Problem - 4651
$\textbf{Three Switches}$
There are three switches in the control room. Two of them are disconnected and the other one is connected to a light in another room. Upon leaving the control room, you will not be permitted to return again. How can you determine which switch is connected to the light?
$\textbf{Solution}$
This problem can be solved in a similar way to # 4633. Turn on the first switch and leave it on for a while before turning it off. Then switch the second switch on and immediate proceed to check the light in the other room.
- If the light is on, then the second switch is the live switch.
- If the light is off, but the bulb is warm, then the first switch is live.
- If the light is off and the bulb is cold, then the third switch is live.