3 Switches

PureRWandB View Profile

Posers and Puzzles

11 Aug '12 20:57

PureRWandB
CCC Club Leader
Denver, CO
Joined
23 Feb '03
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11 Aug '12 20:57
Three switches outside a windowless room are connected to three light bulbs inside the room. How can you determine which switch is connected to which bulb if you are only allowed to enter the room once?
forkedknight
Defend the Universe
127.0.0.1
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12 Aug '12 15:33
Originally posted by PureRWandB
Three switches outside a windowless room are connected to three light bulbs inside the room. How can you determine which switch is connected to which bulb if you are only allowed to enter the room once?
Are they LED's?

This puzzle isn't going to make sense in 20 years 🙂
AThousandYoung
Insanity at Masada
tinyurl.com/mw7txe34
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12 Aug '12 18:46
Originally posted by forkedknight
Are they LED's?

This puzzle isn't going to make sense in 20 years 🙂
nope, incandescent bulbs
SwissGambit
Caninus Interruptus
2014.05.01
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13 Aug '12 04:24
Originally posted by PureRWandB
Three switches outside a windowless room are connected to three light bulbs inside the room. How can you determine which switch is connected to which bulb if you are only allowed to enter the room once?
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Leave the left switch on for an hour. Turn it off and turn the middle one on. Enter the room. The hot bulb is connected to the left switch, the lit bulb is connected to the middle switch, etc.
Jono3000
Joined
12 Apr '10
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731
13 Aug '12 04:35
I guess it would be possible to trace each wire with your hands by walking through the window with a hand tracing two of the wires and using the rules of elimination to figure out the other light bulb and switch.
SwissGambit
Caninus Interruptus
2014.05.01
Joined
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14 Aug '12 01:22
Originally posted by Jono3000
I guess it would be possible to trace each wire with your hands by walking through the window with a hand tracing two of the wires and using the rules of elimination to figure out the other light bulb and switch.
There is no window.
jayteedee
Joined
21 Jul '12
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15 Aug '12 02:09
Turn one switch on After a half hour turn it off and turn another on. Then go in the room. One bulb will be on, corresponding to the switch you just turned on. There will be two bulbs turned off; but one of them will be warm, corresponding to the switch you turned on for a half hour. The cold one will correspond to the switch that was never turned on.
forkedknight
Defend the Universe
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15 Aug '12 19:41
Originally posted by AThousandYoung
nope, incandescent bulbs
Now solve for LED's
SwissGambit
Caninus Interruptus
2014.05.01
Joined
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16 Aug '12 05:08
Originally posted by forkedknight
Now solve for LED's
Take a sledge hammer to the sheetrock. Trace wiring. This solves without even entering the room. 😏
mmmjv
Joined
03 Sep '12
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2516
23 Sep '12 04:40
Originally posted by forkedknight
Now solve for LED's
Same as Jayteedee's except you turn one on and wait till it burns out? then before going in turn one of the other two on. Can you tell if an LED bulb is burned out? I mean besides it doesn't give any light. If not I guess you could take some kind of meter in there or something
tomtom232
Joined
15 Jun '06
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16334
26 Sep '12 00:48
LED

Turn the left switch on and leave it for a few days.

When you come back turn the middle switch on

Enter room

Dim light belongs to the left switch

Bright one to the middle etc
iamatiger
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26 Apr '03
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26771
26 Sep '12 15:231 edit
Enter the room, replace the leds with bulbs of 3 known different resistances, noting the positions

Exit the room and take apart the switches, then use a multimeter to determine which switch is connected to which bulb.
Shallow Blue
Joined
18 Jan '07
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28 Sep '12 13:30
Originally posted by iamatiger
Enter the room, replace the leds with bulbs of 3 known different resistances, noting the positions

Exit the room and take apart the switches, then use a multimeter to determine which switch is connected to which bulb.
A proper geek's solution. I salute you, sir.

Richard
iamatiger
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26771
29 Sep '12 13:18
Find someone else to stand outside the room and turn each switch on and off in an agreed order while you watch the bulbs from inside the room.
Thequ1ck
Fast above
Slow Below
Joined
29 Sep '03
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25914
09 Oct '12 08:58
Put one switch on. Wait 5 minutes and put another switch on.

The bulb that is out will be the switch that is off, the bulb that is hot will
be the first switch you put on and the bulb that is cooler will be the last
switch put on.