1. 20.3 Wave Interference and Energy
Date, Section, Pages, etc.
Mr. Richter

2. Agenda Warm Up Collect Labs Review HW Introduction to Interference
Notes:
The Superposition Principle
Waves and Energy

3. Objectives: We Will Be Able To…
Describe the superposition principle with constructive and destructive interference.
Explain which properties affect wave energy and why.

4. Warm-Up: Can two waves be in the same place at the same time?
If yes, what do you think happens there?
If not, why not?

5. The Superposition Principle

6. The Superposition Principle
Waves are not physical things. They are energy.
This means the more than one wave can exist in the same place at the same time.
Think about sound: can you hear more than one thing at once?
Of course!

7. The Superposition Principle
When waves collide, their vibrations combine.
The superposition principle states that the total vibration at any point is the sum of the vibrations of each individual wave.

8. The Superposition Principle: Constructive Interference
Constructive interference occurs when two wave pulses combine to make a larger amplitude.
Example: if the number of guitars playing the same note is doubled, the amplitude is increased (it gets louder!)

9. The Superposition Principle: Destructive Interference
Destructive interference occurs when two wave pulses combine to make a smaller amplitude.
Example: noise-cancelling head phones.

10. Waves and Energy

11. Waves and Energy Reminder: the main idea about waves –
Waves transfer energy from place to place without transferring matter.
There are two factors that affect the energy of a wave:
frequency – how often the energy arrives
amplitude – how much energy arrives each time

12. Waves and Energy: Frequency
The greater the frequency of a wave, the more energy it carries.
Wave energy is proportional to frequency.
Example: trying to whip a rope more often.

13. Waves and Energy: Amplitude
The greater the amplitude of a wave, the more energy it carries.
Wave energy is proportional to amplitude.
Example: turning up the volume.

14. Wrap-Up: Did we meet our objectives?
Describe the superposition principle with constructive and destructive interference.
Explain which properties affect wave energy and why.

15. Homework
p. 447 #1, 2, 4, 5