Magnet Definition and 912 Threads

A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nickel, cobalt, etc. and attracts or repels other magnets.
A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field. An everyday example is a refrigerator magnet used to hold notes on a refrigerator door. Materials that can be magnetized, which are also the ones that are strongly attracted to a magnet, are called ferromagnetic (or ferrimagnetic). These include the elements iron, nickel and cobalt and their alloys, some alloys of rare-earth metals, and some naturally occurring minerals such as lodestone. Although ferromagnetic (and ferrimagnetic) materials are the only ones attracted to a magnet strongly enough to be commonly considered magnetic, all other substances respond weakly to a magnetic field, by one of several other types of magnetism.
Ferromagnetic materials can be divided into magnetically "soft" materials like annealed iron, which can be magnetized but do not tend to stay magnetized, and magnetically "hard" materials, which do. Permanent magnets are made from "hard" ferromagnetic materials such as alnico and ferrite that are subjected to special processing in a strong magnetic field during manufacture to align their internal microcrystalline structure, making them very hard to demagnetize. To demagnetize a saturated magnet, a certain magnetic field must be applied, and this threshold depends on coercivity of the respective material. "Hard" materials have high coercivity, whereas "soft" materials have low coercivity. The overall strength of a magnet is measured by its magnetic moment or, alternatively, the total magnetic flux it produces. The local strength of magnetism in a material is measured by its magnetization.
An electromagnet is made from a coil of wire that acts as a magnet when an electric current passes through it but stops being a magnet when the current stops. Often, the coil is wrapped around a core of "soft" ferromagnetic material such as mild steel, which greatly enhances the magnetic field produced by the coil.

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  1. A

    I Metal Ball Rolling in a Parabolic Bowl in the presence of a magnet

    I found this equation as a solution to the original problem of a point-like ball rolling without friction in a parabolic cavity from Lagrangian mechanics: Is it possible to add an extra force to this equation? I want to add a "magnet" at a certain position that will affect the ball. The...
  2. Heisenberg7

    B Magnet inside a solenoid with current

    What would happen if we tried forcing a bar magnet into a magnetic field created by a solenoid (look at the picture)? Assume that both the bar magnet and the solenoid are isolated form any other source of a magnetic field. What I am thinking: First of all, if we tried forcing the north side in...
  3. B

    B How is the magnet being affected in this diamagnetic application?

    I am using an exremely stong magnet to deflect a diamagnetic substance( in this case water) Is the magnet being deflected against the dianagnetic Or is the defection only present in the diamagnetic substance?
  4. W

    B Why does a magnet attract metal objects?

    Hi, there! I am studying magnetism right now and I can’t understand how does a magnet work. I read that the magnet has a magnet field, which influences only charged particles with velocity. But then how does magnet attracts metal objects, e.g iron nail? I read that in metals there are free...
  5. kirito

    what the relation between the amplitude magnitude and mass at resonance?

    should I be expecting a higher amplitude at resonance for a mass that's heavier to an extent form another where each is attached to a spring vertically , I assumed that's true since the heavier mass will stretch the spring more meaning when moving like a sin or cos wave the amplitude...
  6. rubixx14

    I Effect of Fringe Fields for a Bending (Dipole) Magnet on Field Integral?

    I'm doing some modeling of a bending magnet in FEMM, to use as a magnetic spectrometer, and came across the following equation: with the setup of the magnetic spectrometer similar to the following figure: At first I modeled a hard edge scenario in a 2D cross section, where no fringe fields had...
  7. Mitchell Richardson

    Finding force between solenoid and magnet

    $$\mu = 4\pi \times 10^{-7}$$ $$n = \frac{180}{0.135} = 1333.33$$ $$I = 1.85$$ $$L = 22.619$$ $$r = 0.014$$ $$F= \frac{\mu \times 1333.33 \times 1.85^{2} \times 22.619}{2 \pi \times 0.014}$$
  8. R

    B Help with science experiment magnets/force/acceleration/speed

    Sorry, I guess I should have remembered all of this from my school days, but right now I have forgotten so much that I need some help. I am developing some simple experiments for school children (age ca. 12). This one involving magnets. I am not asking for detailed calculations, that is way...
  9. M

