A ruby crystal rod operates as an amplifier for the radiation at λ! = 694.3 nm that coincides with the central wavelength of the rubyâs atomic transition. The quantum efficiency of the transition is close to 100 %, the spontaneous emission lifetime is t!" = 4.3 ms, and the transition cross section at the central wavelength is ð(λ!) = 2.5 x 10!!" cm!.
a) Assuming a homogeneously broadened Lorentzian transition lineshape, calculate the transition bandwidth Îv (FWHM).

An air-conditioning system consists of a heating section and an evaporative cooler. air enters the heating section at 10°c and 70 percent relative humidity at a rate of 30m^3/min, and it leaves the evaporative cooler at 20°c and 60 percent relatively humidity. if the air conditioning system operates at a total pressure of 98 kpa, determine (a) the temperature and relative humidity of the air when it leaves the heating section, (b) the rate of heat transfer in the heating section, and (c) the rate of water added to air in the evaporative cooler