There are two rooms in a house. In the first room there are three switches (S1, S2, S3) and in the second room there are three bulbs (B1, B2, B3). But you do not know which switch is connected to which bulb. Initially all the bulbs are off. In each room, you are allowed to enter only once. How would you determine which switch is connected to which bulb ?
17-Ans- Enter the first room, switch S1 for 5 minutes, switch it off, then switch S2 and go to the second room.
In the second room, you will see only one bulb glowing-- that is the bulb having connection with S2.
One of the other two bulbs should be hot as it was switched on for 5 minutes-- that is the bulb having connection with S1.
The other, switched off and cold bulb has connection to S3.