At room temperature, copper has free electron density of $8.4 \times 10^{28} m^{- 3}$ . The electron drift velocity in a copper conductor of cross-sectional area of $10^{- 6} m^{2}$ and carrying a current of 5.4 A, will be

4 m s^{- 1}

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0.4 m s^{- 1}

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4 c m s^{- 1}

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0.4 m m s^{- 1}

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Solution

The correct option is D $0.4 m m s^{- 1}$
Drift velocity is the average uniform velocity attained by free electrons inside metal by the application of an electric field which is responsible for current through it.
Drift velocity in a conductor is given as:
$\Rightarrow v_{d} = \frac{i}{n e A}$
$= \frac{5.4}{8.4 \times 10^{28} \times 1.6 \times 10^{- 19} \times 10^{- 6}} m / s$

$= 4 \times 10^{- 4} m / s$

$= 0.4 m m / s$

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At room temperature, copper has free electron density of 8.4×1028m−3. The electron drift velocity in a copper conductor of cross-sectional area of 10−6m2 and carrying a current of 5.4 A, will be

At room temperature, copper has free electron density of $8.4 \times 10^{28} m^{- 3}$ . The electron drift velocity in a copper conductor of cross-sectional area of $10^{- 6} m^{2}$ and carrying a current of 5.4 A, will be