Friday, August 2, 2013
The Doppler Effect and long-planet
We are all familiar with the Doppler Effect, even if you do not know the term. Today, scientists have found an alternative explanation for the phenomenon when the sound or the light spinning object is scattered. This discovery could help astronomers to measure the rotation of the planet, or even improve the performance of wind turbines.
Here is what the principle of the Doppler Effect: when the object emitting the noise is moving towards its sound waves converge together and produce a higher frequency. Conversely, when the subject moves away, the sound waves are scattered. The faster the object moves, the sharper the frequency difference.
The Doppler Effect is relevant for light. For example, astronomers determine how quickly move away stars and galaxies by measuring the degree to which their light is "stretched" in the lower frequencies, the red part of the spectrum. These redshifts were used in 1920, after which it became known that most of the stars and galaxies are moving us and the universe is likely to expand.
Scientists have been researching, directing the laser on a plastic rotor spinning rapidly. They collected the scattered light to the sensor, which turned them into two types of signals: positive (clockwise rotation) and negative (counter-clockwise) signals to the orbital angular momentum. Although the rotor did not change the total orbital angular momentum of light, he translated the positive signals in the higher frequency and negative - on the contrary. Researchers have used this frequency separation to determine the speed of rotation of the rotor.
Most facilities do not exude light: they scatter and reflect light of other objects, such as a lamp or the sun. On this basis, there is an assumption that can be applied to the Doppler Effect for the scattered light. For example, an astronomer could use it to determine the rotation of the distant planets. On Earth, a laser can be directed to identify the station wind speed airflows.
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