Author |
Topic: Light Bulbs And Switches Variation (Read 10948 times) |
|
alien2
Uberpuzzler
Gender: 
Posts: 6986
|
 |
Light Bulbs And Switches Variation
« on: Sep 28th, 2020, 6:45am » |
 Quote  Modify
|
You are in a room with four light switches, each of which controls one of four incandescent 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?
Clue/Spoiler: I decided to edit the post and delete the clue. You have to solve the riddle on your own.
|
| « Last Edit: Sep 30th, 2020, 11:16am by alien2 » |
 IP Logged |
|
|
|
rmsgrey
Uberpuzzler
    
Gender:
Posts: 2873
|
|
Re: Light Bulbs And Switches Variation
« Reply #1 on: Sep 28th, 2020, 9:16am » |
Quote Modify
|
Seriously unsubtle hint that completely gives the solution away: You have two properties you can easily control (given time to work with): whether the bulb is currently lit or not, and whether or not it's warm from having been lit for the last, say, hour
Solution: Name the switches A, B, C and D. Turn A and B on. Wait an hour. Turn B off and C on. Enter the bulb room immediately, and feel the four bulbs. The hot, bright one is A; hot, dark one is B; cold, bright one, C; cold, dark one, D
|
|
IP Logged |
|
|
|
alien2
Uberpuzzler
Gender:
Posts: 6986
|
|
Re: Light Bulbs And Switches Variation
« Reply #2 on: Sep 28th, 2020, 9:24am » |
Quote Modify
|
You win. Of course.
on Sep 28th, 2020, 9:16am, rmsgrey wrote:| Seriously unsubtle hint that completely gives the solution away (...) |
|
Not necessarily, since this is a variant of a well-known riddle. But, I agree with you, and so I removed the clue. In my defense, I am an Aquarius. In other words, to err is human.
|
| « Last Edit: Sep 28th, 2020, 9:28am by alien2 » |
IP Logged |
|
|
|
rmsgrey
Uberpuzzler
Gender:
Posts: 2873
|
|
Re: Light Bulbs And Switches Variation
« Reply #3 on: Sep 29th, 2020, 9:28am » |
Quote Modify
|
There's also a question about what "standard light bulb" means nowadays - based on a quick Google, the phrase seems to be mostly used to refer to the size, shape and fitting, not to how it actually works - so a "standard light bulb" could be a halogen bulb, or an LED bulb, but probably isn't a traditional incandescent filament bulb - which means the solution is under threat, since it relies on secondary characteristics that aren't universal to modern bulbs.
|
|
IP Logged |
|
|
|
alien2
Uberpuzzler
Gender:
Posts: 6986
|
|
Re: Light Bulbs And Switches Variation
« Reply #4 on: Sep 30th, 2020, 6:59am » |
Quote Modify
|
As long as the bulbs do not gradually brighten to help wake you up more naturally (and can also gently dim at night to help you drift off to sleep a little more peacefully) I suppose it is okay. But, you're right. And so I corrected the riddle accordingly.
|
| « Last Edit: Sep 30th, 2020, 11:19am by alien2 » |
IP Logged |
|
|
|
Grimbal
wu::riddles Moderator
Uberpuzzler
Gender:
Posts: 7527
|
|
Re: Light Bulbs And Switches Variation
« Reply #5 on: Oct 8th, 2020, 12:27am » |
Quote Modify
|
BTW how long are your tentacles?
OK. Here is an ootb solution.
- You switch on 2 lights and go to the room. Say lights A and B are on.
- You remove the bulbs A and C and connect the wires (or wrap the bulbs with aluminium paper and put them back).
- You return to the control room and switch on the different switches, see for which switch the fuse blows. Replace the fuse as necessary.
(putting the aluminium paper should already have made the fuse blow)
- The switches that were on are A and B.
- The switches that make the fuse blow are A and C.
This is enough to identify which switch goes with what lamp.
Oh, and put a sign on the switches: "Do not operate, fire hazard!".
|
| « Last Edit: Oct 8th, 2020, 12:30am by Grimbal » |
IP Logged |
|
|
|
|
RIDDLES SITE
WRITE MATH!
Home 
Help 
Search 
Members 
Login 
Register
Reply
Notify of replies
Send Topic
Print