Monday, April 15, 2013

Thomas Edison's Light Bulb Test

Thomas Edison, the inventor of the incandescent bulb, was an incessant inventor.   When he needed to expand his staff, he  employed an unusual technique for interviewing the engineers for positions on his staff.  Every prospective  applicant who came in for an interview was handed a light bulb.  Edison then asked the engineer to determine the exact amount of water the bulb could hold.

Edison knew very well that there were two basic ways an applicant could determine the correct answer to his question.

The first, was to apply several engineering gauges and mathematical protractors to each of the complex angles of the glass bulb. Then, using a slide ruler and applying basic logarithmic formulas, the applicant could calculate the inside surface area of the light bulb which would allow him to determine the total volume of the glass bulb. This approach would take an experienced engineering applicant approximately twenty minutes to solve the answer.

The second method an applicant could use to find the answer was to remove the brass base from the bulb and then fill the bulb with water.   Once the bulb was filled with water, its contents could easily be poured into a measuring cup or laboratory beaker mug to determine the exact amount of water it could hold.   This method generally took less than two minutes.

Nearly all the engineers who used the first method to calculate the volume of water a light bulb could hold were politely thanked for their time and sent on their way. However, the applicants who used the second method were greeted warmly by Mr. Edison who asked, "When can you start?"