In a wire of cross-section radius r, free electrons travel with drift velocity v when a current I flows through the wire. What is the current in another wire of half the radius and of the same materia

Question

In a wire of cross-section radius r, free electrons travel with drift velocity v when a current I flows through the wire. What is the current in another wire of half the radius and of the same material when the drift velocity is 2v ?

TestHub · Accepted Answer

I = n e v d ​ π r 2 I 1 ​ I 2 ​ ​ = v d 1 ​ v d 2 ​ ​ ( r 1 ​ r 2 ​ ​ ) 2 I 1 ​ I 2 ​ ​ = 2 ( 2 1 ​ ) 2 = 2 1 ​ I 2 ​ = 2 I ​ (C) ​

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JEE Main 2027 (Class 12+)