when an external magnetic field is applied, the electrons having orbital magnetic moment in opposite directions spped up. how does this happen? The direction of magnetic momwnt is given by right hand thum rule. If there is an electron revolving in anticlockwise...

I don't think I've fully grasped the underlying ideas of this class, so at the moment I'm just sort of flailing for equations to plug stuff into... Homework Statement Show that in the mean field model, M is proportional to H1/3 at T=Tc and that at H=0, M is proportional to (Tc - T)1/2...

(1) I previously learned that a constant magnetic field causes a force on any electrons within its range. Clearly, this force would cause electrons to move. Isn't this creating a current? (2) However, now apparently I am told that the only varying magnetic fields can create a current. I.e...

I am having difficulties writing my damped oscillations lab report. We were asked to write a short essay on eddy currents (creation,direction advantage and disadvantage) and their relationship with torsion pendulums. Also,we have to explain if the copper wheel in the torsion pendulum could be...

I know we can represent it two different ways. First: \mathbf{B} = \frac{\mu_0}{4\pi}\int_C \frac{I d\mathbf{l} \times \mathbf{\hat r}}{|\mathbf{r}|^2} If we open up unit vector, then it becomes: \mathbf{B} = \frac{\mu_0}{4\pi} \int_C \frac{I d\mathbf{l} \times \mathbf{r}}{|\mathbf{r}|^3} I...

hello I want to calculate the force exerted between two electromagnets, based on their current I want to hold two metallic discs together, how much force can I exert between them with electromagnetism? is this something simple? any hint? thanks!

If heat is the nemesis of magnetism how does the sun maintain it's magnetism? Does the sun produce more magnetism than can be destroyed by the heat. Thanks

I have found an equation which gives the EMF generated in a coil when a magnet is spun near it, the equation is given as: E = FNAω × 10-8 volts. Where F is the field of the sample perpendicular to the axis of roation, N is the number of turns, A is the effective area of the coil and ω is the...

The only books I've been able to find are fairly old and are not written very clearly. Would someone be able to put it into A-level terms? I'm not worried about knowing any of the complicated mathematics behind it, only the conceptual side. Although if anyone fancies giving both then that would...

hello can you give me some idea of the quantity of magnetism, electrism and forces involved? for example, what is the torque in Nm or the Joules, that I can generate, via a motor perhaps, from a 220V AC motor? I want to know how much magnetism and electrism I need to rotate a disc that poses...

for example say I were to roll a magnetic ball down a hill and placed another magnet at the end of the hill, would the magnetic ball hit the magnet with more force than a non magnetic ball. This question is for my science fair, all people answering must be prepared to answer follow-up questions...

I'm trying to understand how to calculate the strength of the magnetic field generated by a current loop. What I know so far is: When a current moves around a loop of wire it generates a magnetic field which looks a bit like that of a solenoid, only not so concentrated through the center of...

I understand that only three elements are magnetic: Iron, Cobalt and Nickel, iron being the strongest. This element in it's purest state is un-magnetized, right? Composed of a bunch of crystal magnets or domains. So if you have three ores of each element at their purest form they won't...

Homework Statement I am trying to answer the question: "An electron is accelerated in an evacuated chamber. Sketch lines that illustrate how the magnetic field produced by the electron will vary with time. "Homework Equations F=q(v x B) The Attempt at a Solution I cannot find a sketch of this...

I am doing a physics project whose purpose involves describing the physics behind a toy. The toy I have selected is a "decision maker" which is composed of a pendulum which has a magnetically charged ball on it that swings side to side, while having a force exerted on it by magnets which change...

how can i find data for Earth magnetism for the period 30,000 years to today, is it possible to control magnetism forces thanks

Hi I'm currently reading up on magnetism and its relation to currents but there's one thing that frustrates me and the textbook doesn't seem to elaborate on it. I understand that a current produces its own magnetic field (and we use the right-hand rule to determine this), it also makes sense...

I found two ways to solve this problem, but I get two different solutions, it's confusing because I can't see the flaw in wrong solution. 1. Homework Statement Long cylindrical inductor of diameter D1 and inductance L1 is connected to battery and creates magnetic field B1. Inductor is then...

Homework Statement Experiments carried out on the television show Mythbusters determined that a magnetic field of 1000 gauss is needed to corrupt the information on a credit card's magnetic strip. (They also busted the myth that a credit card can be demagnetized by an electric eel or an eelskin...

hello! If I rotate a metallic cylinder that is a permanent magnet, it will generate electricity in a wire next to it? for how long it will generate electricity? forever? or it phases out as the magnetic energy transforms to electricity? how long it will last approximately? thanks

Homework Statement Two long, straight wires with a current of 8.2A on the left and 9.3A on the right flowing in the same direction. The distance between the wires is 8.8 cm. a) What is the magnitude of the force per unit length between these two wires both in length and direction b) How far to...