Mr. Z’s “Waves” Unit

Mr. Z about to catch some “Air”

Mr. Z’s “Riding One Home!”

Mrs. Z

Describe what is meant by the Doppler effect

AIM: What is the Doppler effect?

Doppler Effect, phenomenon

AIM: What is the Doppler effect?

Have you ever noticed that an ambulance or a fire truck always sounds louder (or higher) when it is traveling towards you as opposed to traveling away from you.

AIM: What is the Doppler effect?

AIM: What is the Doppler effect?

What is the frequency again?

The number of complete waves passing a given point in one second

The greater the frequency the greater the pitch of a sound

With the Doppler Effect:

The frequency seems to increase to the observer, but it really does not change

When the source of the waves is moving towards you, the waves “pile-up” creating the appearance of an increased frequency

This apparent change in frequency, is called the Doppler Effect.

AIM: What is the Doppler effect?

The Doppler effect can be observed to occur with all types of waves - most notably water waves, sound waves, and light waves.

AIM: What is the Doppler effect?

We are most familiar with the Doppler effect because of our experiences with sound waves. As a police car was traveling towards you with its siren blasting, the pitch of the siren sound (a measure of the siren's frequency) was high; and then suddenly after the car passed by, the pitch of the siren sound was low.

That was the Doppler effect - an apparent shift in frequency for a sound wave produced by a moving source.

AIM: What is the Doppler effect?

AIM: What is the Doppler effect?

The Doppler effect is of interest to astronomers who use the information about the shift in frequency of electromagnetic waves produced by moving stars in order to derive information about those stars and galaxies.

The belief that the universe is expanding is based in part upon observations of electromagnetic waves emitted by stars in distant galaxies.

Specific information about stars can be determined by application of the Doppler effect to the Electromagnetic radiation emitted by distant galaxies…

A Red Shift indicates the the star is moving away from the Earth.

A Blue Shift indicates that the star is moving towards the Earth.

Because of the Doppler effect, scientists have been able to determine that the universe is expanding.

Where else have you heard of the word “Doppler”?

AIM: What is the Doppler effect?

Who knows what that is?

AIM: What is the Doppler effect?

Doppler Radar:

If the frequency of the Doppler radar is increasing, what is that telling you?

The storm is moving towards you -- it’s a blue shift!

AIM: What is the Doppler effect?

Class Activity:

W/S Concepts 7-6

AIM: What is the Doppler Effect?

Homework:

INTERNET QUESTIONS

AIM: What is the Doppler Effect?