Are You a Problem Solver? (continued)

Some time ago, I talked about how important problem-solving skills are to success as a customer support representative. Here is a puzzle that I once put to a group of employees from the Support department:

There are two rooms separated by a long hall way. In the first room, there are three light switches that connect to three lamps in another room. What is the minimum number of trips between the rooms needed to determine which light switch operates each lamp?

I am happy to report that an experienced support person quickly came up with the correct answer. If you think you know the answer, post it in a comment.

P.S. I heard this puzzle on the NPR radio program “Car Talk”. It's a great show with two brothers taking calls about car problems. If you are familiar with the show, you already know how entertaining they are.