at room temperature the electrical conductivity of pbte is 500 (ω-m)–1, whereas the electron and hole mobilities are 0.16 and 0.075 m2/v-s, respectively. compute the intrinsic carrier concentration for pbte at room temperature.

In this problem we are asked to compute the intrinsic carrier concentration for PbTe at room temperature. 

Since the conductivity and both electron and hole mobilities are provided in the problem statement, all we need do is

solve for n and p

Thus,

n=s/e(me+ mh)

n = 500 / (1.602 x10-19) ( 0.16 + 0.075)

= 1.33 ´ 10^22

none, its a machine