Does the Doppler Effect Double the Color Shift of a Moving Light Source?

AI Thread Summary
The discussion centers on whether the Doppler effect doubles the color shift of light from a moving source towards a colored object. The consensus leans towards the idea that the Doppler equation should be applied twice, with the second application based on the result of the first. Observations indicate that when a light source, like a car's headlights, shines on a colored object, the reflected light retains its color intensity despite the Doppler shift. The only observable effect is the relativistic Doppler shift due to the movement towards the object. This highlights the distinction between Doppler shifts in light and those used in police radar, which operate under different principles.
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I am having a friendly argument with a friend.
If a light source was moving towards a colored object at high speeds in a completely dark area, would the color shift due to the Doppler effect be doubled?

Possible theories are no (which we agree is wrong)
Yes (which may be right)
Or simply that the Doppler equation is applied twice, the second time on the result of the first equation. (Most probbable).

Thanks.
 
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691175002 said:
I am having a friendly argument with a friend.
If a light source was moving towards a colored object at high speeds in a completely dark area, would the color shift due to the Doppler effect be doubled?

Possible theories are no (which we agree is wrong)

... that's one hellava argument against democracy if I ever heard one.

Yes (which may be right)
Or simply that the Doppler equation is applied twice, the second time on the result of the first equation. (Most probbable).

Thanks.
 
Sorry, I misworded the question, The point of observation is supposed to be from the light source. (such as a car with headlights).
 
If you shine white headbeam light at a red object, the returning light contains mostly red wavelengths, because those are the wavelengths reflected. The Doppler shift in the incident light will still leave about as much intensity in the red. Thus the light reflected back toward you will be the same as if you had been at rest. The only Doppler you will observe will be the relativistic Doppler shift for your movement toward the red object.
The Doppler shift for police radar is different, because they use a relatively pure frequency, so you can't use this in court.
 
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