Abeam of electrons (with unspecified energy) is partially transmitted through a thin ti foil a) from a reliable source, find the mass density (at room temp.) and molar mass of this element. calculate the density of atoms n (in atoms/cm3, or just cm) d. b) for a foil of thickness t-72 nm , the transmitted electron beam has 43% of the incident-beam intensity. determine the mean free path length л (in nm) for scattering in in (at this energy). c) determine the total atomic scattering cross section o, for an atom at this energy. use appropriate units