Attraction between a wall and a magnet

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SUMMARY

The attraction between a magnet and a wall is influenced by the wall's thickness, particularly when the wall is made of ferromagnetic material. For thin walls, the attraction decreases due to limited field lines being able to follow the wall, while for thicker walls, the attraction becomes nearly independent of thickness once it exceeds the diameter of the magnet's face. The governing equations involve magnetic field strength and the interaction between the magnet's field and the wall's material properties. For refrigerator magnets, the thickness has minimal impact on attraction strength.

PREREQUISITES
  • Understanding of magnetic field theory
  • Knowledge of ferromagnetic materials
  • Familiarity with magnetism equations
  • Basic principles of magnet-wall interactions
NEXT STEPS
  • Research magnetic field strength calculations for different materials
  • Explore the properties of ferromagnetic materials in depth
  • Study the equations governing magnetism and attraction forces
  • Investigate the behavior of magnets on various wall thicknesses
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Physicists, engineers, and anyone interested in magnetism and material science, particularly those studying magnet-wall interactions and their practical applications.

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Hi All,

I was wondering: for a given size and strength magnet sticking to a wall of a given material and surface area, does the thickness of the wall affect the strength of the attraction? What are the governing equations at play?

I am trying to gain insight as to why or why not the thickness of the wall would matter. Any light shed on the situation would be appreciated.
 
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Assuming that the wall is ferromagnetic: The field lines from the magnet will "try" to follow the wall outwards. However, the field strength in the wall is limited - if it is too thin, only parts of the field can follow the wall. This should reduce the attraction for thin walls. For thick walls, I think the attraction is nearly independent of the thickness.
 
For a bar magnet and an iron wall of finite thickness, the front wall attracts and the back wall repels. The force is zero for zero thickness, and gets larger as the thickness increases. Eventually, it will no longer depend on the thickness. This will start to happen when the thickness is larger than the diameter of the magnets face.
For a 'refrigerator magnet', there is very little dependence on the thickness of the wall.
 

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