How to find which switch belongs to which bulb.

A room has 3 bulbs and another room has 3 corresponding switches but in a random order( not like first switch belongs to first bulb etc). Both rooms are completely isolated so that you cannot see the light when it switched on.

You are allowed ONLY ONCE to each room and you can go any room first (either Blub room or swictch room). Thats your choice.

Now tell me which switch belongs to which bulb???