When two waves interfere, the resulting amplitude can indeed change due to constructive or destructive interference. However, the frequency and wavelength of the individual waves remain unaltered during interference. This is a fundamental property of waves known as the principle of superposition.
The principle of superposition states that when two or more waves overlap or intersect, the resulting wave at any given point is determined by the algebraic sum of the displacements produced by each individual wave. This summing of wave amplitudes can lead to constructive interference, where the amplitudes reinforce each other, or destructive interference, where the amplitudes cancel each other out.
Here's why the frequency and wavelength remain constant during interference:
Frequency: The frequency of a wave is determined by the source that produces it and remains constant throughout its propagation. When two waves interfere, they maintain their respective frequencies. Constructive interference increases the amplitude, but it does not change the frequency of the individual waves. Similarly, destructive interference decreases the amplitude, but it does not alter the frequency either.
Wavelength: The wavelength of a wave is the spatial distance between successive crests or troughs of the wave. It is also determined by the source and remains constant during interference. When two waves interfere, the wavelengths of the individual waves do not change. The interference pattern is determined by the phase relationship between the waves, which affects how they combine and create regions of constructive or destructive interference.
In essence, interference affects the amplitude of waves but not their frequency or wavelength. The frequency of a wave corresponds to the number of complete cycles it undergoes per unit of time, while the wavelength represents the physical distance of one complete cycle. These characteristics are intrinsic to the source of the waves and are independent of interference effects.