Three Switches & Lights

There are two big rooms in the Golkonda fort —one is located in the North-East side of the fort, another in the South-West corner. It takes about two minutes at a typical walking speed to reach the other room.

There are three light switches in the North-East room and the connecting light bulbs are in the South-West room. Each switch connects to one light in the South-West room. You are currently in the North-East room and you can neither hear the sound from South-West room nor see any light.

You can go from North-East room to South-West room only once, you can not re-enter the North-East room. Now, tell us, how do you find out the corresponding light for each switch (Do NOT assume that the bulbs are in the same order).

Answer to the Puzzle

Switch on any switch and wait for about 10 minutes to let the bulb heat up. Switch it off and switch on another and go to South-West room quickly. Check the two switched-off lights. The bulb whichever is hot corresponds to the switch which was on for 10 minutes. The cold bulb corresponds to the switch that you never touched. The glowing bulb corresponds to the switch, which is currently on.

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