Atransistor is made by doping silicon (si) wafer with different phosphorus (p) dopants. it was given that si wafer contains no p to begin with. the diffusion coefficient of pin si is 6.5 x 10^-13 cm^2/s at temperature of 1100 c. assume the source provides a surface concentration of 10^20 atoms/cm^3 and diffusion time is one hour. compute the depth at which the concentration of p will be 10^18 atoms/cm^3 by using fick's second law.

Give heat transfer applications for the following, (i) gas turbines (propulsion) ) gas turbines (power generation). (iii) steam turbines. (iv) combined heat and power (chp). (v) automotive engines

The proportional limit is always greater than the yield strength for a material. a)-trune b)- false

Ashielded metal arc-welding operation is accomplished in a work cell by a fitter and a welder. the fitter takes 5.5 min to load components into the welding fixture at the beginning of the work cycle, and 1.5 min to unload the completed weldment at the end of the cycle. the total ength of the weld seams 1200 mm, and the travel speed used by the welder averages 300 mm/min. every 600 mm of seam length, the welding stick must be changed, which takes 0.8 min. while the fitter is working, the welder is idle (resting): and while the welder is working the fitter is idle. (a) determine the average arc-on time as a fraction of the work cycle time. (b) how much improvement in arc-on time would result if the welder used flux-cored arc welding (manually operated), given that the spool of weld wire must be changed every 10 weldments, and it takes the welder 5.0 min to accomplish the change? (c) what are the production rates for these two cases (weldments completed per hour)? attach your work and solutions.