This is a practical and theoretical question about magnetic fields.

Here is my phone case

enter image description here

That circle in the middle is advertised as:

Inside the center of the finger holder ring there is a piece of hidden iron that allows the case to be attached to the magnetic car holder.

Here is the magnet

enter image description here

This is advertised as a NdFeB magnet 30mm by 10mm disc with strength N52.

Expected behavior

I hope that placing the magnet next to the phone case on-axis will create the strongest attraction. And I am hoping that it will resist axial movement (remain on-axis but pull away) as well as lateral movement (remain touching disc-to-disc but moved off-axis).

Actual behavior

The strongest attraction is made when the phone case is touching the magnet face-to-face with a planar offset of one radius from the center.

Placing the magnet face-to-face with the phone case directly on-axis produces zero attraction or repulsion. It is unstable because it would really rather be 1r in any direction. It's like balancing a pea on top of a soccer ball.

A video demonstrating this is at: https://youtu.be/b5RiXP5SVkQ


Why does this magnet attract in this way? Would a different magnet give my desired behavior?

  • $\begingroup$ Have you tried the other side of the magnet... $\endgroup$ – AtmosphericPrisonEscape Apr 2 '19 at 3:05
  • 2
    $\begingroup$ Because it is April 1st? :) $\endgroup$ – cms Apr 2 '19 at 3:05
  • $\begingroup$ Does your magnetic car holder stick to the car as it should? Then the iron inside the phone circle is magnetized. If the magnet does not stick to the car, you should return it as having the wrong magnetization.The iron in the circle of your phone could have been magnetized if placed close to a strong magnet for a period. $\endgroup$ – anna v Apr 2 '19 at 5:40
  • $\begingroup$ I did not purchase the car holder; I'm just curious how the magnet is working. // Yes I tried both sides of the magnet, this is in the video, they act the same. // I just use this magnet to make the video, maybe this qualifies as strong enough to magnetize. $\endgroup$ – William Entriken Apr 2 '19 at 14:42

Could you have a diametrical magnet? enter image description here

Or radial?

enter image description here

Dura Magnetics, Inc.

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