Find the drift velocity of electrons in a metal conductor having density of conduction electrons $9 × 10^{28} m^{-3}$ of cross sectional area $2× 10^{-7} m^2$ carrying 2 A current:

0.7 mm/s

The correct answer is Option (1) → 0.7 mm/s

The driff velocity of electrons in a metal conductor ($v_d$)

$v_d=\frac{I}{nAe}$

where,

I, Current = 2 A

n, Number density of conduction $e=9×10^{28}m^{-3}$

A, cross-sectional area = $2×10^{-7}m^2$

On substituting the values,

$v_d=\frac{2}{9×10^{28}×2×10^{-7}×1.6}$

$=0.000694m/s$

$≃0.7m/s$