An echo from which reflector is most dependent on the angle of incidence?

An echo from which reflector is most dependent on the angle of incidence?

• A. Rayleigh Scatterer
• B. Diffuse Reflector
• C. Specular Reflector
• D. Acoustic Scatterer

Answer: (C)

The key idea is how reflection works for different kinds of surfaces. A specular reflector behaves like a mirror: the energy obeys the law of reflection, so the angle of incidence equals the angle of reflection. Because of that, the portion of energy that returns to the source (the echo) depends strongly on the exact incidence angle—tilt the surface, and the reflected energy may miss the receiver, weakening or eliminating the echo. In contrast, a Rayleigh scatterer (tiny particles) and a diffuse reflector (rough surface) scatter energy in many directions, so the received echo is less tied to the precise incidence angle. An acoustic scatterer likewise disperses energy rather than reflecting it in a single direction. So the angle-dependence of the echo is greatest for a specular reflector.

The key idea is how reflection works for different kinds of surfaces. A specular reflector behaves like a mirror: the energy obeys the law of reflection, so the angle of incidence equals the angle of reflection. Because of that, the portion of energy that returns to the source (the echo) depends strongly on the exact incidence angle—tilt the surface, and the reflected energy may miss the receiver, weakening or eliminating the echo.

In contrast, a Rayleigh scatterer (tiny particles) and a diffuse reflector (rough surface) scatter energy in many directions, so the received echo is less tied to the precise incidence angle. An acoustic scatterer likewise disperses energy rather than reflecting it in a single direction. So the angle-dependence of the echo is greatest for a specular reflector.