Sound waves diverge in a spherical shape or __________.

• A. Diffraction pattern
• B. Huygen's wavelet
• C. Wavefront
• D. Interference pattern

Answer: (B)

Sound propagates outward from a point source by Huygens's principle: every point on a advancing wavefront becomes a source of secondary wavelets, and the new wavefront is the envelope of those wavelets. From a point source, these secondary wavelets expand in all directions, forming spherical fronts. That’s why the divergence takes a spherical shape. So the term that best captures this mechanism is Huygens's wavelet, since it describes the tiny sources that generate and shape the spreading wavefront. The other ideas describe related phenomena but not the basic spreading mechanism: a diffraction pattern comes from interference and bending around objects, a wavefront is just the surface of constant phase itself, and an interference pattern results from superposing multiple waves rather than the outward spreading from a single point source.