Drift velocity: Building codes usually limit the current carried by a 1.6-mm diameter copper wire to 15 A. Many household circuits are wired with this size wire. What is the drift velocity of the electrons in this case?. Assume one conduction electron per atom in copper. The atomic weight of copper is 63.3 g/mol and its density is 8900 kg/m³. Avogadro's number is 6.022 × 10²³ molecules/mol and e = 1.60 × 10^-19 C.

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The drift velocity is given by:$$v_d = \frac{I}{neA}$$where:* I is the current* n is the number of conduction electrons per unit volume* e is the charge of an electron* A is the cross-sectional area of the wireWe can find the number of conduction electrons per unit volume using the following formula:$$n = \frac{N_A ho}{A_r}$$where:* N_A is Avogadro's number* $ho$ is the density of the material* A_r is the atomic weight of the materialPlugging in the given values, we get:$$n = \frac{(6.022 	imes 10^{23} 	ext{ molecules/mol})(8900 	ext{ kg/m}^3)}{63.3 	ext{ g/mol}} = 8.49 	imes 10^{28} 	ext{ electrons/m}^3$$The cross-sectional area of the wire is:$$A = \pi r^2 = \pi (0.8 	imes 10^{-3} 	ext{ m})^2 = 2.01 	imes 10^{-6} 	ext{ m}^2$$Plugging in all the values, we get:$$v_d = \frac{15 	ext{ A}}{(8.49 	imes 10^{28} 	ext{ electrons/m}^3)(1.60 	imes 10^{-19} 	ext{ C})(2.01 	imes 10^{-6} 	ext{ m}^2)} = 5.51 	imes 10^{-4} 	ext{ m/s}$$

Drift Velocity: Building Codes Usually Limit the Current Carried by a 1.6-Mm