A wire made from copper with a cross-section of diameter 0.890 millimeter carries a current of 13.0 Amp. Determine the "areal current density"; in other words, determine how many electrons per square meter per second flow through this wire?
The density of copper is 8.92g/cm3, and its atomic mass is 64.0. Assuming each copper atom contributes one mobile electron to the metal, find the number density of free charges in the wire, in electrons/m3?
Due to thermal motion, the electrons at room temperature are randomly traveling to and fro at1.12 × 105 m/s, even without any current. Find what fraction is the current drift speed, compared to the random thermal motion?