1. Briefly tell what is meant by the drift velocity and mobility of a free electron.
2. (a) Calculate the drift velocity of electrons in silicon at room temperature and when the magnitude of the electric field is 500 V/m.
(b) Under these circumstances, how long does it take an electron to traverse a 25-mm (1-in.) length of crystal?
3. At room temperature the electrical conduc- tivity and the electron mobility for aluminum are 3.8 X 107 (D-m)-1 and 0.0012 m2/V-s, re- spectively.
(a) Compute the number of free electrons per cubic meter for aluminum at room temperature.
(b) What is the number of free electrons per aluminum atom? Assume a density of 2.7 g/cm3.
4. (a) Calculate the number of free electrons per cubic meter for silver, assuming that there are 1.3 free electrons per silver atom. The electrical conductivity and density for Ag are 6.8 X 107 (D-m)-1 and 10.5 g/cm3, re- spectively.
(b) Now compute the electron mobility for Ag.