For sound waves, the
Doppler formula for frequency shift differs slightly between the two
situations: (i) source at rest; observer moving, and (ii) source
moving; observer at rest. The exact Doppler formulas for the case of
light waves in vacuum are, however, strictly identical for these
situations. Explain why this should be so. Would you expect the
formulas to be strictly identical for the two situations in case of
light travelling in a medium?
For sound waves, the Doppler formula for frequency shift differs slightly between the two situations: (i) source at rest; observer moving, and (ii) source moving; observer at rest. The exact Doppler formulas for the case of light waves in vacuum are, however, strictly identical for these situations. Explain why this should be so. Would you expect the formulas to be strictly identical for the two situations in case of light travelling in a medium?
No
Sound waves can
propagate only through a medium. The two given situations are not
scientifically identical because the motion of an observer relative
to a medium is different in the two situations. Hence, the Doppler
formulas for the two situations cannot be the same.
In case of light waves,
sound can travel in a vacuum. In a vacuum, the above two cases are
identical because the speed of light is independent of the motion of
the observer and the motion of the source. When light travels in a
medium, the above two cases are not identical because the speed of
light depends on the wavelength of the medium.
No
Sound waves can propagate only through a medium. The two given situations are not scientifically identical because the motion of an observer relative to a medium is different in the two situations. Hence, the Doppler formulas for the two situations cannot be the same.
In case of light waves, sound can travel in a vacuum. In a vacuum, the above two cases are identical because the speed of light is independent of the motion of the observer and the motion of the source. When light travels in a medium, the above two cases are not identical because the speed of light depends on the wavelength of the medium.
