When two identical waves meet, their amplitudes can combine or interfere with each other in different ways, depending on the phase relationship between them. The resulting amplitude at any given point is determined by the principle of superposition, which states that the displacement of a medium at a given point is the algebraic sum of the displacements caused by each individual wave.
Constructive Interference: When two identical waves meet in phase (their crests and troughs align), they undergo constructive interference. In this case, the amplitudes of the waves add up, resulting in an increased combined amplitude. The resulting wave will have a larger amplitude than the individual waves.
Destructive Interference: When two identical waves meet out of phase (their crests and troughs are misaligned), they undergo destructive interference. In this case, the amplitudes of the waves subtract from each other, resulting in a decreased combined amplitude. The resulting wave will have a smaller amplitude than the individual waves, and in extreme cases, it may even cancel out completely, resulting in no wave at all (called complete destructive interference).
Partial Interference: In some cases, when two waves meet, they may have different amplitudes or phases. The resulting wave will be a combination of the two waves, and the amplitudes will partially add or partially subtract depending on the specific phase relationship.
It's important to note that interference effects depend on various factors, including the wavelength, frequency, and direction of propagation of the waves. Interference can create complex patterns, such as standing waves or interference fringes, depending on the specific conditions and setup of the waves.