Magnet Definition and 868 Threads

A magnet that won't stop spinning?? what happens if a horseshoe magnet is fixed to a a coil such that there is a constant field through the coil?? The initial torque due to the field will spin the coil,but since the magnet is connected to the coil,it will keep sending a field through the coil...

Hi, I wanted to calculate the magnetic field of a cylindrical magnet at a point P (r,ɵ,z). The magnet can be at the origin or anywhere convenient. Preferably the axis of the magnet is aligned with the z axis. The magnet is of radius r_m and height h_m. The remanent flux density of the...

I was trying to find the value of the magnetic field at a distance x from a rare-earth magnet and came across this equation: B=\mu_o*2\mu/(4\pi*d^3) Does anyone happen to know the magnetic moment, \mu, of a rare-earth magnet? Nothing specific, an order of magnitude value is fine. Thank...

Is it possible for one magnet to attract another over a distance of 1m? To specify, if magnet 1 was at point A on the East side of the ruler, and magnet 2 was stationary at point B on the West side of the ruler. Could magnet 2 attract magnet 1 so much that both were bound together at point B on...

Hi, I've just completed a prac, where a beam was placed into a solenoid with a current flowing through it, causing a force to exerted down and I balanced out the force by placing weights on the other end in the effort of calculating the magnetic field strength. Anyway, one of the short answer...

Homework Statement An alien civilization has crossed the galaxy to invade the Earth and enslave humanity, again. Their attacks have been successful so far because their assault troops are equipped with handheld weapons that project beams of charged particles (protons & electrons) at very...

I am trying to do a pre-lab assignment for an introductory calc-based E&M course, and it involves the calculation of a magnetic field due to a bar magnet. My first inclination was to use the B = (mu/4pi) * (q (V x R ) / R3) equation, but I am quite certain that this is not the correct...

Greetings, I fabricated a PMA using vertically stacked stators and rotors. I tested the unit on a lathe and was able to gather the following data at different RPMs. The design uses the flux lines from both ends of the magnet. This configuration allows the stators and rotors to be stacked...

I'm doing a lab write-up for physics 2. The experiment is about the title, a bar magnet being dropped through a solenoid. I have to explain four graphs that plot the change in emf (y axis) vs. time (x) axis. There are incoming and outgoing peaks on these graphs. I have to tie these results...

I'm doing a lab write-up for physics 2. The experiment is about the title, a bar magnet being dropped through a solenoid. I have to explain four graphs that plot the change in emf (y axis) vs. time (x) axis. There are incoming and outgoing peaks on these graphs. I have to tie these results...

new guy here with a simple question. if i were to coil 10 turns of 14 gauge insulated wire around an 1/8" round x 1" long neodymium magnet, then wire it in parallel to a second magnet with 20 turns of the same gauge wire, what kind of change could i exspect in the second magnet if i spun a...

a steel top which remains upright when not spinning has an electromagnet pulling on it from the side. Q=does it make any diff how much the emagnet moves the top sideways if the top is spinning or not? Please dirregard the friction factor at the bottom point of the top. thanx

Hey guys, Im trying to design a electric gear shiftier for a motor bike. Basically I require about 200N of force to change gear with a 10mm throw (in both directions). I would like to use a tube neodymium magnet. (23mm diameter 25mm high with a 5mm hole throw the centre with a N48 grade) What I...

Hello everyone. There is a little project I could use some help with. I would like this done in a spreadsheet, so I can mess around with different values. The Problem: On one hand, I have a permanent magnet and, on the other, I have a ferromagnetic object. I want to find out the force...

Hey guys, Im trying to design a electric gear shiftier for a motor bike. Basically I require about 200N of force to change gear with a 10mm throw (in both directions). I would like to use a tube neodymium magnet. (23mm diameter 25mm high with a 5mm hole throw the centre with a N48 grade) What...

Homework Statement 1. compare the induced voltage of the attached magnet ( two like charges) with the induced voltage of one magnet only? 2.compare the induced voltage of attached magnet (opposite poles) with one with only one magnet Homework Equations The Attempt at a...

what happens when a permanent magnet is wound with a copper wire (inductor) and the inductor is connected to some volatge? Will the magnetic flux of the permanent magnet increase (i.e., make the permanent magnet more strong)?

Magnet attached to boat, would it work!? OK, if there was a boat with a magnet held in front of it by some sort of arch/crane attached to the boat would the boat be pulled towards the magnet, thus moving the boat forward, or would it just stay still. ______ o [________]...

Hi! I'm a new face here and have an easy question. I know how to calculate induced current when magnet moves through coil (it's E=BLv) but how do you calculate how much a magnet will decelerate when it goes through the coil? Will it decelarate at all? I have one of those mechanically-powered...

I think magnet has to be a conductor of electricity if is made of iron or steel. So, What happens when we pass a direct current through a magnet? What if we pass through AC? Does the passage of current effect the strength of the magnet?

I am working on a project that will use cylindrical neo magnets. Is there an ideal height to diameter ratio for neo magnets?

I have 1 week to build a motor. I'm looking at building a homopolar motor. I know I need a magnet. But does it have to be a neodymium one? And is Amazon a good place for such magnets? And does the screw have to be a ferromagnetic one? And if anyone has built such a motor, some hints and...

My question is: does a north pole attract or repel a piece of metal ? My attempted answer is: I think that the north pole alone would not attract a piece of metal. Instead it would require the north pole in conjunction with the south pole to attract a piece of metal. Can someone please confirm...

I have a bunch of rare Earth magnets that I bought a few years ago. For the most part, they've been rather haphazardly stored in a jumbled mess, with a few others stuck on the refrigerator. Today I noticed that at least some of them are noticeably weaker (particularly noticeable with the...

