Magnetism Definition and 952 Threads

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?

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...

I'm trying to get a handle on what magnetism really is. I know that charge in motion generates a magnetic field. I know that objects and particles can be permanent magnets when the magnetic fields of their elementary particles "line up." But how do stationary elementary particles have the own...

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

Hello PF! I am writing a scientific report about magnets, but have really no clue how magnets actually work? Research has yielded a few ideas, specifically from here and here. However, sometimes (in iron, nickel, and cobalt for example) you’ll have one or more un-paired electrons. The...

Hello, I will be taking a second course on electromagnetism and I want a book that bridges the gap between Griffith's book and Jackson's book. I have come across Panofsky's book and Nayfeh's book but I don't know which one is better. Any opinion for these would be much appreciated Thanks!

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...

I've done some research on Google but have found no of relevant information. I basically want to create a rope effect using magnetism. The objects will ideally maintain a certain distance from one another - the distance can vary to some degree - but must not be attracted too closely nor...

I am trying to calculate the forces between a simple sphere neodymium magnet on other iron surfaces and magnets. I did a lot of research but still not sure what equation to use or how to apply them. I found the following equations here (https://en.wikipedia.org/wiki/Force_between_magnets) F =...

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?

Ok, I've spent lots of hours browsing the web and the library and still this question is burning. How can i calculate, whether it be experimentally or theoretically, the " pole strength" of a magnet. (I have read about the experiment where you divide the work it takes to turn a magnet around a...

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...

I've read in various places that magnetism can be explained in terms of the effects of special relativity. However, all of the explanations of this only mentioned the case of current flowing in a wire. Can special relativity explain the magnetism of free flowing electrons and other moving...

This is a graph for a magnet falling through a coil, it shows the p.d induced in the coil (the induced emf) when the magnet enters and then shows the induced emf in the coil when the magnet leaves. My question is why does the p.d appear to change direction? (i.e why the positive and negative...

Say you have a coil connected in a closed circuit. You then move a magnet inside of the coil and it remains stationary inside of the coil. Is the magnet, even though it is stationary, still inducing an emf in the coil or is it not? I'm guessing it doesn't induce an emf in the coil because...

If I took a charged particle and accelerated it, that acceleration would have an effect on charges potentials, allowing for the radiation of electromagnetic waves. This acceleration would be local to a point in spacetime and the observed potentials would depend on the frame of reference of the...

I have recently studied about relativity being the reason for magnetism. The example given was about a magnetic field generated from current down a long wire. When two such wires with current in the same direction were parallel to each other there was an attractive force between them because...

In classical physics, when electric charges accelerate, they are expected to radiate. Electromagnetic waves, are by their nature the result of changing electric and magnetic fields. But is it possible to have acceleration of charges without having changing electric and magnetic fields? One...

So in conductors, the electrons will distribute themselves to the surface via repulsion forces. But why do we say that the electric field inside is zero? If I put a positive charge inside, clearly it will move in some direction from the electric field of generated from the electrons. Also, are...

Hey! 1. Homework Statement One must simply calculate the magnetic field at a distance s to the wire, which carries a steady current I Homework Equations Should I write the point vector as: \mathbf{r} = s\hat{s} + \phi \hat{\phi} + z \hat{z} or \mathbf{r} = s\hat{s} + z \hat{z} ? The Attempt...

Please help! I have recently completed an experiment on transformers, using a step up transformer. I am aware of all the theory that shows that in a step up transformer, the induced voltage should increase and the induced current should decrease. However, in my experiment, my hypothesis is not...

First of all hello everyone, I'm a recent graduate and now I am a mechanical engineer (WEEEEE) and wanted to embark in a project that involves creating artificial forces (Newton's third law kind of forces). The project basically must have something to counter forces exercised by a hand, i.e. if...

So from Faraday's law, a change in the magnetic flux will induce an emf on a loop of wire. { \phi }_{ B }\quad =\quad BA\\ { \varepsilon }_{ ind }\quad =\quad \frac { d{ \phi }_{ B } }{ dt } (in this case a perpendicular field) From these equations, it looks like the only way to induce a...

Homework Statement Homework Equations B = μi / 4πR is the equation for a semi-infinite straight wire The Attempt at a Solution I know that for each situation in a,b, and c I would use the equation I listed above, but I am not sure what I would plug in for R for each situation.

Hi people! I am a high school rising senior who is looking to self study electricity and magnetism over the summer. Particularly, my aim is to take the ap physics c electricity and magnetism exam as a result of this self study but also to realize if I want to work with hardware/electrical...

Can someone please help me out with this practice test and provide explanations?

Hi! This might be a dum idea but here goes. Say you have 3 items. One weak magnet and two ferromagnetic materials of different susceptability. The magnet is strong enough to saturate the first material bot not the second. But since the saturated field in the first material is larger than that...

Homework Statement **Question** Is the magnetic field directed into the page or out of the page?Homework Equations Right Hand Rule The Attempt at a Solution My index finger is pointing downwards, and since the magnetic force is towards the right and this is an electron (negative) my thumb...

