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My physics teacher asked me this :Outside a room there are three light switches. One of switch is connected to a light bulb inside the room.

Each of the three switches can be either 'ON' or 'OFF'.

You are allowed to set each switch the way you want it and then enter the room(note: you can enter the room only once)

Your task is to then determine which switch controls the bulb ??


Set the first switch on for about 10 minutes, and then switch on the second switch and then enter the room.
Three cases are possible:
1.Bulb is on => second switch is the answer
2.Bulb is off and on touching bulb , you will find bulb to be warm
=>1st switch is the answer
3.Bulb is off and on touching second bulb , you will find bulb to be normal (not warm)
=>3rd bulb is the answer
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if it was useful please mark as best
Switch on the second switch..keep it on for some time and then switch off the second switch.Now switch on the third switch and enter the room.
If the bulb is on-
3rd switch operates the bulb.
If the bulb is off but is at normal room temperature-
1st switch operates the bulb
If the bulb is off but is hot-
2nd switch operates the bulb.

Hope i helped u:)
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