    Force between poles of two magnets

    The Biot-Savart law gives us the magnetic field created by an electric current. We can calculate the force exerted on a moving charge by this magnetic field using Lorentz's force formula. But my textbook doesn't address the repulsive or attractive force between like or unlike poles...
  10. LaraKnowles

    Do fluctuations in Earth's magnetic field cause heart attacks?

    https://biomedscis.com/fulltext/the-effects-of-solar-activity-and-geomagnetic-disturbance-on-human-health.ID.000203.php ''m) Solar activity may contribute to the development of and be a trigger of the exacerbation of nervous and mental disorders, such schizophrenia, Alzheimer's disease, and...
  11. FEAnalyst

    A Magnetization and magnet poles

    Hi, electromagnetism is definitely not my area of expertise. However, I sometimes get to deal a bit with simulations of electromagnetic problems. One thing that bothers me now and I can't find the answer to it is whether magnetization ##M## is different for north and south pole of a magnet...
  12. E

    B Magnetic attraction force Question

    Other than the most simple school stuff of attraction, repulsion and "lines of force", I've never studied magnets. Hence this question. On the left we have a disc magnet diameter D attracted to a much larger lump of steel with force F (when there is no gap between)...
  13. C

    I Prevent a robotic cleaner from climbing on a block of iron with a magnet?

    Hi, very trivial question, sorry, but I did not find the answer on the net. I have a robotic vacuum cleaner, https://i02.appmifile.com/248_operator_sg/07/03/2023/b083a6129f828ac367c4600b0a78b85b.jpg?f=webp and it's constantly bumping into and trying to climb on the massive iron one-pilar foot...
  14. april7

    I Measuring change of magnetic field strengh over distance

    I have few cylindrical neodymium magnets of same diameter and different heights and different magnetic inductions in the geometric center of the magnetic pole surface. Knowing those values of magnetic induction, how can I measure what the induction is at a certain distance from that center? For...
  15. Wo Wala Moiz

    B Can we use a permanent magnet and a copper rod to create an electret?

    Electrons have a magnetic dipole moment. If a permanent magnet was held against one end of a copper rod, the delocalised electrons close to the magnet would be attracted and concentrate around the magnetic pole. This should result in the creation of a weak electret because of the uneven...
  16. doomer

    I Geometry of Magnetic field lines as they approach a magnet pole?

    Magnetic field lines are loops, so at the surface of a magnet (axially magnetized) cylinder) pole they look like this? there is a dead zone at the center where there is no lines/magnetic field present? or perhaps they look more like this? lines converge in the middle to a single line or point...
  17. M

    What are some fun permanent magnet experiments for kids?

    Howdy. My kids and I like to experiment with things, we're looking to play around with some permanent magnet experiments and when I googled a question it brought me here, so I figured, heck, might be able to get my questions answered as well :)
  18. M

    B Basic Straight Line Permanent Magnet Accelerator

    I stumbled upon this video on YouTube: Here is a screenshot with some colored lines added of the part that generated a few questions in my head that I hope some of you smart folk can answer for me. In the video, the spherical magnet (at the end near the two big magnets) appears to increase...
  19. S

    I Can Conducting Current Through a Bar Magnet Cause Movement?

    Following the Picture below, If I Conduct current through Permanent magnet Bar and hold the battery still. Will the magnet move in any direction ? Thank you.
  20. H

    I The Mystery of Magnet Rotations: An Unanswered Question

    This happened a long time ago, and I haven't found the answer. I posted a post on the Internet, and no one gave an explanation, so I really hope to find the answer. A magnet, no matter which pole is facing up, will rotate counterclockwise, as shown in the figure below. The magnet will not spin...
  21. T

    B What is the principle of a magnet?

    I cannot explain that if I divide a magnet with a north and a south pole into 2 parts, the force in it rearranges itself into 2 poles. Where is the center of power? How can I explain the principle of magnetic force if I don't take it as a matter of fact.
  22. M

    Flux from magnet (Why is the Flux not zero through the loop?)

