Imagine the surface of a lake on a day that is windy, many wave motions are visible. Even though it may not look like it, these waves are moving in different directions, with different wave lengths and amplitudes. When the waves meet, a new wave is formed, this is called interference. When waves meet and interfere with each other two things can happen, depending on what kind of waves are involved.
So what does interference mean?
“Interference is the process of generation a new wave when two or more waves meet.” (Nelson Physics 11 9.1)
Watch this very helpful video on how different waves interfere to produce new waves:
Constructive interference can be defined as “the process of forming a wave with a larger amplitude when two or more waves combine.”
Destructive interference can be defined as “the process of forming a wave with a smaller amplitude when two or more waves combine.”
It is important to remember that when a crest and trough interfere, they produce a smaller wave. When a crest interferences with another crest, this will produce a larger wave. To practice and understand how the interference of waves work, follow the examples in the Nelson Physics 11 textbook on page 417 below and do 9.1 question #2.