Calculate the average drift speed v d of electronstraveling through a copper wir

Question

Calculate the average drift speed vd of electronstraveling through a copper wire with a cross-sectional areaof 1.10 mm2 when carrying acurrent of 1.10 A (valuessimilar to those for the electric wire to your study lamp). It isknown that about one electron per atom of copper contributes to thecurrent. The atomic weight of copper is 63.54 grams/mol, and itsdensity is 8.92 g/cm3. First, calculate the number ofcurrent carrying electrons per unit volume, n.
what is thedrift speed?
what is thedrift speed?

Explanation / Answer

Current I = 1.1 A

Area A = 1.1 * 10 ^ -6 m^2

Current density J = I / A

                           = 10 ^ 6 A / m^ 2

Atomic weight M = 63.54 g / mol

Density D = 8.92 g / cm ^ 3

Mass of cm^3 is  m = 8.92 g

Mass of m ^ 3 volume is m ‘ = 8.92 * 10 ^ 6g

No.of moles in m ^ 3 is  n = m ‘ /M

                                            = 140384 mol

No.of charge carriers in m^ 3 volume is N = 140384 * 6.023* 10 ^ 23

                                                                    =845.532 * 10 ^ 26 / m ^ 3

SO, drift speed v = J / nq

Where q = 1.6 * 10 ^ -19 C

So, v = 7.391 * 10 ^ -5 m / s   

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