If photons are part of a magnetic field like electrons, which electrons can be read with an amp meter, what can measure or count photons? Electrons are not counted but the magnetic field changes when more current flows and the ammeter reads a change in the magnetic field. What type of light are...

Homework Statement The figure shows a cross section across a diameter of a long cylindrical conductor of radius a = 2.92 cm carrying uniform current 151 A. What is the magnitude of the current's magnetic field at the center of the conductor? Homework Equations Biot-Savart's Law The Attempt...

4/23/2016 = 5:37:05 How do you explain this? Instrument Failure? Pole Reversal? Source: http://iswa.ccmc.gsfc.nasa.gov/IswaSystemWebApp/index.jsp?i_1=581&l_1=568&t_1=77&w_1=501.333&h_1=334.333&s_1=2016-04-23 09:27:51.0_1_300_3&i_2=578&l_2=17&t_2=159&w_2=543.333&h_2=507.333&s_2=2016-04-23...

For AP Physics or Chemistry, how do we explain the origin of magnetism, and diamagnetism? Saying that "Well, it's a quantum mechanical effect" or "it is a relativistic effect" isn't much help in explaining it's origin. Are there semi-classical explanations or analogies, that high school seniors...

I'm not sure how magnetic field strenghts and dipoles work. I know that the strenght decreases by 1/r^3, but - isn't magnetic field strenght a constant inherent to the magnet? - if it is not constant, what is? - how is all this related to magnetic damping force?

Homework Statement I have attached a picture that details the problem. This is my practice test and I have no clue what I am doing wrong. Essentially a loop of wire is moving in constant velocity into a magnetic field. The magnetic field lines are pointing into the page. The problem is...

i'm confused with N , it says that is the number of turns per meter , but is the meter the length of the wire or the coil height ?

Homework Statement A wire is moved with constant velocity such that the motion is perpendicular to the length of the wire in a region containing magnetic field perpendicular to the plane of motion. The wire has a resistance R. Will thermel energy be generated in the wire? Homework Equations...

Homework Statement A metal sphere of charge +6μC is surrounded by a metal shell of net charge +6μC. Which of the following diagrams represents the electric field lines of the system? Homework EquationsThe Attempt at a Solution The correct answer provided by my teacher is a figure with 12...

I decided to simulate this scene in Lord of the Rings for a project in school with the purpose of calculating the "real" mass of the One Ring. I've done the experiments according to this principle sketch but I have some troubles with calculating the magnetic force that the copper coil is...

The magnetic field has no net source or sinks i.e. number of sources are equal to the number of sinks. Can a scalar field also have no net source? Or a source is required for a scalar field?

If a magnet is cut in half, it is still a magnet (dipole). If the magnet is continuously cut in half until it is only an atom, it still remains a magnet. My question is, what part of the atom generates the magnet field? I understand that magnets form primarily from the spin and angular momentum...

Does anyone know a good program, even a demo for modelling how magnetic fields influence each other? I'd like to run thru some exercises with actual numbers on wjhat kind of field patterns can be made by arranging magnets of same or different strength in different configurations. I should...

Homework Statement A square wire loop 12.0 cm on each side carries a clockwise current of 15.0 A Find the magnitude of the magnetic field at its center due to the four 1.30 −mm wire segments at the midpoint of each side. Homework Equations B = (μ0*I)/(4π)*(2a)/(x√(x^2+a^2)) The Attempt at a...

Homework Statement A square wire loop 12.0 cm on each side carries a clockwise current of 15.0 A Find the magnitude of the magnetic field at its center due to the four 1.30 −mm wire segments at the midpoint of each side. Homework Equations B = (μ0*I)/(4π)*(2a)/(x√(x^2+a^2)) The Attempt at a...

Homework Statement A bar magnet floats above another bar magnet. The first has mass u1 and magnetic moment m1=m1k^ and is on the ground. The second has mass u2 and mag. moment m2=-m2k^ and is a distance z above the ground, find z 2. Homework Equations I assume I need to calculate the magnetic...

I am still a bit puzzled by this video: Does this mean that force exerted on an electrically charged particle facilitated by moving through magnetic field B is due to special relativity, and not virtual photons acting as magnetic force carriers? Thanks

Homework Statement A circular uniform laser beam has a power of P = 3.2 mW and a diameter of d = 8.5 mm. The beam is a form of electromagnetic raditation with both electric and magnetic field components. (a) Calculate the intensity of the beam in units of W/m^2 (b) Calculate the energy (delta...

Homework Statement Suppose the electric field between the plates P and P' in the mass spectrometer in following figure is 1.89×104V/m and the magnetic field in both regions is 0.668 T. If the source contains the three isotopes of krypton, 82Kr,84Kr, and 86Kr, and the ions are singly charged...

Hey all, I am a graduate student (in chemistry) working on oxide crystals. Our group has a SQUID magnetometer which we use for magnetic property measurements. The other day a fellow student and myself got into a discussion about LS coupling and crystal electric fields. I know that CEF will...

I'm from a country in Africa where I didn't have the privilege of learning the Standard Model, so I'll try and rephrase my question here: https://www.physicsforums.com/threads/why-is-the-electromagnetic-field-not-a-charge-field.857927/#post-5384284 In a way where my ignorance doesn't outrage...