Please turn on javascript in your browser to play chess.
Posers and Puzzles

Posers and Puzzles

  1. 13 Nov '07 04:19
    Maybe this is an old one, but I've heard it only once, and so will take a chance that it will be new to others. There are two rooms on a corridor, and neither interior is visible from the other one. In one room are three light bulbs, all turned off. In the other room are three switches, controlling the light bulbs. You get one trip to the switch room to manipulate the switches, then you must go into the light-bulb room and declare which switch connects to which bulb. How do you do it?
  2. Standard member skeeter
    515 + 30 days
    13 Nov '07 05:06
    Originally posted by Dhango
    Maybe this is an old one, but I've heard it only once, and so will take a chance that it will be new to others. There are two rooms on a corridor, and neither interior is visible from the other one. In one room are three light bulbs, all turned off. In the other room are three switches, controlling the light bulbs. You get one trip to the switch room to m ...[text shortened]... go into the light-bulb room and declare which switch connects to which bulb. How do you do it?
    Turn one switch on, turn the second switch on briefly and then turn off. Leave the third switch in the off position. Go to the room and one bulb will be lit, one bulb will off but warm to the touch and the last bulb will also be off but cold.

    skeeter
  3. 13 Nov '07 14:37
    Originally posted by skeeter
    Turn one switch on, turn the second switch on briefly and then turn off. Leave the third switch in the off position. Go to the room and one bulb will be lit, one bulb will off but warm to the touch and the last bulb will also be off but cold.

    skeeter
    you can do it with four switches, four lamps.

    Switch two on for a while, turn one of them off, light a third one, go to the room and find:
    one hot lit, one hot off, one cold lit, one cold off.
  4. 13 Nov '07 15:19
    As low energy bulbs get more efficient, eventually this problem is going to become obsolete.
  5. Standard member wolfgang59
    Infidel
    13 Nov '07 17:05
    The new electric dark bulbs (as opposed to electric light bulbs) will also effect this problem.

    When switched on the room goes dark. Great invention!
  6. Standard member smw6869
    Granny
    13 Nov '07 18:19
    Originally posted by wolfgang59
    The new electric dark bulbs (as opposed to electric light bulbs) will also effect this problem.

    When switched on the room goes dark. Great invention!
    I have managed to accomplish this task using regular light bulbs. While doing some "Home Cooking" (electrical work".....actually i had installed three 4way switches in my living room. I can get the ceiling light to go on, but most of the time i run between 3 different switches,in the dark, until i get the right combinations of switches to work.

    Granny.
  7. Subscriber sonhouse
    Fast and Curious
    13 Nov '07 23:31
    Originally posted by mtthw
    As low energy bulbs get more efficient, eventually this problem is going to become obsolete.
    But as we are able to run faster and faster maybe one day we can get there before the last rays of light from the most recently on bulb will still be visible.......
  8. 18 Nov '07 00:13
    I knew I was asking the right group of people--thanks to all! I especially like the four-switch option, which I had never considered before. But yes, with the increasing use of low-energy bulbs, this will probably be a nonsensical riddle in a few years... Thanks again.
  9. 20 Nov '07 19:03
    Originally posted by serigado
    one hot lit, one hot off, one cold lit, one cold off.
    How can a light bulb be lit and cold? They always seem hot to me just about as soon as I switch them on. If there's any period of time when a newly-lit bulb is not hot, surely it is too brief a time for me to get across the corridor to check the bulbs!