As per Matthiessen's rule, the total resistivity r of a conductor can be written

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Question
As per Matthiessen's rule, the total resistivity r of a conductor can be written as r = r_i + aT, where r_i and a are constants and T is absolute temperature. At very low temperatures
Options
A. aT = 0
B. aT > r_i
C. aT ? r_i
D. aT < r_i

Correct Answer

aT < r_i

Explanation

At very low temperatures a T ? 0. Since resistivity has a finite value even at low temperature, a T < r_i.