Arsenic is diffused into a thick slice of silicon with no previous arsenic in it at 1100°C. If the surface concentration of the arsenic is 5.0 x 1018 atoms/cm3 and its concentration at 1.2 m below the silicon surface is 1.5 x 1016 atoms/cm3 , how long must the diffusion time be? (D = 3.0 x 10-14 cm2 /s for As diffusing in Si at 1100°C.)

When at a point two solid phase changes to one solid phase on cooling then it is known as a) eutectoid point b) eutectic point c) peritectic point d) peritectoid point

Afull journal bearing has a journal diameter of 27 mm, with a unilateral tolerance of -0.028 mm. the bushing bore has a diameter of 27.028 mm and a unilateral tolerance of 0.04 mm. the l/d ratio is 0.5. the load is 1.3 kn and the journal runs at 1200 rev/min. if the average viscosity is 50 mpa-s, find the minimum film thickness, the power loss, and the side flow for the minimum clearance assembly.

Which from the following instrument is commonly used to detect the high pitch butzing sound in bearings? [clo4] a)-digital ultrasonic meter b)-infrared camera c)-spectroscopic d)-vibrometer