Doppler Effect

The pitch of a sound wave relates to the wave's _________________.

• Amplitude

• Frequency

• Wavelength

• Period

What is the Doppler Effect?

• A change in frequency due to the relative motion of a wave source and an observer

• When a wave overlaps with another wave

• When a wave bounces off of another object

• When a wave bends due to traveling through a different medium

An ambulance is driving towards you as you stand on the sidewalk. What happens to the pitch of the siren as it comes towards you?

• It increases

• It decreases

You are driving in a car and honk the horn at a person standing in the street. As you approach the person, what happens to the pitch of the horn according to you in the car?

• It increases

• It decreases

• It stays the same because you are in the car moving with the sound.

You are standing on the side of the road when a police car races past you with its siren on. After the police car passes you, what happens to the pitch of the siren?

• It increases

• It decreases

• It turns red

A car is not moving but the horn is on. You run towards the car to investigate what's going on. As you approach the car, what happens to the frequency of the sound waves from the horn?

• They increase

• They decrease

Look at the picture. Who is experiencing a higher pitched sound?

• Observer A

• Observer B

• There's no difference

Look at the picture. Who is experiencing a lower pitched sound?

• Observer A

• Observer B

• There is no difference

What can you tell about this object's motion?

• Moving to the North (up).
• Moving to the South (down). 
• Moving to the West (left). 
• Moving to the East (right). 

What can you tell about the motion of this object?

• Moving left.
• Moving right quickly.
• Standing still. 
• Moving up slowly.