Electromagnetism – How Can Any Material Provide Electrostatic and Magnetic Shielding?

electric-fieldselectromagnetismmagnetic fields

Several metallic objects like Iron, Copper etc can provide electrostatic shielding (one should remain inside the car during thunderstorm) and several superconductors like HTS (High Temperature Superconductors) provide magnetic shielding against the magnetic fields.

So how can such fields be repelled by these types of materials? I think it might be because of their atomic arrangement but I am still not sure that why only some of the elements from the periodic table (transition metals) provide these shielding. I mean every element in periodic table have some electrons, protons and neutrons. How these atomic arrangement influence them?

Also I want to know that why magnetic field is so specific in nature (it can be shielded only the zero resistance material). Is there any relation between the zero resistance material and it's magnetic shielding.

Best Answer

Your question is very broad and difficult to answer completely - I hope the following comments will be useful.

  • Electrostatic Shielding - this is provided by metals which have 'free electrons'. In the metal some of the electrons from the atom can move about throughout the metal. These electrons provide the electrostatic shielding and this is also why metals appear to be 'shiny' they reflect light well because of the free electrons.

  • Magnetic Shielding - Two cases

1) Superconductors - this is a special case because superconductors have no resistance they will prevent magnetic field lines passing through them - they make an electric current circulate inside them to exactly counteract and reduce to zero the magnetic field that approaches them.

2) Transition metals - ferromagnetic materials - Ferromagnetic materials have 'unpaired electrons'. These unpaired electrons generate magnetic fields, which can line up with or against magnetic fields. Special ferromagnetic materials can block magnetic fields - e.g. mu metal as mentioned in the Comment of Jon Custer above. Transition metals are unusual compared to other metals because they often have unpaired electrons. This is because of their position in the periodic table and the 'd' subshells.

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