Today, we calculated the thickness of a sheet of paper based on the measurements made in yesterday’s activity. It was very challenging to accurately count the number of fringes on the glass slides. In addition, I don’t have a micrometer to check the thickness of the paper. So, the only confirmation was that the calculated thickness was reasonable. I’ll need to acquire a micrometer for next year.
Some students are drawn to the thin-film interference equations in our textbook like a moth to a flame. I’m trying to convince them that they don’t need any equations to solve these types of problems. If they consider if the reflected waves as phase shifted and then determine if constructive or destructive interference is needed, they can reason through all of these problems.