Wave Behavior and the Doppler Effect

Wave Behavior and Doppler Effect

Earth and Space

Today's Agenda

• Quizizz on Wave Behavior

• Source and Observer Simulation

Review of waves

A wave is a disturbance that moves through matter or space. Waves carry energy from one place to another. 

Remember from our wave machine demonstration, the wave was created by Ms. Z flicking or hitting the machine. 

Properties of Waves

Waves have two properties: 

Frequency: the number of waves that pass a fixed point in a set amount of time. 

Wavelength: the distance between two wave crests or troughs.

Wave Behavior

BRAINSTORM: When you think of “wave behavior” what comes to mind? 

We’ll start with some scenarios of wave behavior here on Earth to help us make sense of wave behavior.

The first scenario is related to sound waves, which behave very similarly to light waves.

Open Ended

What is wave behavior?

Wave Behavior

Listen to the sound of a siren from the video. 

What do you notice about the sound of the ambulance as it moves past you?

Open Ended

What do you notice about the sound of the ambulance as it moves past you?

Wave Behavior Vocabulary

When we talk about waves and how they are interpreted, it is important to consider two things:

Source - the location in which light/sound waves are being emitted from.

Observer - The object receiving sound/light waves from the source

Siren Example

In the example of an ambulance driving by, the ambulance is the source of the sound waves. We are the observer.

Source and Observer - Waves Simulation

Today, we are going to use a simulation to observe waves, their behavior, and the relationship between source and observer.

Open Ended

What happens to sound waves when they travel from their source to an observer?

Open Ended

Imagine now that the blue dot is the ambulance or a police car that is passing at a high speed next to you (you are the receiver). Using what you have learned so far about the frequency of sound waves, what do you think explains the way you are hearing the sound from the siren? Make sure to explain this in terms of frequency of sound waves.

Open Ended

How frequent is a sound wave produced by the source?

Is the frequency of waves emitted by the source constant, or does it change as the source moves?

In other words, does the sound get faster, slower, or it is constant as the source moves along the screen?