Interference of Waves o What happens when two

Interference of Waves

o What happens when two waves meet? o Okay, how did these two waves meet? o Did they meet on e. Harmony? ? o Ha, Ha o Now I am serious… o Does the wave get bigger? o Does it get smaller?

o Observe and see while I demonstrate with the wave machine.

Let’s Discuss: o What did you observe? o Two crests going in the opposite direction will _________ when they meet. o A crest and a trough moving in the opposite direction will ______ when they meet. o What happens after they meet? o What did you see? ? ?

Interference o When two or more waves meet, a new wave is made o This is known as interference

Principle of Superposition o This principle states at any point, the amplitude of the two interfering waves is the sum of the amplitudes of the individual waves o Constructive interference: two or more waves create a larger amplitude o Destructive interference: two or more waves create a smaller amplitude

Look at the diagram below: What would the resultant wave look like? ? ?

Technology Using Interference Waves o Noise cancelling headphones use the concept of destructive interference. The electronics inside the headphones generate a wave that is out of phase with sound waves in the exterior environment. o This out of phase wave is played inside the headset o Using destructive interference the outside noise is cancelled, allowing the listener to play music at lower volumes.

Your Turn… o You will be getting a handout. o Please complete. o Once you have finished the first handout ( both sides), you will be getting another handout or lets say a “package”. o The second handout or ‘package’ is also to be completed. o Enjoy