doppler's effect,,?

Question

whats doppler's effect??
what does the round type diagram related to doppler's effect mean??
i m really blank,,
plss explain me,,

Answer 1

The Doppler effect is the change in frequency and wavelength of a wave that is perceived by an observer moving relative to the source of the waves. For waves, such as sound waves, that propagate in a wave medium, the velocity of the observer and of the source are reckoned relative to the medium in which the waves are transmitted. The total Doppler effect may therefore result from either motion of the source or motion of the observer. Each of these effects is analyzed separately. For waves which do not require a medium, such as light or gravity in special relativity only the relative difference in velocity between the observer and the source needs to be considered.


For waves that travel through a medium (sound, ultrasound, etc...) the relationship between observed frequency f'and emitted frequency f is given by:


where
is the speed of waves in the medium (in air at T degrees Celsius, this is 332 + 0.59T m/s)
is the velocity of the source (the thing emitting the sound)
For waves that travel at the speed of light, such as radio waves, the relationship between observed frequency f'and emitted frequency is given by:

Change in frequency Observed frequency


where
is the transmitted frequency
is the velocity of the transmitter relative to the receiver in meters/second: positive when moving towards one another, negative when moving away
is the speed of light in a vacuum m/s
is the wavelength of the light

Because the detected frequency increases for objects moving toward the observer, the object's velocity must be subtracted when motion is moving toward the observer. (This is because the source's velocity is in the denominator.) Conversely, detected frequency decreases when the object moves away, and so the object's velocity is added when the motion is away.

Applications

A stationary microphone records moving police sirens at different pitches depending on their relative direction.
[edit] Everyday
The siren on a passing emergency vehicle will start out higher than its stationary pitch, slide down as it passes, and continue lower than its stationary pitch as it recedes from the observer. Astronomer John Dobson explained the effect thus:

"The reason the siren slides is because it doesn't hit you."
In other words, if the siren approached the observer directly, the pitch would remain constant (as vs, r is only the radial component) until the vehicle hit him, and then immediately jump to a new lower pitch. Because the vehicle passes by the observer, the radial velocity does not remain constant, but instead varies as a function of the angle between his line of sight and the siren's velocity:


where vs is the velocity of the object (source of waves) with respect to the medium, and θ is the angle between the object's forward velocity and the line of sight from the object to the observer.

Answer 2

The Doppler effect is related to the spreading or compressing of wave forms.
It is applicable to sound or electro-magnetic waves.
If you take a wave source, either light or sound,If the source is moved toward a point the point experiences a compression of the wave making it higher pitched.
If the emitter is moved away from the receiver the waves are spread apart,lowering the pitch.
A case in point.
An approaching siren. As it nears you the sound has a certain pitch when it passes the pitch changes very noticeable this is the spreading of the waves which decreases the pitch.
I hope this helps.

Answer 3

The Doppler Effect has to do with sound waves and moving objects. Imagine yourself standing next to a racetrack with the cars zipping by. As the cars come towards you, the pitch of the sound of their engines will be different than when they are going away from you. This is because when the cars are approaching the sound waves (which travel faster than the car and reach you sooner than the vehicle does) are actually being compressed. The circle diagram I think you might be referring to represents how the waves are being squashed by a moving object. http://www.btinternet.com/~j.doyle/SR/Sr6/sr6.htm has another diagram that might help you understand the process better.

Answer 4

I will make it simpler.
1.Suppose a motor cycle circles around you always at a constant distance away from you.the sound emanating from the vehicle will reach you in a uniform tone( assuming there is no cross wind).Sound of successive strokes of the engine will reach your ear at the same time interval they emanate.
2.Now you are standing by the edge of the road.The same motor cycle comes from a distance and passes very close to you.While the sound of a stroke approaches you the motor cycle also approaches you at a lesser speed.Instead of successive strokes coming from the same distance in the earlier case,,now they come from nearer and nearer spots.As a result, the interval between successive strokes.gets reduced and the sound that reaches you is compressed..When the motor cycle passes you then it moves away from you the interval between strokes becomes longer as it reaches your ears.Now the sound waves get elongated.
You will hear a rising compressed sound as the bike approaches you and a drawn out diminishing sound as it leaves you.
It is Doppler's effect.
Now an interesting situation.If the bike approaches at the same speed of sound, sounds of successive strokes will superimpose on the next and you will hear one loud single stroke only.when it is nearest to you.
Hope it helps you,thank you.

Answer 5

Doppler Effect means when there is relative motion between two bodies if on of them is producing sound there is compression & rarefaction air between these relative moving bodies will affected so this leads different wave length of sound waves i.e. when they spreading apart air between is more stretched so compression & rerifaction of air between will spread out with little resistance between them so leads to increase in wave length

Now for light which is transverse wave so we have crests & dips here. Imagine if your moving away from other object then in a single crest distance you will move out (lesser than speed of light) so with increasing distance between two bodies you have same number of waves so it means that wave count is same but distance has increased & speed of light is constant so wave length has increased opposite for moving towards

Answer 6

The sound of a motorcycle passing you on the highway, High pitched sound as it approaches you as the sound waves are compressed in their forwards projection, and low pitched as it goes away from you, as then the sound waves get elongated, as it travels away from you

Normal Pitch as it is beside you for the briefest of moments.

Picture yourself in a motorboat on a lake traveling into the waves, you hit them faster then they are spaced, (Wave compression) travel with them and then they take a longer time between waves. (Wave elongation)

The waves themselves are neither elongated nor compressed it is a relativity that makes it work out that way, the fact that you are not moving and the source of the sound (wave) is