Doppler Effect

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Doppler Effect

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Doppler Effect
A source of waves moving to the left. The frequency is higher on the left, and lower on the right.

The apparent change in frequency and wavelength due to the motion of the source and/or the observer.

3 types of Doppler Effect:
-observer moving towards the source
-source moving towards observer
-observer and source moving
Doppler effect also occurs if source and observer are moving away from each other i.e pitch gets lower

An Example Of The Doppler Effect Found In Wild Life:

Bats are nocturnal predators and they use the Doppler effect to estimate the distance between themselves and their prey.

Red Shift

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Red Shift

Red shift is defined as an increase in the wavelength of electromagnetic radiation

waves moving away from observer - low frequency waves - longer wavelength

Redshift and blue shift

I think the Doppler Effect Applet external link was an alright attempt at helping me understand the Doppler effect but there needs to be more of an explaination to make it clear.

The police car demo gave a clear visual of how the doppler effect works but i think a few sentences needs to be added to give more of an explanation of the demo.

Blue Shift

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Blue Shift

-Blue shift is defined as a decrease in wavelength

waves moving towards observer - high frequency waves - shorter wavelength


The Doppler Effect does not occur at 90 degrees (right angle).

A Helicopter's spinning turbine frequency is heard when perpindicular to you.

External Resources

Red/Blue Shift


Police Car this link gives a good visual understaning of the doppler effect and is easy to use and is fun to play around with. however no notes are given. i give this site 2/5 stars. Spar300

This site is on topic and helpful. Definatly should be kept. jshe128

Doppler Effect DemoThis is a short and sweet explanation of the doppler effect. It simply explains the relationship between the speed of the source and the observed sound in terms of wave frequency.On topic, very clear, there are other similar resources but a little variety is fine. Keep it. It's helpfulness depends on wether you understand the doppler effect or not. Repeats what we've learned in class- perhaps best as a revision tool.Bada003 12:23, 30 May 2008 (NZST)

Basic video explanation of Doppler shift(

Doppler Effect Applet

Video on youtube about the doppler effect: