RE-NEET2024Physics-Current Electricity
RE-NEET 2024 Physics Drift Velocity MCQ Question
Type: MCQ-conceptual-Medium-Class 12
A uniform wire of diameter d carries a current of 100 mA when the mean drift velocity of electrons in the wire is v. For a wire of diameter d/2 of the same material to carry a current of 200 mA, the mean drift velocity of electrons in the wire is
A
4v
B
8v
C
v
D
2v
Correct Answer
Option B
Detailed Explanation
The drift velocity v is proportional to the current I and inversely proportional to the cross-sectional area A (v ∝ I/A). Halving the diameter reduces A by a factor of 4, so to maintain the same current density, the drift velocity must increase by a factor of 8.
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