The Doppler effect is observed whenever the source of waves is moving with respect to an observer. The Doppler effect can be described as the effect produced by a moving source of waves in which there is an apparent upward shift in frequency for observers towards whom the source is approaching and an apparent downward shift in frequency for observers from whom the source is receding. It is important to note that the effect does not result because of an actual change in the frequency of the source. Using the example above, the bug is still producing disturbances at a rate of 2 disturbances per second; it just appears to the observer whom the bug is approaching that the disturbances are being produced at a frequency greater than 2 disturbances/second. The effect is only observed because the distance between observer B and the bug is decreasing and the distance between observer A and the bug is increasing.
The Dopplereffect can be observed for any type of wave - water wave, sound wave, light wave, etc. We are most familiar with the Dopplereffect because of our experiences with sound waves. Perhaps you recall an instance in which a police car or emergency vehicle was traveling towards you on the highway. As the car approached with its siren blasting, the pitch of the siren sound (a measure of the siren’s frequency) was high; and then suddenly after the car passed by, the pitch of the siren sound was low. That was the Dopplereffect - an apparent shift in frequency for a sound wave produced by a moving source.
Wild Flower under the Milky Way
“This flower is called Primula Denticulata and is located at 1500-3000m above sea lelvel in northern part of Yunnan, China. I had strong desire to take a macro image of these flowers and it took me an hour hour to find them. Putting the camera on the slope, focusing, composition and lightning were all very difficult but the worst thing is shortness of time to moonrise. I had to leave soon.” — Jeff Dai
Barbara Stanwyck, 1943
Mejor llamado nivel Enrique Peña Nieto.
A whole new meaning for the phrase sexual appetite.