Estimate the average drift speed of the conduction electrons in a copper wire of cross-sectional area $2.5\times10^{-7}\,\text{m}^2$ carrying a current of $2.7\,\text{A}$. Take the conduction-electron density as $9\times10^{28}\,\text{m}^{-3}$.

$v_d\approx 7.5\times10^{-4}\,\text{m s}^{-1}$.

CBSE Class 12 · 2014 · Delhi · Current ElectricityShort Answer

Estimate the average drift speed of the conduction electrons in a copper wire of cross-sectional area

2.5 \times 1 0^{- 7} m^{2}

carrying a current of

2.7 A

. Take the conduction-electron density as

9 \times 1 0^{28} m^{- 3}

Answer: $v_{d} \approx 7.5 \times 1 0^{- 4} m s^{- 1}$ .

I = n e A v_{d} \Rightarrow v_{d} = \frac{I}{n e A}

v_{d} = \frac{2.7}{9 \times 1 0 ^{28} \times 1.6 \times 1 0 ^{- 19} \times 2.5 \times 1 0 ^{- 7}} = 7.5 \times 1 0^{- 4} m s^{- 1} .

CBSE Class 12 Board · 2014 · Delhi · Subjective