1. Discuss how a missing atom at a lattice sidecontributes to the conductivity of asemiconductor    Â
2. Estimate the energy of a photon of X rays. (Answer:12 keV)
3. On the one hand, we say thatelectrons in atoms have discrete energies; on the other hand, wesay that there is inherent uncertainty in our ability to measureenergies. Is there a conflict here?
4. You have just calculated the number density ofp-carriers in undoped germanium, a semiconductor, at roomtemperature. Is it necessary to make a second calculation to findthe number density of free electrons?
5. Estimate the energy of a photon of visible light.(Answer: 2.4 eV)