    For the problem attached, Why is the magnetic Flux not zero through the loop? Many thanks!
  23. MatinSAR

    Period of a simple pendulum with a magnet under it

    Hi ... I have answered this question and I think that F/mg equals 3. But I've asked it from someone and he told me that F/mg is 4. Can someone help me find out which one is correct ??? My answer :
  24. D

    B Voltage gradient distortion in Copper when part is over a magnet

    I am working with HS students on measuring Current Gradients in Copper for their science project " Current Gradients in the human body during surgical cauterization". Next year I was thing of putting a thin sheet of Copper over strong magnets and using the Voltage gradient to draw the Current...
  25. alukhm

    Wood/Glass/Metal Magnet Inside a Shell containing Ferromagnetic Metal

    Hello all! I have a earring project with magnets involved but no magnet expert involved :( Here are a few stupid questions I hope someone can help us with! BACKGROUND: We are designing magnetic earrings. The earrings are meant to clamp the ear with 3 different levels of pressure. The magnetic...
  26. Lotto

    How to calculate magnetic induction just beyond the end of the magnet?

    I know I should use a limit $$B=\lim_{r\to l}{\frac{\mu}{4\pi}\cdot \frac{4rml}{{\left({r}^2-l^2\right)}^2}},$$,but in Wolfram I get a weird solution. https://www.wolframalpha.com/input?i2d=true&i=Limit[Divide[4rl,Power[\(40)Power[r,2]-Power[l,2]\(41),2]],r->l] What is the solution? It...
  27. vdance

    How are the poles of a tapered magnet distributed?

    How are the poles of a tapered magnet distributed? Is there any way to calculate its magnetic force?
  28. sergiokapone

    I How does a rotating magnet create levitation?

    Is any physical explanation of this effect?
  29. J

    I Air friction in rotating ring magnet

    As can be seen below we have 3 ring magnets. The middel one floats in between the other two. We want to know how to calculate the air friction of the middle ring magnet if this rotates.
  30. M

    Calculating the force that a permanent magnet exerts on a particle

    Dear readers, I have a question regarding permanent magnets and the force they generate on particles, which is far from my comfort zone. I have the option on using two types of permanent magnets and with two different setups. Imagine that we want to attract small particles using the magnets...
  31. N

    I Exploring Magnetic Force: Magnet vs. Wires

    I understand the iron fillings become little magnets all pointing in the same north south direction similar to the spin aligned electrons in the permanent magnet. Similarly, a compass near a wire traces out the magnetic field lines ie North/South. My question is how do I reconcile the fact that...
  32. SBrownJC

    EE: How to heat a magnet with a wire while levitating a superconductor?

    Hi I'm doing my extended essay (like a research paper) for the IB and I'm having a bit of trouble with my setup and data process. The plan for my experiment goes something like this: I have a magnet wrapped in wire strapped to a battery and a superconductor in liquid nitrogen. After levitating...
  33. X

    I Magnetic field strength of a stack of magnets

    I know that for a single cylindrical neodymium magnet, the formula $$ \displaystyle{\displaylines{B(z)=\frac{μ_0M}{2}(\frac{z}{\sqrt{z^{2}+R^{2}}}-\frac{z-L}{\sqrt{(z-L)^{2}-R^{2}}})}} $$ shows the relationship between the magnetic field strength and the distance between the magnet. I was...
  34. kuruman

    Insights How to Model a Magnet Falling Through a Conducting Pipe

    Continue reading...
  35. kuruman

    Insights How to Model a Magnet Falling Through a Solenoid

    [url="https://www.physicsforums.com/insights/how-to-model-a-magnet-falling-through-a-solenoid/"]Continue reading...
  36. S

    B Can you turn a skyscraper into a magnet?

