ECN Forum Forums General Topics of the Trade General Discussion Area brainteaser

Ok,
There are three cieling mounted, incandecent light fixtures in the hallway of a testing laboratory. The cieling is eight feet above finished floor.
There are three single pole switches for these fixtures in a room along this hallway.
The room with the switches has a drywall cieling at eight feet and no windows.
YOU CANNOT SEE THE FIXTURES FROM THE SWITCH LOCATION.
You are allowed to enter the room one time. You can stay in there as long as you want but,once you leave the room, you can't go back in there.
You have an six foot step ladder and a voltage tester.
How do you tell which switch controls which light fixture?

Maybe I am missing something but I don't think you even need the tester. Just turn on switch 1 and leave it on for a few minutes. Turn it off. Turn on 2 and go check the lights. the light on sw 2 will be on. The one one sw 1 will be hot but off and #3 will be off and cool.

Ding Ding Ding. We have a winner

What if one of the bulbs is a dud?


You want another ticket?

Alan

good call GF.
The tester is just there to throw you off but, you wern't fooled.
You'd be surprized how many people just can't figure it out.

nicely done.