Interference of Waves

1. Interference of Waves

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

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

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

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

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

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

8. Technology Using Interference Waves • 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. • This out of phase wave is played inside the headset • Using destructive interference the outside noise is cancelled, allowing the listener to play music at lower volumes.

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