29 A source of sound waves approaches a stationary
observer through a uniform medium. Compared
to the frequency and wavelength of the emitted
sound, the observer would detect waves with a
(1) higher frequency and shorter wavelength
(2) higher frequency and longer wavelength
(3) lower frequency and shorter wavelength
(4) lower frequency and longer wavelength
The observer detects waves which are the same frequency and wavelength as
the waves emitted ahead of the moving source and lower frequency and longer
wavelenth than the waves emitted behind the moving source.
The desired answer (1) is correct for the alternative question: Compared to
the frequency and wavelength of the sound which an identical stationary
emitter would emit, the observer detects waves with a : . . .