# 20.3 Wave Interference and Energy - PowerPoint PPT Presentation

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20.3 Wave Interference and Energy. Date, Section, Pages, etc. Mr. Richter. Agenda. Warm Up Collect Labs Review HW Introduction to Interference Notes: The Superposition Principle Waves and Energy. Objectives: We Will Be Able To….

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20.3 Wave Interference and Energy

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## 20.3 Wave Interference and Energy

Date, Section, Pages, etc.

Mr. Richter

### Agenda

• Warm Up

• Collect Labs

• Review HW

• Introduction to Interference

• Notes:

• The Superposition Principle

• Waves and Energy

### Objectives: We Will Be Able To…

• Describe the superposition principle with constructive and destructive interference.

• Explain which properties affect wave energy and why.

### 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?

### 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!

### 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.

### 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!)

### The Superposition Principle: Destructive Interference

• Destructive interference occurs when two wave pulses combine to make a smaller amplitude.

### 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

### 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.

### 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.

### Wrap-Up: Did we meet our objectives?

• Describe the superposition principle with constructive and destructive interference.

• Explain which properties affect wave energy and why.

### Homework

• p. 447 #1, 2, 4, 5