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  2. Doppler effect - Wikipedia

    en.wikipedia.org/wiki/Doppler_effect

    Fast moving satellites can have a Doppler shift of dozens of kilohertz relative to a ground station. The speed, thus magnitude of Doppler effect, changes due to earth curvature. Dynamic Doppler compensation, where the frequency of a signal is changed progressively during transmission, is used so the satellite receives a constant frequency ...

  3. Redshift - Wikipedia

    en.wikipedia.org/wiki/Redshift

    This is true for all electromagnetic waves and is explained by the Doppler effect. Consequently, this type of redshift is called the Doppler redshift. If the source moves away from the observer with velocity v, which is much less than the speed of light (v ≪ c), the redshift is given by

  4. Time dilation - Wikipedia

    en.wikipedia.org/wiki/Time_dilation

    When unspecified, "time dilation" usually refers to the effect due to velocity. After compensating for varying signal delays resulting from the changing distance between an observer and a moving clock (i.e. Doppler effect), the observer will measure the moving clock as ticking more slowly than a clock at rest in the observer's own reference frame.

  5. Negative frequency - Wikipedia

    en.wikipedia.org/wiki/Negative_frequency

    A negative frequency causes the sin function (violet) to lead the cos (red) by 1/4 cycle. The ambiguity is resolved when the cosine and sine operators can be observed simultaneously, because cos( ωt + θ ) leads sin( ωt + θ ) by 1 ⁄ 4 cycle (i.e. π ⁄ 2 radians) when ω > 0 , and lags by 1 ⁄ 4 cycle when ω < 0 .

  6. How does Doppler radar work? Is it accurate? Here’s what to ...

    www.aol.com/news/does-doppler-radar-accurate...

    Tune into any TV weather report and you’ll hear the words “Doppler radar.” What is it?

  7. Relativistic Doppler effect - Wikipedia

    en.wikipedia.org/wiki/Relativistic_Doppler_effect

    The relativistic Doppler effect is the change in frequency, wavelength and amplitude [1] of light, caused by the relative motion of the source and the observer (as in the classical Doppler effect, first proposed by Christian Doppler in 1842 [2]), when taking into account effects described by the special theory of relativity.

  8. Why you have COVID symptoms and a negative test: You ... - AOL

    www.aol.com/finance/why-covid-symptoms-negative...

    Your test may have given you a false negative, which are far more common than false positives, experts say. Or you may be performing the test wrong—or at the wrong time.

  9. Spectral line shape - Wikipedia

    en.wikipedia.org/wiki/Spectral_line_shape

    As the excited state decays exponentially in time this effect produces a line with Lorentzian shape in terms of frequency (or wavenumber). Doppler broadening. This is caused by the fact that the velocity of atoms or molecules relative to the observer follows a Maxwell distribution, so the effect is dependent on temperature. If this were the ...