A narrow sound pulse (for example, a short pip by a whistle) is sent across a medium. (a) Does the pulse have a definite (i) frequency, (ii) wavelength, (iii) speed of propagation? (b) If the pulse rate is 1 after every 20 s, (that is the whistle is blown for a split of second after every 20 s), is the frequency of the note produced by the whistle equal to 1/20 or 0.05 Hz?
(a) The narrow sound pulse does not have a fixed wavelength or frequency because a pulse is a part of a wave, it is not a wave in itself. However, the speed of the sound pulse remains the same, which is equal to the speed of sound in that medium.
(b) The short pip produced after every 20 sec means that 0.05 Hz is the frequency of the repetition of the pip of the whistle. It does not mean that the frequency of the whistle is 1/20 0r 0.05 Hz.