InterviewSolution
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InterviewSolution
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Using the concept of drift velocity of charge carriers in a conductor, deduce the relationship between current density and resistivity of the conductor. |
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Answer» Solution : DRIFT velocity of charge carriers is the CONSTANT velocity ACQUIRED by them in a conductor on applyingan external electric field E on it. The CURRENT density J through a conductor depends on the drift velocity as per relation : J= ne `v_d` , where n = number density of charge carriers (electrons). But `v_d = (eE)/(m) tau `, where `tau` is the relaxation time. ` therefore J= "ne" [(eE)/(m) tau] = ("ne"^2)/(m) tau E` However , `(m)/("ne"^2 tau) = rho`the resistivity of the material of conductor. Thus, we conclude that `J = E/rho " or" rho = E/J` It means that resistivity of a conductor is given by the RATIO of electric field applied .E. and the current density .J.. |
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