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Question: Answered & Verified by Expert
A current of 5 A is passing through a metallic wire of cross-sectional area $4 \times 10^{-6} \mathrm{~m}^2$. If the density of charge carriers of the wire is $5 \times 10^{26} \mathrm{~m}^{-3}$, then the drift velocity of the electrons will be
PhysicsCurrent ElectricityJIPMERJIPMER 2011
Options:
  • A $1 \times 10^2 \mathrm{~m} / \mathrm{s}$
  • B $1.56 \times 10^{-2} \mathrm{~m} / \mathrm{s}$
  • C $1.56 \times 10^{-3} \mathrm{~m} / \mathrm{s}$
  • D $1 \times 10^{-2} \mathrm{~m} / \mathrm{s}$
Solution:
2248 Upvotes Verified Answer
The correct answer is: $1.56 \times 10^{-2} \mathrm{~m} / \mathrm{s}$
Drift velocity, $v_d=\frac{1}{n e A}$
$\Rightarrow v_d=\frac{5}{\left(5 \times 10^{26}\right) \times\left(1.6 \times 10^{-19}\right) \times\left(4 \times 10^{-6}\right)}$
$=\frac{1}{64}=1.56 \times 10^{-2} \mathrm{~ms}^{-1}$

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