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

4 ms^-1

0.4 ms^-1

4 cm s^-1

0.4 mm s^-1

Solution

0.4 mm s^-1

Drift velocity in a copper conductor

v_d = $\frac{i}{n e A}$

where, i ⇒ the current

v_d ⇒ the drift velocity

e ⇒ the charge

n ⇒ the free electron density

⇒ v_d = $\frac{5.4}{8.4 \times 10^{28} \times 1.6 \times 10^{- 19} \times 10^{- 6}}$

⇒ v_d = 0.4 × 10^-3 ms^-1

⇒ v_d = 0.4 mms^-1

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