The semiconductor is a homogeneous, p-type material in thermal equilibrium for t ≤ 0. The excess minority carrier lifetime is 10^-6 ns. At t = 0, an external source is turned on which produces excess carriers uniformly at rate of g'=1020 cm^-3s^-1. At t = 2*10^-6 s , the external source is turned off.

(a) Derive the expression for the excess-electron concentration as a function of time for 0 ≤ t ≤[infinity].

(b) Determine the value of excess electron concentration at (i) t = 0, (ii) t = 2*10^-6 s , (iii) t = 3*10^-6 s and (iv) t = [infinity].

(c) Plot the excess electron concentration as a function of time.

Two flowing streams of argon gas are adiabatically mixed to form a single flow/stream. one stream is 1.5 kg/s at 400 kpa and 200 c while the second stream is 2kg/s at 500 kpa and 100 ? . it is stated that the exit state of the mixed single flow of argon gas is 150 c and 300 kpa. assuming there is no work output or input during the mixing process, does this process violate either the first or the second law or both? explain and state all your assumptions.

Aloaded platform of total mass 500 kg is supported by a dashpot and by a set of springs of effective stiffness 72 kn/m. it is observed that when the platform is depressed through a distance x = 12.5 cm below its equilibrium position and then released without any initial velocity; it reaches its equilibrium position in the shortest possible time without overshoot. find the position and velocity of the loaded platform 0.10 sec. after its release. if a further load of 400 kg is added to the platform, find, i) the frequency of damped vibrations, and i) the amplitude of vibration after 2 complete oscillations, given that the initial amplitude is 15 cm.

If a particle moves along a path such that r : (3 sin t) m and ? : 2t rad, where t is in seconds. what is the particle's acceleration in m/s in 4 seconds? a)- 16.43 b)- 16.29 c)- 15.21 d)- 13.79