Why does frequency change in Doppler effect situations?

[cutesoqq]

I hv the following problems:

1. Using Doppler's effect, can we explain why frequency will change in two different situation?

2. What is the application of Doppler's effect?

 

[Gokul43201]

What have you done to find out (besides this post) ?

http://scienceworld.wolfram.com/physics/DopplerEffect.html

 

[Andre]

1. http://www.pinkmonkey.com/studyguides/subjects/physics/chap10/p1010201.asp

A meagre attempt to put it into words. Assume the distance between source and receptor is -say- ten wavelengths and it took T time to emit it. Now the source moves in T time (the time for the signal to travel) to -say- half the distance, the receptor has to receive not only the ten waves in between (emitted before the move) but also part of the waves that were emited during the move. Since there are now only five waves in between, the receptor must have noticed the ten waves that ware emitted in the T time plus the 5 waves that are no longer in the distance between the two.

2.
-To stop roling smilies.
-RADAR to see only objects with minimum or maximum relative speed
-RADAR to measure the realitive speed of targets. (Police, meteorolgy)
-airborne RADAR for ground mapping, enhancing the resolution (DBS)
-Astronomy: the "red shift" is doppler effect
-Medical ultrasound- or pregnacy detectors, imaging the internal organs on their movements.

and a lot more I guess

 

[cutesoqq]

thx>> Andre^^

 

[JohnDubYa]

Go to www.merlot.org and type Doppler in the search engine. Fu Kwun Hwang's and Angel Franco Garcia's java applets demonstrate the effect very convincingly. It will be obvious by examining the applets running why the frequency shifts.