A copper wire of diameter 1.02 mm carries a current of 1.7 amp. Find the drift velocity (vd) of electrons in the wire.
Given n, number density of electrons in copper = 8.5 x 1028 /m3.
Answer & explanation
Correct answer: option 4
I = 1.7 A
$ J =\text{ current density }= \frac{I}{\pi r^2} = \frac{1.7}{3.14\times (0.51\times 10^{-3})^2} = nv_d e = 8.5\times 10^{28} \times v_d \times 1.6\times 10^{-19}$
$ v_d = 1.5 mm/sec$