(a) in your own words, explain how donor impurities in semiconductors give rise to free electrons in numbers in excess of those generated by valence band–conduction band excitations.

(b) also, explain how acceptor impurities give rise to holes in numbers in excess of those generated by valence band–conduction band excitations.

Acompressor receives the shaft work to decrease the pressure of the fluid. a)- true b)- false

Consider a large isothermal enclosure that is maintained at a uniform temperature of 2000 k. calculate the emissive power of the radiation that emerges from a small aperture on the enclosure surface. what is the wavelength ? , below which 10% of the emission is concentrated? what is the wavelength ? 2 above which 10% of the emission is concentrated? determine the wavelength at which maximum spectral emissive power occurs. what is the irradiation incident on a small object placed inside the enclosure?

Find the minimum film thickness for a journal bearing with the data below. shaft diameter, d-50 mm, clearance ratio, cdratio? 0.001, shaft speed, n 2000 rpm; bearing length. i 200 mm; eccentricity ration, ? -0.55. ( note, cdratio-ca/d) the minimum film thickness is um