Final answer:
The reflection of a wave from a barrier changes the wave by reversing its direction while keeping the frequency, amplitude, and speed constant. Damping, a separate effect, can affect the amplitude as the wave propagates.
Step-by-step explanation:
The reflection of a wave from a barrier changes the wave primarily by changing its direction but not its wavelength. When a wave is reflected, it doesn't undergo changes in frequency or amplitude due to reflection alone. Instead, the wave retains its original frequency and amplitude, though the direction in which the wave is traveling is reversed, relative to the barrier. The speed of the wave doesn't change upon reflection when it remains in the same medium.
The relationship between frequency and wavelength is such that they are inversely proportional to each other in a given medium. So if the reflection does not change the medium, the wavelength will not change as the frequency remains constant. It's also important to understand that damping affects the amplitude of the wave as it propagates, but this is a separate effect from reflection.