# Naked Science Forum

## Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: hamdani yusuf on 16/06/2020 03:31:54

Title: How much iron is needed to stop opposing forces of magnetic poles?
Post by: hamdani yusuf on 16/06/2020 03:31:54
If we put two opposing magnetic poles facing each other, those magnets will be pushed apart by a magnetic force. But if an iron plate is inserted between them, the pushing magnetic force can be reduced or even reversed into a pulling force.
Is there a formula determining how thick the iron plate is required to neutralize the pushing magnetic force between the same magnetic poles?
Title: Re: How much iron is needed to stop opposing forces of magnetic poles?
Post by: evan_au on 16/06/2020 08:12:37
Quote
how thick the iron plate is required
If the iron plate is driven into magnetic saturation, it acts as if the iron plate is no longer there.
- The magnetic saturation level is strongly dependent on the exact iron alloy
- The field strength of the magnet will also affect the plate thickness

It is also probably affected by the field shape of the two magnets(?)
- I expect that two "horseshoe" magnets (2 poles close together) would need a thinner sheet than a pair of bar magnets (poles apart)

See: https://en.wikipedia.org/wiki/Saturation_(magnetic) (https://en.wikipedia.org/wiki/Saturation_(magnetic))
Title: Re: How much iron is needed to stop opposing forces of magnetic poles?
Post by: hamdani yusuf on 17/06/2020 03:57:45
- I expect that two "horseshoe" magnets (2 poles close together) would need a thinner sheet than a pair of bar magnets (poles apart)
What is the reason?
Title: Re: How much iron is needed to stop opposing forces of magnetic poles?
Post by: hamdani yusuf on 25/12/2020 09:09:53
I guess that it depends on the material's permeability.
https://en.wikipedia.org/wiki/Permeability_(electromagnetism)#Values_for_some_common_materials
It should also depends on the strength of magnetic field on the surface of the magnetic poles