Asi sample with 1016 cm-3 donors is optically excited such that 1019 cm-3 electron/hole pairs are generated per second uniformly in the sample. the light causes the sample temperature to rise to 450 k. find the quasi-fermi levels upon shining the light on the sample. electron and hole lifetimes are both 10 μs. dp = 12 cm2/s, dn = 36 cm2/s, ni = 1014 cm-3 at 450 k.

The y form of iron is known as: a) ferrite b) cementite c) perlite d) austenite

Asingle-geared blanking press has a stroke of 200 mm and a rated capacity of 320 kn. a cam driven ram is assumed to be capable of delivering the full press load at constant force during the last 15 percent of a constant-velocity stroke. the camshaft has an average speed of 90 rev/min and is geared to the flywheel shaft at a 6: 1 ratio. the total work done is to include an allowance of 16 percent for friction a) estimate the maximum energy fluctuation b) find the rim weight for an effective diameter of 1.2 m and a coefficient of speed fluctuation of 0.10

Different types of steels contain different elements that alter the characteristics of the steel. for each of the following elements, explain what the element does when alloyed with steel.