An electric wire is made up of metal coated with plastic
for insulation. Wire is an elongated, flexible metal filament
or thin rod that has a uniform cross section. Mostly aluminum
or copper is used in electrical wires. Steel, brass,
iron, gold, silver, and platinum are also used nowadays
for in wire industry.
Wire has many different applications in modern technology
and in household usage. Telephone wires are usually made
of copper, a good conductor. High-tension electrical transmission
lines are also made up of aluminum wire, which is again
a good conductor and is less expensive and lighter in weight
than copper wire.
Plastic used for electric insulation is made up
polythene is made from monomer ethylene (CH2=CH2)
Polythene is a thermoplastic; It is a soft plastic,
that softens on heating.
Why is metal used in wire as an electric conductor?
Electric current is the flow of electrons in a wire. In
metals, the outer electrons of the atoms belong to a 'cloud'
of delocalized electrons. They are no longer firmly
held by a specific atom, but instead they can move freely
through the lattice of positive metal ions. Normally they
Due to presence of free mobile valence electron,
when electric field is applied, this free electron moves
throughout the metal from positive to negative ends and
thus conduct electricity through the metal