sTEm–at-Work Puzzle #57: Special North Pole Addition

Well, of course you might have guessed! Rudolf was playing pawball last week and bumped his
nose. Now it is bruised and will not glow. Naturally Santa should not have allowed him to play but who is going to tell Rudolf he can't play in any reindeer games? (Not Me!! J).

Anyway, the biomedical technician elf (of course there is one) went into Santa's North Pole Workshop maker space (yep best one in the world) to design and then fabricated a nose glove that fits perfectly over Rudolf's sort of swollen nose. It uses a low frequency red LED and an API that lets Santa turn on the LED using his phone. The Tech knows the relationship between wave length and frequency.  This elf also knows that Wave Number is inversely proportional to the wavelength.

From the 4 possibilities show in the graph, which LED did the Tech select for Rudolf’s nose glove? 

Submit your answers below the blog post, or at