Doppler Effect
What is the Doppler Effect
- A property in which the frequency in the wave is constant, but while observing the wave from different positions, the frequency seems to change
- When the observant is closer to the source of the waves , the observed frequency increases
- When the observant is further away, the observed frequency decreases
What is Observed Frequency?
- The frequency based on the observer's point of view
- Can change based on the actual frequency of the waves or position of the observer
Doppler Effect Applet
- When there is no velocity, the frequency stays the same
- When there is velocity and movement in a source of wave, the direction of the source of wave, the closer the wave/frequency is to each other, while the opposite side's wave/frequency is further away
- The faster the velocity, the closer the wave/frequency is to each other
- The faster the velocity, the louder the sound will be when it passes the microphone, but the softer after is passes the microphone
- The slower the velocity, the further the wave/frequency (when it is moving)
- The slower the velocity the lower the volume before and after it passes the microphone
Examples of Doppler Effect
- As the ambulance proceeds towards the observer, the observed frequency increases
- As the ambulance passes the observer, the observed frequency decreases
- The observer's position does not change, however the position of the source of waves changes
- The source of waves would be the ambulance
- The observer in this instance is the kid
- The girl who is farther away from the police car is observing a lower frequency
- The boy who is closer to the police car is observing a much higher frequency
- In this case, the police car is the source of waves
- There are two observers in this; the girl away from the source and the boy who is closer
- There is a bug in the center of a puddle.
- There is only one medium
- It's shaking its legs
- The wave is travelling in all directions from that point at the same speed
- Each observer (A and B) notice that the frequencies of the puddles are the same
- However, the bug is moving right, still at the same frequency.
- The waves originate from a position closer to B, and further from A.
- Each wave travels less towards observer B, and faster as well.