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3 switches 1 light puzzle

+4 votes
asked in Manual Testing Interview Question by duke Expert (5,813 points)


There are 3 switches  and one bulb , the bulb is in the closed room and switches are out side of the room now you have to identify the correct switch of the bulb. you have only once chance to go inside the room.


1 Answer

0 votes
answered by amit_pammu Expert (5,030 points)
edited by amit_pammu
step 1 : Put On the first switch and wait for 2min , then off the switch

step 2 : Put On the second one and go to the room .

conclusion : if the correct switch was the first one , the bulb got heated , if its second one , it means bulb is lighting in the room , else it would be the third one,
commented by Mel allen
The answer  assumes two factors.
1. The bulb type is not specified. Some types of bulbs do not get hot.
2. The answer assumes that the bulb is within reach. It does not work if the bulb is covered by a light diffuser or in a high (unaccessible) ceiling.
The question is incorrect as it does not specify all the parameters to get the "answer."
commented by Bhartesh (2,730 points)
These bulbs are the simple Lightbulb, which can be getting hot after some time of lighting.

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