From: Phys-l [mailto:phys-l-bounces@phys-l.org] On Behalf Of John Denker
Sent: Wednesday, December 18, 2013 11:11 AM
To: Phys-L@Phys-L.org
Subject: [Phys-L] just for fun
> You start out in the attic. There are three switches. It is known that there are three light bulbs in the basement. The switches control the lights, but you don't know which goes with which. You get to make *one* trip to the basement to figure this out. How?
Just for fun. Assuming that there is a one-to-one correspondence between switches and lights, assuming that all lights work, and assuming that you know which way is "on" for all three switches, then one solution is to turn two lights on for a few minutes, then turn one off, and quickly run downstairs to see which light is dark but warm.
_________________
Christopher M. Gould 213-740-1101 Dept. of Physics & Astronomy
gould@usc.edu Univ. of Southern California http://physics.usc.edu/~gould/ Los Angeles, CA 90089-0484