A silicon sample is doped with phosphorus at 1.17 parts per 1.00*10^6. Phosphorus acts as an electron donor, providing one free electron per atom. The density of silicon is 2.33 g/cm^3 and it's atomic mass is 28.09 g/mol.
a) Calculate the number of free (conduction) electrons per unit volume of the doped silicon in conduction electrons per cm^3
b) Compare the result from part a with the number of conduction electrons per unit volume of copper wire, assuming that each copper atom produces one free conduction electron. The density of copper is 8.96 g/cm^3, and it's atomic mass is 63.54 g/mol.