A doped n-type silicon sample with 10 16 electrons per cubic centimeter in the conduction band has

Question:

A doped n-type silicon sample with 10¹⁶ electrons per cubic centimeter in the conduction band has a resistivity of 5 × 10^-3 Ω · m at 300 K. Find the mean free path of the electrons. Use the effective mass of 0.2m_e for the mass of the electrons. Compare this mean free path with that of conduction electrons in copper at 300 K.