Magnetic and Electric Properties

Name: Ravi
Status: other
Grade: other
Location: IL

Question: 1. Can we correlate magnetic properties of
materials with electrical properties? i.e. If the material is insulator,
will it have specific magnetic properties(paramagnetic or diamagnetic or
ferromagnetic). 2. Is it possible for a conductor the
surface layer can be insulating(not because of chemical reactions takes place
on the surface) and the other layers can be conducting? If so how
can we identify a material as a conductor or insulator? 
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Hi Ravi,

To answer your first question, there is no specific
correlation between magnetic and electrical properties of
materials. Permanent magnets, for example can be electrically
conducting (such as those made of ALNICO, or steel), or they
can be electrical insulators (such as ceramic magnets used on
most speakers, refrigerator magnets and so on). Both these (one, an
insulator and the other a conductor) exhibit the same
ferromagnetic properties.

Answering your second question, I am unaware of any
contiguous material that has conductance throughout its bulk,
but is an insulator on its surface. Of course this can be
achieved chemically, for example when the surface of aluminum
is oxidized by the process known as anodization. Similarly,
one could imagine a lump of graphite (a conductor) whose
surface was somehow converted to a thin layer of diamond (an
insulator), even though these are both just allotropes of
plain carbon. But I believe this sort of thing is not what
you were referring to. If a material is contiguous
throughout, it is hard to imagine how the atoms or molecules
of that material would "know" they were close to the surface,
and therefore should change somehow from a conductor to an
insulator.

Regards,

Bob Wilson.
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