551
Op doesn't have time for interviews
(programming.dev)
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!
Here's my answer that works with any kind of lightbulb.
Flip switch 1 on, switch 2 off, and get switch 3 stuck in a halfway point which I've done on both lever switches and flat switches.
If it's on it's switch 1, if it's off it's switch 2, if it's flickering or dimmed it's switch 3 and you should probably turn it off to stop damaging the relay.
Trying to get a switch stuck half way sounds like a good way to start a fire. If the bulb is dimmed, that means not all the power is making it to the bulb, and half of it is probably going into heating up the switch contacts. It could also be arcing inside the switch, which will also destroy the contacts. I think some new building codes require "arc fault protection" on circuits for this type of reason, in addition to "ground fault protection" (GFCI) on bathroom/kitchen circuits.