In a particular semiconductor material, the effective density of states functions are given by nc nc0· (t300)32 and nv nv0· (t300)32 where nc0 and nv0 are constants independent of temperature. experimentally determined intrinsic carrier concentrations are found to be ni 1.40 102 cm3 at t 200 k and ni 7.70 1010 cm2 at t 400 k. determine the product nc0 nv0 and the bandgap energy eg. (assume eg is constant over this temperature range.)

Apump is used to circulate hot water in a home heating system. water enters the well-insulated pump operating at steady state at a rate of 0.42 gal/min. the inlet pressure and temperature are 14.7 lbf/in.2, and 180°f, respectively; at the exit the pressure is 60 lbf/in.2 the pump requires 1/15 hp of power input. water can be modeled as an incompressible substance with constant density of 60.58 lb/ft3 and constant specific heat of 1 btu/lb or. neglecting kinetic and potential energy effects, determine the temperature change, in °r, as the water flows through the pump.

During a steady flow process, the change of energy with respect to time is zero. a)- true b)- false

Water in a partially filled large tank is to be supplied to the roof top, which is 8 m above the water level in the tank, through a 2.2-cm-internal-diameter pipe by maintaining a constant air pressure of 300 kpa (gage) in the tank. if the head loss in the piping is 2 m of water, determine the discharge rate of the supply of water to the roof top in liters per second.