試題詳解

45. For a sound wave travelling in a cylinder along the x-direction, a snapshot of the displacement field of air molecules is shown in the following figure. At which marked position, the sound wave possesses the largest energy density? The wave equation of sound is

(A) The sound wave at A, C, and E all possess the largest energy density.
(B) Only at point A since its amplitude is the largest.
(C) Only at point C since it has the largest curvature.
(D) The sound wave at B and E possess the largest energy density.
(E) Only at point D since it has the largest slope.