A 063mmdiameter copper wire carries a tiny current of 28 mu

A 0.63-mm-diameter copper wire carries a tiny current of 2.8 mu A. The molar mass of copper is 63.5 g/mole and its density is 8900 kg/m^3. N_A = 6.02 times 10^23. Estimate the electron drift velocity. Assume one free electron per atom Express your answer to two significant figures and include the appropriate units

Solution

a ) I = n e A v_d = n e (1 / 4pi D²) v_d

2.8 * 10^-6 = (6.02 * 10²³) (1.6 * 10^-19) (1 / 4pi (0.63 * 10^-3)²) v_d

v_d = 1.44 * 10^-16 m/s