SOLUTION: Fred (who loved to lecture) explained to Bruce and Frank that the area where Frank had parked his Mustang was in an area lit only by sodium vapor street lights. And, because it was an industrial area, the lights were most likely low pressure sodium rather than high. "You see," he droned on "Low pressure sodium is very efficient but puts out almost a monochromatic spectrum - almost completely orange yellow. That's why it's used in applications where color perception doesn't matter. Of course, your car would have appeared mostly black even under the broader spectrum but less efficient high pressure sodium that has replaced much of the low pressure units. Neither low nor high pressure sodium lighting emits any energy near the blue spectrum. So, ergo, the Camaro had nothing to reflect and thus appeared black. Q.E.D."
Frank and Bruce had dozed off but still got the general idea.
ORIGINAL PUZZLE: To cut costs, Hinterland Electric has discontinued providing company cars to all but it’s most senior executives. As a result, Frank, Senior Electrical Engineer, had to drive his fully restored, baby blue ’64 Mustang to a major late afternoon outage at a substation in the seedy industrial area of Whipemhard. Not wanting to subject his prize ride to potential dents and scratches in the crowded substation parking section, Frank parked the mustang several blocks away in an area with plenty of street lights and close to a major boulevard where cops were less afraid to patrol.
The repairs took longer than expected and as darkness fell, Frank became concerned about his car. So he asked Bruce (an intern and anxious to please) to go check.
After about an hour, Bruce returned. He said “I looked everywhere around where you said it was parked and I couldn’t find it! There’s a Mustang parked on that block alright. But it’s black, not blue.”
Frank started to call the police and report his car stolen when Fred, an electrician working nearby, started laughing. “Wait, I know the problem!”, he said. After explaining to Frank and Bruce, Frank decided to call it a day and went home.
Bruce, the intern, was later reassigned to record high voltage power line noise on some of Hinterland’s most remote transmission.
Do you know why Bruce couldn’t find Frank’s car?