[bonanova]

You've heard this one before.

There's a light bulb in the attic connected to one of 3 switches on the wall downstairs.

You can do anything you want with the switches, make one trip to the attic and determine which switch controls the bulb.

It's impossible to choose among three options with only 1 bit [on/off] of information, so you add another bit [warm/cold] to the mix:

1. turn switch 1 on, turn switch 2 on, leave switch 3 off.
   
2. Wait five minutes and turn switch 2 off.
   
3. Go to the attic.
   
4. Bulb on - it's switch 1.
   
5. Bulb off and warm - it's switch 2
   
6. Bulb off and cold - it's switch 3
   

Cute solution. That's the old problem. Here's the twist: the bulb is out of reach.

You can't feel it, and you don't have infrared telemetry.

So you can't distinguish off and warm from off and cold.

Can you still determine which switch controls the bulb?

[bonanova]

I think this wouldn't violate the conditions:

Turn one switch on. Go into the attic. Unscrew one of the unlit bulbs. Go back downstairs, open up the panel with the switches and check impedance in the wire. Or turn switch on and check for the current. But not with your fingers! You can buy a special screw driver with a little bulb on it for couple bucks. This way you can save the bulb too. And it is only one trip upstairs.

There's only one bulb.

[Guest]

Um, thinking outside the box here, you just turn on a light switch and you can either

See what the other two switches turn on (you usually can

)

or

See into the attic, so whichever turns the light on

or

If you can't see it that well, wait until nighttime

Edited October 22, 2008 by zeepuzzlemaster

[Prime]

There's only one bulb.

Same difference. Flip one switch on. Check resistance on the other two. Take a brick and walk upstairs. If the bulb is off, throw a brick at it. Walk downstairs and check the resistance on those two switches one more time.

Nothing beats the moth solution, though.

[Guest]

You've heard this one before.

There's a light bulb in the attic connected to one of 3 switches on the wall downstairs.

You can do anything you want with the switches, make one trip to the attic and determine which switch controls the bulb.

It's impossible to choose among three options with only 1 bit [on/off] of information, so you add another bit [warm/cold] to the mix:

1. turn switch 1 on, turn switch 2 on, leave switch 3 off.
   
2. Wait five minutes and turn switch 2 off.
   
3. Go to the attic.
   
4. Bulb on - it's switch 1.
   
5. Bulb off and warm - it's switch 2
   
6. Bulb off and cold - it's switch 3
   

Cute solution. That's the old problem. Here's the twist: the bulb is out of reach.

You can't feel it, and you don't have infrared telemetry.

So you can't distinguish off and warm from off and cold.

Can you still determine which switch controls the bulb?

if it is on it is 1st;if off nothing can be said

[andromeda]

I was thinking

Turn switch 1 on, leave it like that for couple of days. Turn it of and turn switch 2 on. Go to the attic and the light bulb that won't have any spiderweb around it is the one that was on for couple of days so it belongs to switch number 1, the one you just switched on will be 2 and it'll be covered in spiderweb, cause those little monsters use the opportunity right away. And the one that's off and covered in spiderweb is number 3.

Edited November 1, 2008 by andromeda

[bonanova]

I was thinking

Turn switch 1 on, leave it like that for couple of days. Turn it of and turn switch 2 on. Go to the attic and the light bulb that won't have any spiderweb around it is the one that was on for couple of days so it belongs to switch number 1, the one you just switched on will be 2 and it'll be covered in spiderweb, cause those little monsters use the opportunity right away. And the one that's off and covered in spiderweb is number 3.

OK. I'll buy that....

[andromeda]

OK. I'll buy that....

Thanks for answering my post...

I thought that the reason you are not responding to my post is because you were testing this option on your attic yourself!

[bonanova]

Weird-looking puzzle person found electrocuted in attic.

Broken glass and spider webs assumed responsible.

[Guest]

turn switch one on see if the light is on go downstairs turn switch one off and 2 on go downstairs and repeat for third switch and figure out which one

[andromeda]

You've heard this one before.

There's a light bulb in the attic connected to one of 3 switches on the wall downstairs.

You can do anything you want with the switches, make one trip to the attic and determine which switch controls the bulb.

It's impossible to choose among three options with only 1 bit [on/off] of information, so you add another bit [warm/cold] to the mix:

1. turn switch 1 on, turn switch 2 on, leave switch 3 off.
   
2. Wait five minutes and turn switch 2 off.
   
3. Go to the attic.
   
4. Bulb on - it's switch 1.
   
5. Bulb off and warm - it's switch 2
   
6. Bulb off and cold - it's switch 3
   

Cute solution. That's the old problem. Here's the twist: the bulb is out of reach.

You can't feel it, and you don't have infrared telemetry.

So you can't distinguish off and warm from off and cold.

Can you still determine which switch controls the bulb?

turn switch one on see if the light is on go downstairs turn switch one off and 2 on go downstairs and repeat for third switch and figure out which one

The only two things that are different from the ORIGINAL is that you can't reach the bulbs and the light bulbs are on the attic!

Edited November 2, 2008 by andromeda