the doppler effect

Re: the doppler effect


http://electronics.howstuffworks.com/radar1.htm

The Dopler Effect can be picked up many ways.

For one it's an effect of wave theory. A motor boat traveling in both directions with respect to the motion of the waves is one I have always liked. Easily visualized and all that Put the boat in a river rather than a lake and you can include gravitation and time in your presentation.

When Einstein realized that "light" conformed to wave theory and gravitation to accelleration he gave us a whole new way of looking at things.

Why don't you google "Wave Theories" "Red shift", and "Relativity" in order to give yourself a bit of background

okay, you're familiar with it. I'm not, please explain thanks

OK Crayon. I'll start with my favorite.

(you realize that when discussing light the frequencies of waves are perceived as color and frequency is the number of waves passing a point during a specific time interval. Wave length is the distance that the wave peaks are separated. (Usually measured in nanometers). The wave lengths have differing characteristics. Think prism. Wave length and frequency are precisely related with electromagnetic waves as long as you don't mess around with gravity. Radio waves are measured in meters. (look at your short wave radio dial)


Imagine that you are in a boat in the middle of a river. There are wind generated waves in the river. Make it easy on us, make the waves go along the same path as the river.

Let the boat drift. Count the waves as they go by. (number of waves per unit of time) ie. frequency
Anchor the boat. Count the waves as they go by.
Put up the sail, go downwind. Count the waves.
Turn around and motor upwind. Count the waves.
Stand underneath a waterfall. Count the waves again.
Go downstream from a bridge. Have somebody drop a rock into the water.(Count etc.)
Go upstream from the bridge. Have the rock dropped and count again.

This with many more possible points of observation will illustrate both the Doppler effect and some relativity theory.
The main disadvantage with this analogy is that water waves move much more slowly than light waves or even sound waves.

When you realize that most, if not all, energy transfers utilize waves to transmit sound, light, vibrations, etc. that will get you started.

The Doppler effect is the logical outcome of a difference in relative motion between the observer and the emitter.

It also shows up as a difference in the speeds of time depending on your location. But that gets pretty deep into the nature of things and we are probably not ready to go there yet

I understood everything up to "The doppler effect is"

I'm not a science person, so I think I need a bit more of an explanation and what exactly is the importance and relevance of the doppler effect?

The sudden change in pitch of a car horn as a car passes by (source motion) or in the pitch of a boom box on the sidewalk as you drive by in your car (observer motion) was first explained in 1842 by Christian Doppler. His Doppler Effect is the shift in frequency and wavelength of waves which results from a source moving with respect to the medium, a receiver moving with respect to the medium, or even a moving medium.

try a google search if all u want is general info. www.google.com

Crayon,

As an emitter of waves, be it a horn, flashlight, or star moves toward you the waves will be seen by an observer (you) to come closer together than they were when they were emitted.
Thusly----
Sound waves are higher in pitch when emitter comes at you and lower as the emitter recedes.

The water waves will be closer together (higher in pitch if they were sound waves) as you went upwind or anchored and farther apart as you drifted or blew downwind.

Sound waves;emitter approaching; are higher in pitch.(wave length shortened.)
Sound waves; emitter receding=lower
Light waves; emitter approaching; are higher in pitch (blue shifted-wave length shortened.)
Light waves; emitter receding; are lower in pitch ; red shifted (wave length longer.

The "shift " refers to the directions of the Electromagnetic Spectrum. Something else for you to Google

The "Doppler Gun" loved by state troopers and small town budget directors, simply takes these differences and electronically calibrates them into miles per hour.

This effect is very noticeable in a sailboat as a good sailboat can run nearly as fast downwind as the wind is traveling which is usually faster than the waves travel. It is very possible to run downwind at 5or6 miles per hour yet the sailboat and water will appear to be nearly perfectly calm to the passengers. Turn it around and you are thrashing and crashing and getting splashed.

Are you beginning to understand what Einstein figured out Understanding wave theory is the beginning of understanding relativity.

If you really get into it our notions of time, space, distance,speed,gravity,and matter itself are all dependent upon "wave theory". Doppler effect is just a little part of it. (unless you just got a speeding ticket)