When two waves enter the same space at the same time they can interfere in a such a way to cause a larger effect called constructive interference. They can also interfere in such a way to create a smaller effect called destructive interference. Light behaves like a wave and displays these light and dark inference patterns when setup in a clever way.
Interference is all about the Path Length Difference!
Watch the pre-lecture videos and read through the OpenStax text before doing the pre-lecture homework or attending class.
When two waves enter the same region of space at the same time they interfere in a way that obeys the Superposition of Waves. This addition of waves creates places where the peaks line up and the resultant wave is larger, which would manifest as a bright spot for light waves. There are also regions where the peak from one wave is lined up with the trough from the other and the resultant is wave cancelation, where their amplitudes add to zero and there would be a dark spot. These constructive and destructive areas are seperated by an entire gradient of partially constructive and partially destructive. The resulting interference pattern is one of the defining features of a wave.
Now, take a look at the pre-lecture reading and videos below.
