# Drift speed of electrons, when 1.5 A of current flows in a copper wire of cross-section $5 mm^{2},$ is $\upsilon$. If the electron density in copper is $9\times 10^{28}/m^{3}$ the value of $\upsilon$ in mm/s is close to (Take charge of an electron to be = $1.6\times 10^{-19}C)$A. 0.02B. 3C. 2D. 0.2

Translatory motion of charge -

$i=nqvA$

- wherein

If there are $n$ particles per unit volume each having charge $q$ and moving with velocity $v$

I = neAVd

$V_{d} = \frac{I}{neA}$

$\frac{1.5}{9 \times 10^{28} \times1.6 \times 10^{-19} \times 5 \times 10^{-6} }$

= 0.02 x 10-3 m/s

= 0.02 mm/sec

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