    Curious to know if possible to create an electromagnetic field around a skyscraper if you run sufficient current through the structural members (ie interconnected column and beam network). Thanks in advance to any takers...
  37. billyt_

    Drop height of a magnet vs. induced EMF in a solenoid

    I am currently working on an experiment that involves dropping a magnet from varying heights and measuring how the induced emf of a solenoid changes as a result. I am currently somewhat struggling with a derivation for a relationship between the two variables, however, this is what I have been...
  38. egoodchild

    I Calculating distance (from magnet) to an arbitrary point in 3D space

    So I'm looking for some advice on a problem that I am trying to solve for a project. I'm an engineer but my background in vector mathematics is very minimal so I'm looking for some assistance. Lets assume we have a permanent magnet. We know the characteristics of this magnet, such as it's...
  39. S

    I Magnet through Pipe Experiment, continued

    The changing magnetic field of a falling magnet induces currents in the pipe that slows it's fall through the pipe. Question: If the induced currents are decreasing the magnets descent then they must themselves have momentum. How is it dissipated once the magnet has passed through the end of...
  40. rayjbryant

    I Quantifying the magnetic force on a magnet moving through a coil?

    So I'm familiar with the magnet falling through a copper tube demonstration that shows the induced magnetic fields slowing the magnet down. I know that this experiment is also possible with a conducting coil as long as the coil forms a closed circuit. I'm trying to find a way to calculate the...
  41. hagopbul

    Mysterious Reaction to Small Magnet: Investigating an Unexplained Phenomenon

    Hello All : Good day : i found a small magnet and it reacted strangely with my body , the magnet is 5 mm in diameter , and less than 4 mm thickness , i rob it few times on my left hand vain it stuck , which i do not understand why ! i checked on other people about 3 one of them had the same...
  42. G

    B A moving magnet in a linear electric field

    If a electrically charged mass travels thru a magnetic(m) field, it will accelerate at right angles to its velocity and the m-field. Under some conditions like this the charged mass will travel in a circular loop due to this magnetic force acceleration. This info is all over the internet. e.g...
  43. Woomir

    I Why is my magnetic levitation experiment not working?

    [Mentor Note -- Two similar thread starts merged into one] Hey all, I have been working on this project for a while now, which features suspending an object midair through the use of magnetic levitation principles. Cool right? And so I have been researching and trying, even finding ground...
  44. S

    Maximum detectable distance between magnet and magnetometer

    Hi Dear, I have a single-component (Z-Axis) magnetometer with 60nT resolution. I want to calculate the maximum distance that this magnetometer can detect an N52 magnet with a volume of 1 cm³. So I used the following formula and inserted the values, and finally calculated the Z...
  45. O

    I Magnet falling though copper pipe

    I do not fully understand why a falling neodymium magnet is decelerated in a vertical copper pipe. It is usually explained by Lenz's law, two induced currents generate an upward force that counteracts the force of gravity. (link) However, I assume this upward force has to be generated by the...
  46. R

    Generator winding using diametrically opposed magnet.

    I’d like to build a high speed generator using a diametrically opposed magnet. I’m asking if when using a diametrically opposed magnet rotating on a shaft if the generator coils can simply be a continuous wound loop around the magnet like a electro magnet is wound therefore only requiring one...
  47. G

    A Explain how a magnet can store up 200 times more energy for 24 hrs.

    I have a magnet that will lift only 1 lb of steel with an electric lift. If I discharge a big capacitor into a 1000 turn coil with the magnet in the center of the coil it super charges the magnet it will lift 200 lbs for about 4 seconds. The magnet has a half life of about 4 second for about...
  48. ChBhHu

    Electronics Remote Control Magnet Force: Possible?

    is it possible to create a remote that can control the force acting on a magnet? for example is, to stop one magnet from attracting or repulsing other metals. or making a magnet adjust the force it apply to other object.
  49. Y_G

    Optimetrics simulation of a coil and moving permanent magnet in Ansys Maxwell

    I'm trying to simulate a Magnetostatic problem. In my model there are two coils and a reciprocating permanent magnet. I defined a parameter, Xpm (movement of permanent magnet) in x direction to imply the reciprocating movement of permanent magnet like a piston. Xpm = f(t). I defined "t" as sweep...
  50. W

    I Does a Magnet Curve Spacetime More Than a Non-Magnetic Mass?

    Hi. My question is described in the summary. I'm seeking some advice. The Reissner-Nordstrom solution for charged spherical bodies seems to indicate that electrostatic fields will be a source of gravitation. I've not seen anything similar for magnetic fields but I can't imagine how it could be...
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