andrewkirk said:The wave speed and frequency measured by the observer will change, with both increasing by the same proportion. The wavelength will remain the same. It has to, in order for the equation ##v=f\lambda## to hold.
With electromagnetic waves, the frequency and wavelength both change, and the wave speed remains constant at ##c##. The special theory of relativity is used to explain the difference between this treatment and that for sound waves.
That is correct.Mr Davis 97 said:However, in the case where the source is moving towards the observer, the wavelength is smaller; so would frequency change so that velocity remains the same?
For sound waves, the observed propagation velocity isn't more, if the observer is at rest relative to the medium, and only the source moves. For EM-wave there is no medium, and the observed propagation velocity is always the same.CrazyNinja said:When the source moves towards the observer, the observed frequency is more. The observed velocity is more too because of relative motion.
No it isn't. The wave propagation velocity is determined by the motion of the medium (the air, in the case of sound), not the motion of the emitter. So the velocity is the same.CrazyNinja said:The observed velocity is more too because of relative motion.
The speed in that equation is the speed of the wave relative to the medium. This does not change in Doppler effect.andrewkirk said:The wave speed and frequency measured by the observer will change, with both increasing by the same proportion. The wavelength will remain the same. It has to, in order for the equation ##v=f\lambda## to hold.
I think he means a sound source at rest to the medium.nasu said:Wavelength changes in both cases.
Yeah I meant that.A.T. said:I think he means a sound source at rest to the medium.
The Doppler effect is a phenomenon that occurs when there is a change in frequency or wavelength of a wave as it moves towards or away from an observer. This change in frequency is perceived as a change in pitch or sound for sound waves, and a change in color for light waves.
The Doppler effect does not directly affect velocity, but it is caused by a relative motion between the source of the wave and the observer. This relative motion can affect the perceived frequency and wavelength of the wave, which in turn can give us information about the velocity of the source or the observer.
The terms Doppler effect and Doppler shift are often used interchangeably, but there is a slight difference between the two. The Doppler effect refers to the actual change in frequency or wavelength of a wave, while the Doppler shift refers to the perceived change in frequency or wavelength by an observer.
The Doppler effect has many practical applications in various fields. In astronomy, it is used to determine the velocity and distance of celestial objects. In medicine, it is used in ultrasound technology to measure blood flow and detect abnormalities. In traffic control, it is used in radar guns to measure the speed of moving vehicles.
The Doppler effect can be observed with all types of waves, including sound, light, and water waves. However, the magnitude of the effect may vary depending on the speed of the source and the observer, as well as the medium through which the wave is traveling.