The current in a 2.20 mm X 2.20 mm square aluminum wire is 1.00 AWhat are (a) the current density and (b) the electron drift speed?
(a) To find current density (J), the equation is just J I / A, where I the current and A is the area of the surface In this case I 1.00 Amp and the cross sectional area A isn't given, but you can find it using 2.20mm x 2.20mm Don't forget though to convert mm into m before dividing the current by area, to get m^2(1000mm 1m - 2.20mm 0.0022m) A 0.0022m(0.0022m) 4.84E-6 Thus, you have J (1.00A) / (4.84E-6) 206611.57 A/m^2 (b) The electron drift speed can be found using this equation: v J/nq, where v is the drift speed you are trying to find, J is the density you just found, q the charge of an electron, and n the number of charges carried per unit volume (the electron density)For aluminum n 6.02E28 electrons/m^3 So v 206611.57 / ((6.02E28)(1.6E-19) in m/s v 2.15E-5 m/s
