When a wave reflects from a plane surface, several properties of the wave can be affected. Let's examine each of the properties you mentioned:
Wavelength: The wavelength of a wave is the distance between two consecutive peaks or troughs. When a wave reflects from a plane surface, the wavelength remains unchanged. The distance between corresponding points on the incident and reflected waves will be the same.
Frequency: The frequency of a wave is the number of complete cycles the wave completes in a given time. When a wave reflects from a plane surface, the frequency also remains unchanged. The number of cycles per second (or any other unit of time) will remain the same.
Speed: The speed of a wave is the rate at which a wave propagates through a medium. When a wave reflects from a plane surface, the speed can be affected depending on the properties of the medium. If the wave reflects from a boundary between two different media, the speed may change. However, if the wave reflects from a plane surface within the same medium, the speed remains the same.
Amplitude: The amplitude of a wave is the maximum displacement or height of a wave from its equilibrium position. When a wave reflects from a plane surface, the amplitude can be affected. The amplitude of the reflected wave may be different from the amplitude of the incident wave, depending on the nature of the reflection.
In summary, when a wave reflects from a plane surface, the wavelength and frequency remain unchanged, while the speed and amplitude can potentially be altered.