Good afternoon, dear guests and subscribers of the "Build for Myself" channel!
Our local electrician yesterday changed the wires for me from single-core aluminum to self-supporting insulated wire, going from the pole to the meter on the facade of the house. While he was working, we got to talking a little and during the conversation he asked me an interesting problem.
And, since my channel is devoted to the arrangement of the site and the construction of a house, therefore I bring to your attention this logical puzzle on a similar topic.
The condition of the problem is as follows:You enter the vestibule of a three-story building and see 3 switches. You need to determine which switch lights the first floor incandescent lamp. When going through the keys of these switches, it is not visible whether the light is on or not, since the front door between the vestibule and the first floor is closed.
Question: How to determine which of the three switches corresponds to turning on / off the lamp of the first floor, provided that you can open the door, enter and go up to the first floor to the lamp only one time?
When solving, you can use the illustration below (for clarity, I tried to depict everything very close to the condition of the problem).
The line of reasoning and the answer:
If there were two switches, the answer would be as simple as five kopecks.
But we have three switches, each of which has only two states "on" or "off", and also - we have an incandescent lamp, which can also only be in two states: either "on" or "off". And in any case, in the search for a switch, we will definitely turn on some lamp by pressing the switch button, and turn off some, but what to do with the third switch is not clear!
Obviously, we need to introduce some other lamp state ...
In the course of thinking, we understand that a lamp that has been burning for some time is heating up. Thus, we have two more states, as a result there are four of them: "burning", "not burning", "warm", "cold".
Now, we can bind our new states to the switches: for the lamp to burn, you need to turn on the switch so that the lamp does not burn - you need to turn off the switch so that the lamp is cold - do nothing, and warm - you need to turn on the switch and wait a while (conditionally 2 minutes), then turn it off.
Answer
Now it is enough for us, having entered the vestibule, press the button of any switch, wait 2 minutes, turn it off and turn on the next one.
As a result: If the lamp on the first floor turns out to be warm - this was the first switch, if the lamp is on - this is the second, if the lamp is not lit and cold - this is the remaining third switch!
Thank you for your patience and attention! I really hope you enjoyed the puzzle!
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