(a) State the law of reflection of sound.
(b) With the help of a clearly labelled sketch, explain why the angle of incidence of a sound wave on a smooth rigid surface is equal to the angle of reflection.
(c) A student rotates a smooth reflecting board through 10∘ clockwise about an axis perpendicular to the plane of incidence while keeping the incident sound ray fixed. The student claims that the angle between the incident and the reflected rays decreases by 20∘. Do you agree with the claim? Give a reasoned justification based on the law you stated in part (a).