A copper wire of radius 1 ~mm contains 10^ 22 free electrons per cubic metre. The drift velocity for free electrons when 10 ~A current flows through the wire will be (Given, charge on electron =1.6 × 10^ -19 C )

Correct answer: D. (6.25)/(π) × 10^3 ~m ~s^ -1 V_d=(i)/(n e A) aligned & V_d= 10 10^ 22 × 1.6 × 10^ -19 × π(10^ -3 )^2 & V_d= 10 1.6 π × 10^ -3 & =(6.25)/(π) × 10^3 ~m / s aligned

NEET 2023

Exam: NEET
Year: 2023
Subject: Physics
Chapter: Current Electricity

NEET 2023 · Physics · Current Electricity

A copper wire of radius 1 ~mm contains 10^ 22 free electrons per...

A copper wire of radius

1 \mathrm{~mm}

contains

10^{22}

free electrons per cubic metre. The drift velocity for free electrons when

10 \mathrm{~A}

current flows through the wire will be (Given, charge on electron

=1.6 \times 10^{-19} \mathrm{C}

)

Options

A $\frac{6.25}{\pi} \mathrm{m} \mathrm{s}^{-1}$
B $\frac{6.25 \times 10^5}{\pi} \mathrm{m} \mathrm{s}^{-1}$
C $\frac{6.25 \times 10^4}{\pi} \mathrm{m} \mathrm{s}^{-1}$
D $\frac{6.25}{\pi} \times 10^3 \mathrm{~m} \mathrm{~s}^{-1}$

Correct answer

D. $\frac{6.25}{\pi} \times 10^3 \mathrm{~m} \mathrm{~s}^{-1}$

Step-by-step solution

V_d=\frac{i}{n e A}

\begin{aligned} & V_d=\frac{10}{10^{22} \times 1.6 \times 10^{-19} \times \pi\left(10^{-3}\right)^2} \\ & V_d=\frac{10}{1.6 \pi \times 10^{-3}} \\ & =\frac{6.25}{\pi} \times 10^3 \mathrm{~m} / \mathrm{s}\end{aligned}

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