Analyzing the Force of Two Disk Magnets on a Metal Plate

AI Thread Summary
Two disk magnets are positioned with their north poles facing each other, creating a repulsive force while a metal plate is fixed to rotate between them. The magnetic fields do not connect directly; instead, they bend outwards, resulting in a plane of symmetry where the magnetic field strength is effectively zero. When the metal plate is placed between the magnets, the magnetic field lines pass through the metal, but the forces from the magnets do not cancel out, as there is no field in that central area. The pull on the metal plate is less than the force needed to rotate it out of position, confirming that the magnets' repulsion is dominant. Understanding this interaction clarifies the dynamics of magnetic forces in this setup.
Kupa140
Messages
2
Reaction score
2
The situation is as follows. We have two disk magnets. One is fixed on the ground, table, or surface and has the north pole facing up. Then we have a metal plate fixed on the vertical axis rod or something similar such that it can't move up or down, but only rotate horizontally with as less friction as possible. The metal piece is slightly above the surface of the first magnet and the magnet will obviously attract it.

We also have right above the first magnet and the needed space for the metal piece a fixed cylindrical tube holding the second identical magnet inside it, and it also allows the second magnet to slide up and down within the tube. The magnets are facing each other with the same poles, so north north. With nothing between the magnets, the second one would float above the first magnet with a given distance calculated by their repulsive force and so on.

Now to the question, the metal piece now rotates such that it's between the two magnets and the magnetic filed lines will now pass through the metal instead of air, the second one will fall lower than it's previous position and both will be attracted to the metal, would their force on the metal cancel each other out? If not, is their pull on the metal greater or lower than the necessary force needed to rotate the metal piece out of the position between them? My assumption is that a great deal is perpendicular on the metal and since the metal piece is fixed it should be less.
 
Last edited by a moderator:
Engineering news on Phys.org
Welcome to PF.

Kupa140 said:
The magnets are facing each other with the same poles, so north north.
There will be a plane of symmetry between the two north poles where there is no field. The two magnetic fields do not connect and flow through the two magnets, they bend out sideways and so avoid each other.

Kupa140 said:
Now to the question, the metal piece now rotates such that it's between the two magnets and the magnetic filed lines will now pass through the metal instead of air, ...
There is no field halfway between the magnets where you place the metal plate.
 
Baluncore said:
Welcome to PF.There will be a plane of symmetry between the two north poles where there is no field. The two magnetic fields do not connect and flow through the two magnets, they bend out sideways and so avoid each other.There is no field halfway between the magnets where you place the metal plate.
It took me a while but now i understand, thank you.
 
  • Like
Likes hutchphd and berkeman
While I was rolling out a shielded cable, a though came to my mind - what happens to the current flow in the cable if there came a short between the wire and the shield in both ends of the cable? For simplicity, lets assume a 1-wire copper wire wrapped in an aluminum shield. The wire and the shield has the same cross section area. There are insulating material between them, and in both ends there is a short between them. My first thought, the total resistance of the cable would be reduced...
Hi all I have some confusion about piezoelectrical sensors combination. If i have three acoustic piezoelectrical sensors (with same receive sensitivity in dB ref V/1uPa) placed at specific distance, these sensors receive acoustic signal from a sound source placed at far field distance (Plane Wave) and from broadside. I receive output of these sensors through individual preamplifiers, add them through hardware like summer circuit adder or in software after digitization and in this way got an...
I am not an electrical engineering student, but a lowly apprentice electrician. I learn both on the job and also take classes for my apprenticeship. I recently wired my first transformer and I understand that the neutral and ground are bonded together in the transformer or in the service. What I don't understand is, if the neutral is a current carrying conductor, which is then bonded to the ground conductor, why does current only flow back to its source and not on the ground path...
Back
Top