The electron concentration in silicon at T = 300 K is given by n(x) = 10^16 exp (-x/18) cm3
where x is measured in m and is limited to 0< or is equal to x < or is equal to 25 m. The electron diffusion coefficient is Dn = 25 cm2/s and the electron mobility is mun = 960 cm2/V-s. The total electron current density through the semi-conductor is constant and equal to Jn = 40 A/cm2. The electron current has both diffusion and drift current components. Determine the electric field as a function of x-bar which must exist in the semi-conductor.

Liquid flows at steady state at a rate of 2 lb/'s through a pump, which operates to raise the elevation of the liquid 100 ft from control volume inlet to exit. the liquid specific enthalpy at the inlet is 40.09 btu/lb and at the exit is 40.94 btub. the pump requires 3 btu/s of power to operate. if kinetic energy effects are negligible and gravitational acceleration is 32.174 tt/s, the heat transfer rate associated with this steady state process is most closely 1)-2,02 btu/s from the liquid to the surroundings 2)-3.98 btu/s from the surroundings to the liquid. 3)-4.96 btu/s from the surroundings to the liquid. 4)-1.04 btu/s from the liquid to the surroundings.