Thursday, April 26, 2018

FACTORS AFFECTING THE RESISTIVITY OF ELECTRICAL MATERIALS

FACTORS AFFECTING THE RESISTIVITY OF ELECTRICAL MATERIALS 


1.  Temperature  :  The  electrical  resistance  of  most  metals  increases  with  increase  of
temperature  while  those  of  semiconductors  and  electrolytes  decreases  with  increase  of
temperature.  Many  metals  have  vanishing  resistivity  at  absolute  zero  of  temperature
which is known as superconductivity.


2.  Alloying : A solid solution has a less regular structure than a pure metal. Consequently,
the electrical conductivity of a solid solution alloy drops off rapidly with increased alloy
content.  The  addition  of  small  amount  of  impurities  leads  to  considerable  increase  in
resistivity.


3.  Cold Work : Mechanical distortion of the crystal structure decrease the conductivity of a
metal because the localized strains interfere with electron movement.
4.  Age Hardening : It increases the resistivity of an alloy. 

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