A0.45 um thick sample of gaas is illuminated by a monochromatic light of photon energy 3 ev. the incident power on the sample is 15 mw/cm2. if the absorption coefficient is 50 000/cm, determine (a) the total energy absorbed by the sample per second, (b) the rate of excess thermal energy given up by the electrons to the lattice before recombination, and (c) the number of photons given off from recombination. assume perfect quantum efficiency. the outgoing radiation is of 2.35 ev.

Atransverse wave is traveling on a string stretched along the horizontal x-axis. the equation for the vertical displacement y of the string is given by y = (1.8 x 10-3)cos[π(13x - 60t)], where all quantities are in si units. what is the maximum speed of a particle of the string

Clothes dryer uses about 7 amps of current from a 240 volt line. how much power does it use?

Acommercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at -35°c by rejecting waste heat to cooling water that enters the condenser at 18°c at a rate of 0.25 kg/s and leaves at 26°c. the refrigerant enters the condenser at 1.2 mpa and 50°c. if the compressor consumes 3.3 kw of power, determine (a) the mass flow rate of the refrigerant, (b) the refrigeration load, (c) the cop, and (d) the minimum power input to the compressor for the same refrigeration load.