question_answer 23)

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) wavelength (ii) frequency (iii) speed of propagation. (b) If the pulse rate is 1 after every 20 s, i.e. the whistle is blown for a split second after every 20 second), is the frequency of the note produced by the whistle equal to 1/20 = 0-05  

Answer:

  (a) A short pip by a whistle has neither a definite wavelength nor a definite frequency. However, its speed of propagation is fixed, being equal to speed of sound in air. (b) No, frequency of the note produced by whistle is not 1/20 = 0.05 Hz. Rather 0.05 Hz is the frequency of repetition of the short pip of the whistle.