The bandgap of gallium arsenide (GaAs) is 1.4 eV. Find the optimum wavelength of light for PV generation in a GaAs solar cell.​

Aloaded platform of total mass 500 kg is supported by a dashpot and by a set of springs of effective stiffness 72 kn/m. it is observed that when the platform is depressed through a distance x = 12.5 cm below its equilibrium position and then released without any initial velocity; it reaches its equilibrium position in the shortest possible time without overshoot. find the position and velocity of the loaded platform 0.10 sec. after its release. if a further load of 400 kg is added to the platform, find, i) the frequency of damped vibrations, and i) the amplitude of vibration after 2 complete oscillations, given that the initial amplitude is 15 cm.

An air conditioning system consist of a 5 cm diameter pipe, operating at a pressure of 200 kpa. the air initially enters the pipe at 15°c with a velocity of 20 m/s and relative humidity of 80%. if the heat supply throughout the process is 960 w, determine the relative humidity and the temperature at the outlet

Assuming compressible flow of air and that the measurements are done at flagstaff a pitot static tube that gives the difference of total and static pressure measures 0.35 m of mercury. what is the velocity of air? assume the temperature to be 300k. (submit your excel or matlab calculation sheet)