Question
Any current flowing through a copper wire when passed through an iron wire of same thickness. What will be the effect on its drift velocity?
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Answer
$I =n_e A_{v d}$ or $v_d=\frac{ I }{n e A}$, where $I , e$ and A are constant. Hence, $v_d \propto \frac{1}{n}$. The free electron density ( $n$ ) is less in iron than in copper, drift velocity will be more in iron than in copper.
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