It may be defined as the property of a substance due
to which it opposes (or restricts) the flow of electricity
to which it opposes (or restricts) the flow of electricity
(i.e., electrons) through it.
Metals (as a class), acids and salts solutions are good
Metals (as a class), acids and salts solutions are good
conductors of electricity. Amongst pure metals, silver,
copper and aluminium are very good conductors in the
copper and aluminium are very good conductors in the
given order.
* This, as discussed earlier, is due to the
presence of a large number of free or loosely-attached
electrons in their atoms. These vagrant electrons assume a directed motion on the application of an electric potential
electrons in their atoms. These vagrant electrons assume a directed motion on the application of an electric potential
difference.
These electrons while flowing pass through
the molecules or the atoms of the conductor, collide and
other atoms and electrons, thereby producing heat.
other atoms and electrons, thereby producing heat.
Those substances which offer relatively greater
difficulty or hindrance to the passage of these electrons are said to be relatively poor conductors of electricity like
difficulty or hindrance to the passage of these electrons are said to be relatively poor conductors of electricity like
bakelite, mica, glass, rubber, p.v.c. (polyvinyl chloride) and dry wood etc. Amongst good insulators
can be included fibrous substances such as paper and cotton when dry, mineral oils free from acids and water, ceramics like hard porcelain and asbestos and many other plastics besides p.v.c. It is helpful to remember that electric friction is similar to friction in Mechanics.
can be included fibrous substances such as paper and cotton when dry, mineral oils free from acids and water, ceramics like hard porcelain and asbestos and many other plastics besides p.v.c. It is helpful to remember that electric friction is similar to friction in Mechanics.
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