## December 9, 2008

### Light Bulb

A light bulb is hanging in the first floor of the room.
There are three switches in the ground floor room.
One of these switches belongs to that light bulb.
The light bulb is not lit and the switches are in off
state. There is only one chance to visit the room.
How can it be determined which of these switch
is connected to the light bulb.

Sai Mahesh said...

Switch on the first switch and switch it off after some time .. switch on the second switch and go to the room ...
1. If the bulb isn't lit, but the bulb is hot .. ANS is first switch

2. If the bulb is lit, ANS is second switch.

3. If neither case 1 nor 2 occurs, ANS is third switch.

Evan said...

The first floor and the ground floor may be the same floor. In this case, the switch and the bulb may be in the same room. Just turn on each switch and observe the light.

I hate it when someone butchers a well known logic problem. Please don't use ambiguous terminology when it is not needed! Thank you.

Secret SquÃ¯rrel said...

No, Evan. The first floor and ground floor are never the same. In the UK and most ex-colony countries, the first floor is always immediately above the ground floor.