Puzzle: 3 light switches; 3 bulbs; Which light switch controls which light bulb?

You are in a room with three switches which control three light bulbs in a room way on the other side of the building. You can go into the room with the light bulbs only once. How do you figure out which light switch goes with which light bulb? No tools allowed. Nobody can help you. No cell phones.
7 answers 7