Magnet Definition and 912 Threads

Hello all, I'm a mechanical engineer who recently recently became interested in linear motors and generators (random, i know). I've narrowed my interest to tubular linear permanent magnet motors (servo types) such as the ones made by these people...

Hello, Newbie here. Guess this is going to be a pretty odd first post. I've recently been having a discussion with a few friends, regarding whether it's plausible that magnetic bracelets could have any form of healing potential (for arthritis and similar conditions). To me, my friends lack of...

Suppose I'm holding a magnet and then lift a paperclip(or another magnet) with the magnet. Now the energy density of a magnetic field or the energy that went into making the magnetic field is W = \frac{1} {2 \mu_o} \int B^2 d \tau but since work was done in lifting the magnets, what happenes to...

First, this is not a post about perpetual motion machines, although thinking about perpetual motion machines made me think of some issues. Something that is bothering me is the idea of a magnetic force not doing work. Well sort of. It’s completely clear to me that the magnetic field does no work...

Hi, I am trying to work out if a small magnet can be used to hold a thin sample that I have. The sample is flat and about 10mm x 10mm in size. The sample is a layer of copper, with nickel plated on that. There is then a gold coating on the nickel. The copper is 0.05mm thick, the nickel 0.005mm...

this video ( ) demonstrates lenz's law, if the current produced by the magnet fall induces an opposing magnetic field , after many tries , can this field demagnetize the magnet , another thing, consider this : if the copper pipe was instead a pvc pipe, and i wrapped around it copper wires , so...

Hey guys. I'm building a mini electric generator and I would like some clarification on Faraday's Law. So his law states that: V=-N*(ΔBA)/(Δt) Where voltage generated equals the number of turns times the negative rate of magnetic flux. So my question regards the number of turns part...

Hello Friends I am working on home made electromagnet and I have only volt & Ohms details like 12Volt DC, 24Volt DC & 240V AC and ohms is 80Ω, 100Ω & 120Ω for all for example 12VDC 80 ohms coil, 12VDC 100ohms,24VDC 80Ohms coil...etc. now i want to know which copper gauge we have to choose...

What happens If we give elecric to a magnet ?

I just found out today that this is a real thing, people can get a tiny neodymium magnet implanted into your finger tip and apparently it allows you to feel the electromagnetic field, and the strength varies depending on where you are and what your hands are close to. I just wondered what...

Gentlemen, the the image shows 2 N48 neodymium magnets of the same volume 54 in2. On several website I can use magnetic flux density calculators to get the Br of the rectangular magnetic but haven't found one that calculates the value of the arc magnet. The Br value of the rectangular magnet is...

Hi my name is HopelesslyFaithful (HF) (forum didn't allow all chars). I am from Notebookreview and while googling for my project. I came across this site a thread that was helpful but also made more questions. I posted this on NBR so i did a direct copy paste hoping i could get some expert help...

Hello Physics Forums World this is my first post so please be gentle. I am working on a project and wanted to understand the strength of magnets over distance. Imagine, if you will, two magnets both with a gauss of 3600, the opposite poles are facing each other. how would I calculate...

A magnet only attract ferromagnetic material because they have magnetic domains which will align to form magnetic dipole when external magnetic field applied. Paramagnet don't have domains. Due to the presence of some unpaired electron, they will cause the realignment of the electron path when...

Hi, I am trying to create a hall effect based position sensor to be attached onto a DC motor to generate feedback for position control. I am thinking of the following arrangement: 4 hall sensors are placed 90 degrees apart around the magnetic element. Each sensor surface is directed at the...

Homework Statement When putting a magnet into a solenoid, under what conditions is a current generated? The Attempt at a Solution In order for a current to be generated, the magnet needed to be moving as it passed through the solenoid. This is due to Faraday’s law, which states that an...

We just started magneto statics in school and were told about the use of magnetic monopoles for problem-solving reasons. So we were told that the magnetic length of a bar magnet differs from its geometrical length. I can't quite seem to figure out why we can't assume the monopoles to be right at...

OK... so my understanding is that a DC generator under no load generates high voltages without any current, but does the same hold true for an AC alternator? What happens with current when the RPMs of the alternator exceed what is necessary for the current requirements?

What is "magnet wire"? I have a test procedure I am trying to follow and it calls for "two strands of twisted magnet wire." I know it is referring to something like this: http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXHZW4&P=FR I know the transmission line characteristics of twisted...

Bar magnet... why are the magnetic poles of a magnet are located somewhere within the magnet,not at the ends?

Magnet Phenomenon: The "divergent" region of a ring magnet Here's a puzzler: I have a NdFeB ring magnet, 1.75" outer diameter x 1.375" inner diameter x 0.25" thick, N40 grade. It is axially magnetized so that the north pole is toward one face and the south pole is toward the opposite face. The...

Hey guys. I was just wondering about Mu-Metal. I'm sure you guys know what a Magnet "Keeper" is. If I was to take a thick piece of Mu-Metal and lay it across a magnet from the North to the South pole, would this act as a Keeper? I'm trying to reduce the amount of flux loss over time...

Hello all, I am a newbie here but have a question that I was hoping someone could answer. Would a permanent magnet give off a single frequency or would it give off a spectrum of frequencies, like an incadescent light bulb can give off a spectrum of frequencies? I can measure the intensity...

Permanent magnet can degenerate by many ways. But it really needed in compact generator to convert mechanical force into electric But are there any other way to generate electric from mechanical force without magnet? I want to design self exited magnet for dynamo. It need tobe an effect that...

I have a bit of a theoretical question. If one has a current carrying wire in a magnetic field such as in an electric motor rotor, does the resulting force on the wire also impart an opposing force on the stator magnets which are producing the magnetic field as Newton’s third law says? Also, if...

