Which statement correctly describes the behavior of waves at a boundary when they return after hitting it?

Which statement correctly describes the behavior of waves at a boundary when they return after hitting it?

• A. The bending of a wave as it passes through a boundary.
• B. The spreading of a wave around a barrier.
• C. The absorption of energy by the boundary.
• D. The returning of a wave when it hits a boundary.

Answer: (D)

When a wave hits a boundary and something about it comes back into the original medium, that returning behavior is called reflection. The wave bounces off the boundary, and with a smooth surface the angle it hits at (the angle of incidence) is equal to the angle it leaves at (the angle of reflection). This is what you see with echoes of sound off a wall or light bouncing off a mirror. Other things that can happen at a boundary include refraction, where the wave changes speed and bends as it enters a new medium; diffraction, where waves bend around edges or openings; and absorption, where energy is taken up by the boundary rather than reflected. So describing the wave as returning after hitting the boundary highlights the reflection process.

When a wave hits a boundary and something about it comes back into the original medium, that returning behavior is called reflection. The wave bounces off the boundary, and with a smooth surface the angle it hits at (the angle of incidence) is equal to the angle it leaves at (the angle of reflection). This is what you see with echoes of sound off a wall or light bouncing off a mirror.

Other things that can happen at a boundary include refraction, where the wave changes speed and bends as it enters a new medium; diffraction, where waves bend around edges or openings; and absorption, where energy is taken up by the boundary rather than reflected. So describing the wave as returning after hitting the boundary highlights the reflection process.