The Doppler Effect

Question 1

What is the Doppler Effect?

Answer 1

The change in wavelength or frequency of a wave as the source and observer move relative to each other.

Question 2

What happens to sound waves when the source moves toward the observer?

Answer 2

Sound waves are compressed, frequency increases, and pitch sounds higher.

Question 3

What is an example of the Doppler Effect in sound when a fire engine approaches?

Answer 3

The fire engine siren sounds higher as it approaches due to compressed sound waves.

Question 4

What occurs to sound waves when the source moves away from the observer?

Answer 4

Sound waves are stretched, frequency decreases, and pitch sounds lower.

Question 5

What happens to light waves when an object moves toward the observer?

Answer 5

Light waves are blue-shifted, indicating a shorter wavelength.

Question 6

What happens to light waves when an object moves away from the observer?

Answer 6

Light waves are red-shifted, indicating a longer wavelength.

Question 7

How is the Doppler Effect used in astronomy?

Answer 7

It is used to measure the speed and direction of stars/galaxies through redshift/blue-shift.

Question 8

What does the Doppler Effect help us understand about the universe?

Answer 8

It helps us understand the expansion of the universe.