(i) Define the term drift velocity . (ii) On the basis of electron drift , derive an expression for resistivity of a conductor in terms of number density of free electrons and relaxation time. On what factors does resistivity of a coductor depend ? (iii) Why alloys like constantan and manganin are used for making standard restores ?

(i) Define the term drift velocity . (ii) On the basis of electron dri

1.	(i) Define the term drift velocity . (ii) On the basis of electron drift , derive an expression for resistivity of a conductor in terms of number density of free electrons and relaxation time. On what factors does resistivity of a coductor depend ? (iii) Why alloys like constantan and manganin are used for making standard restores ?
Answer» (i) Drift velocity is defined as the average velocity with which the free electron gets drifted f in the direction of external electric field applied. (ii) See Q. 27 2012 Set-I O.D., [Page 153] (iii) Low value of temperature coefficient and high specific resistance .

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