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## Turn on the light

This puzzle was probably not a major challenge to many of you.

Here is my solution.

After thinking of fitting dimmer switch to one of the switches, or a circuit that would make one of the lights blink, or even thoughts of techniques to timestamp the order in which switches were turned and therefore allowing determination of the one to one correspondence, I had a small but no less precious eureka moment when the hot water of the shower hit my skin.

### Solution

Label the switches 1,2,3 however you wish.

Turn on switch 1 and wait 30 minutes then turn on switch 2.

Immediately go into the room with the bulbs.

The bulb that is not lit is connected to switch 3.

Feel the air over the bulbs. The hottest bulb is connected to switch 1 and the remaining bulb is connected to switch 2.

Alternative solutions are welcome.

Post script:
In the event you think that the bulbs will reach steady state temperature too quickly and that feeling the lit bulb will not discriminate then you can repeat above and just before entering room turn off switch 1. Then the cold unlit bulb is connected to switch 3, the warm unlit bulb is connected to switch 1 and the lit bulb is connected to switch 2.