ماده غير نافذة للمجال المغناطيسى ..ماهى؟

[عبدالعال نوفل]

ارجو مساعدتى .. اريد معرفة المواد التى تقوم بعدم نفاذ المجال المغناطيسى ولكم خالص شكرى وعظيم امتنانى

[عبدالعال نوفل]

عندما طرحت هذا السؤال كنت اعتقد ان هناك مواد تمنع مرور المجال المغناطيسى وانتظرت اى ردود من اعضاء المنتدى ولكن لم يصانى رد واحد واثناء بحثى للأجابة على هذا السؤال وجدت هذه الاجابة عسى ان يستفيد منها الآخرون
How can a magnetic field be stopped?
Is there anything through which a magnetic field cannot pass?

A magnetic field cannot be completely stopped, but it can be reduced.

An alternating magnetic field, like that produced by a radio transmitter or resulting from the alternating electric current (AC) in a transmission line or transformer, can be reduced by shielding.

If enclosed within an electrically conductive container, such as a box or sleeve, magnetic fields will induce currents in the container. With careful design, these can be made to cancel the magnetic field. Such containers are typically made of copper or aluminum.

Containers made with most types of magnetic steel will reduce static fields (from a permanent magnet) and time changing (alternating) fields because the field prefers traveling through the steel walls rather that through the air.

Magnetic permeability is a measure of the amount of magnetism a material will acquire in an applied magnetic field. For specialist applications, such as around oscilloscope tubes, magnetic shields are built using materials with very high magnetic permeability. One such material is µmetal (mu-metal), which has a magnetic permeability much higher than steel, copper or aluminum. Deformation (e.g. bending) of µmetal can dramatically lower its magnetic permeability. Heating (annealing) at temperatures above 400ºC can recover its special magnetic properties.

For more information about µmetal and magnetic permeability try Wikepedia