If sunlight shines straight onto a peacock feather, the feather appears bright blue when viewed from 15° on either side of the incident beam of light. the blue color is due to diffraction from parallel rods of melanin in the feather. other wavelengths in the incident light are diffracted at different angles, leaving only the blue light to be seen. the average wavelength of blue light is 470 nm. assuming this to be the first order diffraction, what is the spacing of the melanin rods in the feather?

When using two-wire cable to feed a 240-v appliance that does not require a neutral wire, you should a. mark both ends of the white wire green. b. use the cable as is. c. use only the black wire. d. mark both ends and any exposed area of the white wire black.

4r-134a enters the condenser of a residential heat pump at 800 kpa and 50°c at a rate of 0.022 kg/s and leaves at 750 kpa subcooled by 3°c. the refrigerant enters the compressor at 200 kpa superheated by 4°c determine (a) the isentropic efficiency of the compressor, (b) the rate of heat supplied to the heated room, and (c) the cop of the heat pump. also, determine (d) the cop and rate of heat supplied to the heated room if this heat pump operated on the ideal vapor-compression cycle between the pressure limits of 200 and 800 kpa. (0.757, 4.37 kw, 5.12, 6.18, 3.91 kw)

Explain what it means to view something from a frame of reference. provide an example that illustrates your explanation. (4 points)