[greekbird]

there are two rooms.
one room has 3 switches. the other room has a lamp
the two rooms are separated with a one way door (no gaps or keyholes in the door!)
you have to find which switch lights the lamp.

you are in the first room, you can stay there as long as you like and you can play with the switches as much as you like (this does not mean you can rip them off the wall!)

once you leave the first room to go into the next, you cannot return into the first room.

how do you work out which switch turns the lamp on?