A sound wave with a frequency of 15 kHz emerges through a circular opening that has a diameter of 0.20 m.

Concepts:

(i) The diffraction angle for a wave emerging through a circular opening is given by sin u 5 1.22 l/D, where l is the wavelength of the sound and D is the diameter of the opening. What is meant by the diffraction angle?

(ii) How is the wavelength related to the frequency of the sound?

(iii) Is the wavelength of the sound in air greater than, smaller than, or equal to the wavelength in water? Why?

(iv) Is the diffraction angle of the sound in air greater than, smaller than, or equal to the diffraction angle in water? Explain. Calculations: Find the diffraction angle u when the sound travels (a) in air and (b) in water.