A mechanical design question, just wanted to pick your brains about a project I'm working on. I have a fixture that houses a magnet, when an operator loads a part with a screw the magnet jumps and a thru beam on the magnet detects that a screw is present. Without a screw (below) the magnet...

I'm trashing the template here because I'm not looking for help with how to solve my homework problem. Instead, I'm looking for what my question actually means! I'm given an equation that describes a magnetic field. One of the specs I'm given is that the magnet period is 10cm. What in the...

Let's say you have a strong spherical neodymium magnet (for the purposes of this example, let's give it a 1 cm diameter), and you were to place it on a machine which rapidly rotates the magnet. If you were to rotate it at 100 MHz, could you build an FM radio transmitter? Supposing it were...

If you were to levitate a superconductor using a permanent magnet due to the effects of the Messiner Effect, and you were then to lift the permanent magnet with your own hands, would you be lifting the mass of the permanent magnet, the mass of the permanent magnet + the mass of the...

Magnet dropped down a copper tube experiment (magnetic braking?) Homework Statement Experiment: what is the effect of the # of magnets on the time of drop through the pipe? Magnets are placed in a paper cylinder container - "one magnet" is 1 magnet and 5 weights (mass of 1 magnet and 1...

Im looking to do some projects with permanent magnets. I don't have access to a gaussmeter and I'm wondering if there are any sites that have representations, descriptions or formulas for the field strengths of ferrite or neodymium magnets. Also i need to learn about how magnetic fields...

Hi, Recently I came across an annular permanent magnet (round magnet with a hole in it) which had fallen and broken in half, effectively forming two horse-shoe magnets. I noticed that the two halves had similar poles: |---------- S S-------- | | |...

Homework Statement Homework Equations The Attempt at a Solution What is the expression for the magnetic field of a magnet? Biot Soviet law cannot be used since there is no current. What should I do? I get stuck at the final step shown below.

I am working with an application where we have a magnet in close proximity to an antenna in the 20 - 25 GHz range. If there IS and affect of the magnet to the antenna's transmission, does the "near field" calculation apply (λ/2xpi)? If the antenna is out of the near field, is there no affect...

Magnetism of a bar magnet -- maximum rate of change? If a bar magnet is placed along the x-axis with (0,0) at its center, along which axis does the magnetic field fall off faster and why?

Hi I want to pass DC current through a magnet, essentially using it as connector. The magnet I am using specifically is Neodymium (NdFeB) grade N42. The DC current I would like to pass through it is 100mA ~ 150mA (3V DC ~ 7V DC) I would like to know if there is any downside to the magnetic...

Hey guys.. I trying to build an magnet which can pull an object with 5N.. I am using S37 as my the iron for my horseshoe magnet, And been using this formula to convert Newtonian Force to magnetic force \vec{F}=\frac{B}{µ0}*A A= cross sectional area = 0,002*1/100 M^2 B = Magnetic Force...

Homework Statement A sphere magnet of radius a has permanent uniform magnetization, z-axis. So we were trying to find the magnetic field at the center of the magnet in class. Homework Equations j_M(θ)=Msin(θ) dI=j_M(θ)adθ circular loop r_{loop}=asin(θ)The Attempt at a Solution When using...

Is there a way to calculate the magnetic field strength, B, of a magnet (permanent magnet, not an electromagnet) at a certain distance? I assume it follows the inverse square law, but other than that, I do not know what to do. Tools I have available: permanent magnet ammeter/voltmeter...

In physics lab we positively charged a metal sphere then placed a compass near it and both ends of the compass were attracted to the sphere. I know magnetic fields are created by electrons, so I made the assumption the compass is attracted to the positive charge because the electrons in the...

The Idea The idea is similar to a pendulum in motion. I noticed that it was possible to shift the weight towards a single direction causing an immediate force, which equalized over time. I figured I could use magnets to simulate a pendulum and also reset to the starting state using both...

New here, hello all. My question is more about the field magnet in a running DC motor. First of all, does the current required to maintain a magnetic field change with the load on the motor? And if so, where would this "extra energy" come from in a permanent magnet DC motor?

I am reading a paper where the bending power of a dipole magnet is described as 2 Tm. Is that Tesla*meter? Is bending power actually power i.e. Work/Time? Can someone explain this physical quantity to me, please?

Homework Statement Today, my teacher gave us some practice AP multiple choice and my friend and I were debating between answer choices H and J (changed from A and B to remove any confusion) the question as i remember it: blah blah... B-field into the page, constant velocity v, radius R and...

When a magnet has a value of.. let's say 10 Tesla, what does this mean exactly? Does this mean the magnetic field value directly on the poles has a value of 10 Tesla?

I'm an inventor and I have an idea involving magnets. Unfortunately, I'm having a hard time trying to interpret magnetic equations. Please forgive me if I sound like a noob.. I'm new to magnetism. Lets say you have a bar magnet with a field B, oriented perpendicular to a wooden interface...

I was wondering what voltage or current, if any, would be produced if the basic magnet through a copper coil experiment had the poles rotated 90 degress so north and south faced the top/bottom of the coil rather than the entry/exit points? The attached image has a basic illustration of this...

After watching a fascinating youtube video demonstrating the Lenz Effect using a 1.5T MRI machine and an aluminum block, I was wondering if it would stop a bullet fired along the axis of the machine. If so, would there be any defensive military application?

Hello all, This is just a question i have... I need to know the frequency (in order to meter it) from an electromagnetic source, and i know that a neodymium magnet will disrupts it. so, i want to know what range the neodymium will disrupt, in order to know what device will need to meter...

I've been wondering how does this motor work (if it is not hoax in the first place) I was thinking about Ampere's force but apparently it doesn't really have an affect here. Any ideas?