Acopper wire has a circular cross section with a radius of 1.25 mm. if the wire carries a current of 3.70 a, find the drift speed in mm/s of the electrons in this wire. (note: the density of charge carriers (electrons) in a copper wire is n = 8.46 × 1028 electrons/m3)

0.0557 mm / s

Explanation:

r = 1.25 mm = 1.25 x 10^-3 m, i = 3.7 A, n = 8.46 x 10^28 per cubic metre,

e = 1.6 x 10^-19 C

Let vd be the drift velocity

use the formula for the current in terms of drift velocity

i = n e A vd

3.7 = 8.46 x 10^28 x 1.6 x 10^-19 x 3.14 x 1.25 x 1.25 x 10^-6 x vd

vd = 5.57 x 10^-5 m/s

vd = 0.0557 mm / s

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scientific laws are the result of testing theories and proving them to be facts.