I came across a couple of cow magnets a while back. When you drop a cow magnet down the center of a vertical piece of steel conduit, it doesn't drop as fast as it usually would. When you drop a cow magnet down the center of a vertical copper plumbing pipe (closer fitting than the conduit)...

Hi PF, A disclaimer, I am no good at Physics or math. My question: When calculating the pull force between two magnets it seems to always be calculated at an angle perpendicular to the surface of the magnet. I was wondering what effect on the force required to "pull" one magnet away...

I have just learned electromagnetic induction and it states that if you move a magnet through a solenoid, you would get an induced current. Say, if you have a copper solenoid, and if you want to move a magnet through it, there will be something (maybe, a force) that would prevent the magnet...

This is sort of a thought experiment. I want to find out if my approach to this is correct. How can I analytically find the magnetic field from a permanent magnet? My approach would be to consider the magnet to be a lattice, with each lattice point being a molecule with a magnetic dipole...

My specific question is can the magnets in an Ashton BA15 40W bass amp damage the HDD in a laptop (we have a Samsung about a year and a quarter old and an Acer about a year old). I've read the following threads: https://www.physicsforums.com/showthread.php?t=411895&highlight=magnet...

Hi, I am proposing a simple way to create a magnet with single pole. Not being a physics/science graduate, this came out of interest of thinking only. Lets consider a sphere, which is hollow inside and has a thickness to it at the surface only. If i cut a certain segment and make it out of...

Homework Statement A length of wire extends upward through a piece of cardboard, bends around, forming a loop, and extends back down through the cardboard. All that is visible above the surface of the cardboard is this loop of wire. From your perspective, you are looking downward on the piece...

Say you have a magnet, one end of the magnet has a positive charge and the other end has a negative charge. What would happen to the magnet if you broke it in half?

My apologies for posting something that I'm sure people will say has been answered before, but a trawl through the results of a search of magnets didn't come up with a satisfactory answer. If I hold a permanent magnet a few centimeters over my desk and slowly move it across a paperclip the...

Hello everyone, curious about something here. I saw a demonstration lately were a magnet was dropped down a copper pipe and the magnet dropped very much slower than expected. What I got to thinking was, if you replaced the copper pipe with the same quantity of insulated copper wire in a...

When 2 magnets are on opposite sides of a table by moving one magnet the other moves also. could someone explain the physics/formulas or relations that correspond to this. Thanks

I'm trying to calculate the force between a solenoid and a magnet inside that solenoid. Would someone be able to explain how I would be able to calculate the force a solenoid of n number of turns and l length with a current I running through it would put on a magnet whose center is a distance d...

Homework Statement The Attempt at a Solution Suppose that N pole of magnet is facing the solenoid considering view from magnet when the magnet moves close ... current is anticlockwise and increase from 0 to max till magnet reach starting of solenoid when it enters the solenoid ...

Hi guys. I've got an interesting questions. I found it tricky maybe somebody knows the answer. When I attach to DC supply a capacitor with a coin 1 British Pound parallel to the capacitor and connected by two wires coming out of the capacitor, I always get kind of sparkles in my coin, the supply...

If you take a permanent magnet and wave it back and fourth, or even just move it along in one direction, this seems like it should create an electromagnetic wave. If so, how would one compute the frequency, and could you possibly detect it with a radio if you shielded it from other noise?

Problem Traditional electromagnets create a magnetic field when current passes through them. What I need is a magnet that loses its magnetic grip when current passes through. Is there a particular name for these kind of magnets / systems? Application I want the magnet to hold a metal...

A lift electromagnet has N + S pole on the same side. will it push or pull a permanent magnet which has N & S pole on opposite side? If I have a lift electromagnet and a permanent magnet, both can pull 100 lbs. What is the break away force if I put them together? Thanks

Greetings, I have been working on a permanent magnet alternator, axial flux configuration. It has been configured with vertically staked stators and rotors. The traditional fabrication technique the stator is one large diameter with a large diameter magnet rotor above and the below the stator...

I opened my harddisk and put a magnet on the plates but the plate acts like a piece of wood. I would expect the magnet to stick to the plate. It is a magnetic plate afterall! My "magnet" is in fact a row of neo cube balls which are quite strong magnets and small. So I would surely feel or see a...

Hello Forum, Does anyone know of any references on the construction of a Stern-Gerlach magnet? Most of the references I have seen so far discuss magnets that provide a constant field gradient (in the z-axis) over a few millimetres. Since I have a circular beam of about 1 cm diameter, I need a...

A beam of silver atoms (which are electrically neutral spin-1/2 particles) enters an inhomogeneous magnetic field, and is split in two. The state of an atom that has passed the magnet is often described as |U>|↓>+|L>|↑>, where |U> and |L> are states that are localized to the upper and...

Is it possible to levitate a magnet in a superconducting pipe or a ring? Is it possible to try to calculate this using the method of images and treat the magnet as a little current loop? Any input will be much appreciated.

Hi there I'm engineering a suspension system with the damper consisting of a magnet going through some coils. As the energy produced from this is proportional to the velocity of the magnet, this would be ideal for an "energetic" damper. To calculate the damping coefficient produced, I...

I am hoping someone here has experience with permanent magnets. I have a theory on how to size a permanent magnet for an alternator I am designing, and I want someone to confirm that my technique will yield a result that is useful enough to go through the expense of building a prototype. My...

So basically i have this powerful electromagnet that generates an electromagnetic field that can levitate another magnet and withhold a load of 12oz and still levitate: My problem is, I want to be able to use electronics and send wireless signals through this strong magnetic field. I can...

The problem I am having is that I cannot seem to find the magneto-motive force of a permanent magnet. Most material tables give a Hc in kA/m, which I take to mean I multiply by the length of the magnet, then by the area of the magnet to get my total magneto-motive force. So does...