Bulb and Switch Puzzle


You have a set of 3 light switches outside of a closed door. One of them controls the light inside the room. You can turn the light switches on or off as many times as you would like.You can go into the room – one time only – to see the light. You cannot see the whether the light is on or off from outside the room, nor can you change the light switches while inside the room.Based on the information above, how would you determine which of the switch controls the light inside the room?



– Turn ON  the first switch and keep it ON for 10 mins and  turn OFF.

– Turn ON the second switch. Go inside the room and check if the bulb is turned ON.

– If  its ON then correct switch is 2nd . If the bulb is hot then correct switch is 1st else answer is the 3rd switch.

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