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
> 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. Here's another one with fewer assumptions, but a bit more work.
Assuming there is a one-to-one correspondence between switches and lights, and assuming the wiring is in good shape, then another solution is to take a screwdriver and disassemble two switches, connect a D cell where one switch used to be and a transistor radio battery where the other used to be, walk calmly downstairs and measure the voltage across each socket after taking out the light bulb.
_________________
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