Post:
You have three switches in one room and a single light bulb in another room. You are allowed to visit the room with the light bulb only once. How do you figure out which switch controls the bulb? Write your answer in the comments before looking at other answers.
Comment:
If this were an interview question, the correct response would be "Do you have any relevant questions for me? Because have a long list of things that more deserving of my precious time than to think about this!
The official answer to this riddle is turn switch 1 on for a minute or so, switch it off then switch 2 on. if the bulb is hot but dark, its 1, if it’s lit it’s 2 and if it’s out and cold its 3.
the adult answer is why do I have only one chance to walk in the room?
this is the classic answer but it also fails pure logic because the question only implies one of them actually works, and even then, it’s only one of them. the truth is any number of them could work, or a specific combination, or a number of combinations, or it might be none. the bulb itself to could be busted. my point is not to be an uncooperative asshole but that a logic puzzle that relies on real world properties should cover its bases.
if hot they’re using out of date lighting, who the fuck uses incandescent bulbs this far into the 21st century? they have failed their interview with me.
The image does depict an incandescent filament bulb.
LED do not have a 100% efficiency, and do produce waste heat. A lot less than an incandescence one, sure, but enough for that answer to be valid.
Well, maybe you’d better wait 10min instead of one, to make sure the led lightbulb heats enough, but still…
I tested this with a 5W IKEA LED light-bulb, since I was just doom scrolling, anyway:
This means that the solution either breaks down entirely, or is unreliable, since you are not (reliably) able to tell the first two buttons apart
note the premise specifies HOT.
none of my LED bulbs get hot even after hours. they do warm up from ‘cold’ but HOT?
ymmv.
Highly arguable. Especially without specifications on the lamp. It could be a rather dim and small one. Then, you either need special equipment or supersenses.
The question is outdated as fuck too. It’s not a new riddle.
yeah silly games for bored hiring managers
The actual adult answer is questioning why the switch is in a different room and if it’s because of safety, demand for safety protocol
So I can’t go to the other room to set up a camera?
What if it’s a LED bulb?
LED bulbs do get warm, not as hot as incandescent bulbs but they do emit heat. You might have to run them longer than a minute to warm it up enough to be immediate about it.