KLB BOOK 3 PG.207-211 https://www.youtube.com/watch?v=GDwRvv5NZLA www.phys.uconn.edu/~gibson/Notes/Section5_2/Sec5_2.htm https://www.khanacademy.org/...interference.../constructive-and-destructive-interference. https://www.youtube.com/watch?v=CRhsPoTOHIU