Solutions to WU’s puzzles and riddles : Light Bulb and Switches (medium)

3 Bulbs

I am trying to find all the solutions and put them together at a single place, So feel free to add comments and if you have a solution please do post. Cheers … 🙂

Here is the puzzles link : http://www.wuriddles.com/

Question : You are in a room with three light switches, each of which controls one of three light bulbs in the next room. Your task is to determine which switch controls which bulb. All lights are initially off, and you can’t see into one room from the other. You are allowed only one chance to enter the room with the light bulbs. How can you determine which light switch goes with which light bulb?

My Solution : For this solution, we need to use some thermal laws ….. 😛 , sounds funny, but there is no other way. Here we are given 3 bulbs and 3 switches and we can go inside only once. Lets say the Bulbs are named B1,B2,B3 and the corresponding switches are S1,S2,S3. Now what we do is, we switch on the switch S1 and wait for half an hour. After that , we switch on S2 and go inside. After going inside, the bulb which is glowing is B2 obviously.  And now hold the other 2 bulbs. And you can observe that one of the bulb will be hot because it was switched on and kept for half an hour. So that bulb is none other than our S1 and the remaining bulb is S3 … 🙂


5 Responses to “Solutions to WU’s puzzles and riddles : Light Bulb and Switches (medium)”

  1. 2 nomina grace
    October 11, 2012 at 12:07 am

    May I borrow that lightbulb picture?

  2. April 7, 2013 at 2:49 am

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  3. September 26, 2016 at 3:19 pm




  4. September 30, 2016 at 12:17 am




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